3.1

15 Nervous System Diseases and Disorders

OUTLINE

• ▪ Anatomy and Physiology

  • The Central Nervous System

  • The Peripheral Nervous System

• ▪ Common Signs and Symptoms

• ▪ Diagnostic Tests

• ▪ Common Diseases of the Nervous System

  • Infectious Diseases

  • Vascular Disorders

  • Functional Disorders

  • Dementias

  • Sleep Disorders

  • Tumors

• ▪ Trauma

  • Concussions and Contusions

  • Skull Fractures

  • Epidural and Subdural Hematomas

  • Spinal Cord Injury: Quadriplegia and Paraplegia

• ▪ Rare Disesses

  • Amyotrophic Lateral Sclerosis

  • Guillain-Barré Syndrome

  • Huntington's Disease

  • Multiple Sclerosis

• ▪ Effects of Aging on the System

• ▪ Summary

• ▪ Review Questions

• ▪ Case Studies

• ▪ Bibliography

KEY TERMS

Amnesia (p. 347)

Aura (p. 340)

Carotid endarterectomy (p. 338)

Cauterization (p. 350)

Cephalalgia (p. 339)

Chorea (p. 353)

Convulsion (p. 340)

Decompress (p. 351)

Dysphagia (p. 337)

Dysphasia (p. 337)

Epidural (p. 349)

Grand mal (p. 341)

Hemiparesis (p. 337)

Hydrophobia (p. 335)

Hypothermia (p. 351)

Intractable (p. 339)

Nuchal rigidity (p. 333)

Paraplegia (p. 351)

Paresthesia (p. 353)

Petit mal (p. 341)

Quadriplegia (p. 351)

Seizure (p. 340)

Spinal stenosis (p. 339)

Status epilepticus (p. 341)

Subdural (p. 349)

LEARNING OBJECTIVES

Upon completion of the chapter, the learner should be able to:

• 1. Define the terminology common to the nervous system and the disorders of the system.

• 2. Discuss the basic anatomy and physiology of the nervous system.

• 3. Identify the important signs and symptoms associated with common nervous system disorders.

• 4. Describe the common diagnostics used to determine the type and cause of nervous system disorders.

• 5. Identify common disorders of the nervous system.

• 6. Describe the typical course and management of the common nervous system disorders.

• 7. Describe the effects of aging on the nervous system and the common disorders associated with aging of the system.

OVERVIEW

T he nervous system is a complex network that provides communication from the brain to the rest of the body and from the body back to the brain. It facilitates the individual's ability to reason, interact with other individuals, understand complex ideas, and respond both intellectually and physically. Disorders of the system can affect any or all other normal functioning in the individual. Because brain and spinal cord injury often causes irreversible damage, the individual with a nervous system disorder can become a victim of severe, permanent, neurologic deficits.

Consider This …

The brain stops growing at approximately age 18.

ANATOMY AND PHYSIOLOGY

The nervous system is composed of the brain, spinal cord, and nerves (Figure 15-1). It is divided into the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS includes the brain and the spinal cord. The PNS includes the autonomic nervous system (ANS), the cranial nerves, and the spinal nerves. The CNS communicates with organs and other body systems through the PNS.

The Central Nervous System

The brain is a complex structure located within the protective covering of the skull. It is divided into the cerebrum, cerebellum, and brain stem. The cerebrum is divided into two hemispheres that can be further subdivided into lobes. Each of these lobes has a specialized function (Figure 15-2). The basal ganglia, called the gray matter, are located deep in the hemispheres. Another part of the cerebrum is called the diencephalon. This is where the hypothalamus and thalamus are located. They are active in controlling the body's sleep-wake pattern and are involved in the actions of the hypophysis (pituitary) gland. (See Chapter 14, “Endocrine System Diseases and Disorders,” for more information.)

   The cerebellum, important in coordination and fine motor movements, is located in the lower back part of the brain.

FIGURE 15-1 The nervous system.

FIGURE 15-2 The cerebral lobes and their specialized functions.

   The brain stem makes up the last part of the brain. It is subdivided into the midbrain, pons, and medulla; contains some nerves; and is responsible for transmitting impulses that control respiration, swallowing, wakefulness, and other activities.

Consider This …

The brain holds five times as much information as the Encyclopedia Britannica, or the equivalent of 1,000 computer terabytes.

   The spinal cord is a continuous structure running through the vertebral column from the medulla to the tailbone. The spinal cord is composed of both white and gray matter. It has ascending and descending pathways that transmit impulses. Sensory impulses (pain, temperature, and touch) travel from the spinal cord to the brain. Motor impulses (for movement of muscles) travel from the brain to the spinal cord.

Consider This …

Pain travels through the body at a speed of 350 feet per second.

TABLE 15-1 The Cranial Nerves

   The meninges are membranes that cover the brain and spinal cord. The meninges are divided into three layers: the dura mater (outer cover), the arachnoid (middle layer), and the pia mater (inner layer). They provide both protection and support for the system.

The Peripheral Nervous System

The ANS controls the functions of the body's organs and innervates smooth muscle and cardiac muscle. It is divided into the parasympathetic and sympathetic systems. The parasympathetic system controls the changes in the body needed to relax and restore function, such as returning blood pressure to normal after it has increased in response to some need. The sympathetic system controls the changes in the body needed to respond to stressors, such as increasing the heart rate or blood pressure—the fight-or-flight response.

   Twelve pairs of cranial nerves control sensation and movement in the area of the head and neck (Table 15-1). Thirty-one pairs of spinal nerves are divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Each spinal nerve innervates designated areas, called dermatomes, of the skin (Figure 15-3). Each of the spinal nerves sends sensory impulses from the body organs and surfaces to the spinal cord for transmission to the brain and returns motor impulses from the brain to the spinal cord and then to the muscles.

FIGURE 15-3 Spinal nerves and dermatomes.

Consider This …

Twenty-five percent of the brain is used to control the eyes.

COMMON SIGNS AND SYMPTOMS

Common signs and symptoms of nervous system disorders include headache, nausea, vomiting, weakness, mood swings, and fever. Symptoms specific to the nervous system include the following:

• ▪ Disturbance in motor function (or ability to move), including:

  • 1. Stiffness in the neck, back, or extremities

  • 2. Inability to move any part of the body

  • 3. Seizures or convulsions

  • 4. Paralysis

• ▪ Disturbance in sensory function (or ability to sense or feel), including:

  • 1. Visual difficulties

  • 2. Inability to speak

  • 3. Paralysis

• ▪ Alteration in mental alertness or cognitive function, including:

  • 1. Extreme or prolonged drowsiness

  • 2. Stupor, unconsciousness, or coma

  • 3. Amnesia or extreme forgetfulness

DIAGNOSTIC TESTS

A neurologic examination includes testing motor, sensory, and mental function. This examination is often performed on any individual presenting with an injury to the head, neck, or spinal column or exhibiting neurologic symptoms. Motor testing includes checking reflexes, gait, and posture. Sensory testing includes checking the ability to feel, using pinprick or application of heat, cold, or vibration. Ability to see and smell also can be part of sensory testing. Testing of mental or cognitive function includes asking simple questions related to name, occupation, and location. Further testing might include simple math problems or questions about current events.

   The most important laboratory test in a neurologic examination is the analysis of cerebrospinal fluid (CSF). The fluid is examined under a microscope to determine the presence of bacteria, leukocytes, red blood cells, neoplastic cells, and other microorganisms.

   To obtain this fluid, a lumbar puncture must be performed, a procedure that consists of positioning the affected individual on his or her side in a knee-chest position to widen the vertebral disk space, inserting a spinal needle into the meningeal space around the spinal cord, and withdrawing CSF. During the procedure, a special manometer might be connected to the spinal needle so intracranial pressure (ICP) can be measured.

PHARMACOLOGY HIGHLIGHT Common Drugs for Neurologic Disorders

   Because the skull is a rigid structure, any increase in the size of the brain tissue by swelling, tumor, infection, or hematoma will cause an increase in ICP. If pressure becomes too high, the brain will herniate or move downward through the foramen magnum, the only opening available. When this occurs, coma and rapid death can occur because this places pressure on vital centers in the brain stem.

   Radiologic examinations include X-rays of the skull and vertebral column for fractures and other abnormalities. A myelogram, or picture of the spinal cord, might be used for diagnosis of a tumor, nerve root compression, herniated nucleus pulposus (HNP), or herniated disk. Angiograms can help determine vessel occlusion and hematomas in individuals exhibiting symptoms of cerebrovascular accident or stroke.

   Electroencephalography (EEG) measures electrical brain activity. A damaged area of the brain might exhibit abnormal electrical activity as might occur with cerebrovascular accident and epilepsy. EEG is also used to determine brain death.

   Computerized tomography (CT) and magnetic resonance imaging (MRI) scanning are both valuable tools to assess the anatomy of the brain and spinal cord.

COMMON DISEASES OF THE NERVOUS SYSTEM

The diseases of the nervous system can range from mild to severe, depending on the particular condition. Age-related factors can influence the severity of the disease, but many nervous system disorders can affect the individual at any age.

Infectious Diseases

Infections of the nervous system are more common in the young but can be found in older adults as well. Early diagnosis and treatment are essential to reduce the permanent neurologic deficits that can result from the infection.

ENCEPHALITIS

▪ DESCRIPTION. Encephalitis is an inflammation of the brain tissue.

▪ ETIOLOGY. Encephalitis is caused by a variety of microorganisms, including bacteria and viruses, or as a complication of measles, chicken pox, or mumps. Such viruses can be spread also by mosquitoes and carried from animal to human or from human to human.

▪ SYMPTOMS. Symptoms include headache, elevated temperature, and a stiff neck and back but can progress to lethargy, mental confusion, and even coma.

▪ DIAGNOSIS. Encephalitis is usually diagnosed by finding the causative agent in spinal fluid obtained by lumbar puncture.

▪ TREATMENT. Treatment is supportive. Antiviral medication might be effective in some types of encephalitis, but prognosis is guarded because some forms of encephalitis have a high mortality rate. Severe encephalitis can leave the individual with permanent neurologic impairment.

▪ PREVENTION. Prevention is related to avoiding transmission of the disease by mosquitoes. Activities include avoiding outdoor activity when mosquitoes are active—usually near or after dark—wearing protective clothing with long sleeves and long pants, and using repellents that contain DEET.

Consider This …

The female mosquito is the only one that bites. The male mosquito feeds on flower nectar, but the female needs blood proteins in order to produce fertile eggs. The piercing bite mixed with the mosquito saliva creates the stinging skin irritation associated with a mosquito bite.

MENINGITIS

▪ DESCRIPTION. Meningitis is inflammation of the meninges, the covering of the brain and spinal cord.

▪ ETIOLOGY. Meningitis can be caused by anything that causes an inflammatory response, including bacteria, viruses, fungi, and toxins such as lead and arsenic. Some forms of meningitis are more contagious and more lethal than other forms of the disease. The most common cause of meningitis is bacterial invasion by Neisseria meningitides. Bacteria and viruses usually reach the meninges after invading and infecting other parts of the body such as the middle ear, sinuses, and upper respiratory tract; or they can be carried to the meninges in the blood, as in septicemia.

▪ SYMPTOMS. Symptoms of meningitis often include a sudden onset of high fever, severe headache, photophobia (fear of light), and a stiffness in the neck that resists bending the neck forward or sideways (nuchal rigidity). As the disease progresses, drowsiness, stupor, seizures, and coma might occur.

▪ DIAGNOSIS. Diagnosis is usually confirmed by finding the causative agent in the spinal fluid obtained by lumbar puncture.

▪ TREATMENT. Antibiotic treatment of bacterial meningitis is usually quite effective. Other treatments include antipyretics; anticonvulsive medications; and a quiet, dark environment. If untreated, meningitis can be fatal, especially in infants, children, and older individuals. It can cause permanent neurologic damage in children, leading to hearing loss, learning and developmental challenges, and epilepsy. Good hand washing practices can help prevent the spread of the disease.

▪ PREVENTION. Good hand washing helps reduce exposure to infectious organisms. Avoiding those who are infected is also a preventive activity.

POLIOMYELITIS

▪ DESCRIPTION. Poliomyelitis, or polio, is a viral infection affecting the brain and spinal cord. Polio was a major crippling and life-threatening disease affecting children prior to the development of a vaccine in the 1950s. Immunization programs since that time have virtually eliminated the disease in the United States.

▪ ETIOLOGY. The poliomyelitis virus enters the body through the mouth and nose. It crosses the gastrointestinal tract into the blood and then travels to the brain and spinal cord. The virus is spread by oro-pharyngeal secretions and by infected feces.

▪ SYMPTOMS. Symptoms of polio include muscle weakness, neck stiffness, and nausea and vomiting. As the disease progresses, muscles atrophy and deteriorate. Muscles of the arms, legs, and respiratory system can become paralyzed.

▪ DIAGNOSIS. Diagnosis is made by clinical examination and confirmed by culturing the virus from the throat, feces, or spinal fluid.

▪ TREATMENT. Treatment is supportive and in cludes analgesics and bed rest during the acute phase. Long-term physical therapy and limb braces might be needed. If the respiratory system is involved, mechanical ventilation might be necessary.

   Ten to forty years after the initial polio attack, many survivors experience postpolio syndrome (PPS), characterized by further weakening of muscles that were previously affected by the polio infection. Symptoms can include joint pain, fatigue, and increasing skeletal deformities such as scoliosis. The problems caused by PPS usually mirror the severity of the original polio attack. If the original attack was not severe, the PPS condition is usually not bad. PPS tends to affect females more often than it does males. This is not an infectious condition, and it is rarely life-threatening.

▪ PREVENTION. The most effective prevention is with polio vaccine.

TETANUS

▪ DESCRIPTION. Tetanus is a highly fatal infection of nerve tissue.

▪ ETIOLOGY. Tetanus disease is caused by the Clos-tridium tetani bacterium. The effects of the toxin produced by this bacterium on the CNS lead to voluntary or skeletal muscle contraction.

▪ SYMPTOMS. The first symptom is typically a stiffness of the jaw, commonly called lockjaw, and is due to strong jaw muscle contractions. This disease affects both the musculoskeletal system and the nervous system.

   More detailed information about tetanus is found in Chapter 6, “Musculoskeletal System Diseases and Disorders.”

RABIES

▪ DESCRIPTION. Rabies is an often fatal encephalomyelitis.

▪ ETIOLOGY. Rabies is caused by a virus and primarily affects animals such as dogs, cats, foxes, raccoons, squirrels, and skunks but can be transmitted to humans through a bite by an infected animal. Like tetanus, this virus travels slowly to the spinal cord and brain, so the location of the bite is significant. Incubation time is from 1 to 3 months. Shorter incubation times are related to the position of the bite, making bites to the face and neck more serious than those to the extremities.

HEALTHY HIGHLIGHT Polio Vaccine Precautions

There are three distinct polioviruses, designated as types 1, 2, and 3. Dr. Jonas Salk developed an injectable vaccine against only one form of polio, so that vaccine is called a monovalent vaccine. It used dead virus to stimulate the production of antibodies against polio. Dr. Albert Sabin later developed an oral vaccine (trivalent oral polio vaccine [TOPV]) against all three forms of the virus; that vaccine is, therefore, called a trivalent vaccine and is a live vaccine using weakened virus to stimulate antibody production.

   Immunosuppressed individuals must follow precautions with polio vaccines. Immunosuppressed individuals include those who are:

• ▪ Affected with chronic disease.

• ▪ Taking chemotherapy.

• ▪ Receiving radiation treatments.

• ▪ Taking immunosuppressive medications for organ transplants.

• ▪ On long-term steroid treatment.

   Precautions for immunosuppressed individuals include the following:

• ▪ Do not take the live trivalent vaccine because this can lead to contracting polio.

• ▪ Do not change diapers or come in contact with feces of children recently treated with TOPV.

• ▪ Do not come in contact with nasal secretions or vomitus of children recently treated with TOPV.

HEALTHY HIGHLIGHT CDC Recommends Tdap for All Ages

The Centers for Disease Control and Prevention (CDC) now recommends the Tdap (tetanus, diphtheria, and acellular pertussis) shot be given to adults age 65 and older. Previously, the recommendation was for older adults only if they had close contact with infants under age 1 and if they had not been vaccinated with Tdap before. Pertussis cases have been increasing during the last 30 years and peaked in 2010. About 700 of these cases involved older adults. There are two Tdap vaccines on the market, but only one (Boostrix®) is approved by the Food and Drug Administration for older adults.

Source: Lowes (2012).

▪ SYMPTOMS. Symptoms of rabies include fever, pain, paralysis, convulsions, and rage. In animals, a change in temperament is often noticed. Wild animals can become friendly, and family pets can become aggressive. Another classic symptom is spasm and paralysis of the muscles of swallowing. The sight of water or attempting to drink water causes throat spasms, leading to hydrophobia (hydro = water, phobia = fear). Inability to swallow also causes a drooling of frothy saliva, an identifying symptom in animals.

▪ DIAGNOSIS. Diagnosis is based on a history and physical exam, observing for symptoms of muscle spasms, stiffness, and pain. Laboratory tests are not helpful with diagnosis.

▪ TREATMENT. Treatment of rabies includes immediate washing of the area with soap and water, followed by medical attention. A series of antirabies injections must be given before the virus has had time to reach the brain. Any animal bite needs to be investigated immediately. The biting animal should be confined and placed under observation for symptoms of rabies, and viral cultures should be obtained. If the animal cannot be captured and must be killed, care should be taken not to destroy the head because the brain must be examined for presence of disease. If the animal cannot be found, the injured individual will need to take the series of injections immediately.

   There is no cure for rabies. Treatment is palliative and includes strong muscle relaxants to reduce convulsions. Untreated cases end with severe convulsions and respiratory arrest. Death usually occurs within 2 to 5 days after onset of symptoms.

▪ PREVENTION. Prevention of rabies begins with vaccination of family pets and education of children in recognizing and avoiding animals with rabid symptoms.

SHINGLES

▪ DESCRIPTION. Shingles is an acute viral disease. It is fairly common in the elderly, with approximately 50% of people over age 80 having an episode of shingles.

▪ ETIOLOGY. Shingles is caused by herpes zoster, the same virus that causes chicken pox. The only difference between chicken pox and shingles is the level of the affected individual's immunity. Chicken pox usually appears in children with little or no immunity, and shingles occurs in adults with limited immunity. It is thought that herpes zoster virus is a chicken pox virus that has been dormant, usually for years, after recovery from chicken pox. This virus tends to flare up or become active during periods of stress or immunosuppression caused by other disease processes, trauma, and aging.

▪ SYMPTOMS. Shingles is characterized by an itching, painful, red rash, and small vesicles or blisters that follow the course of a sensory nerve (Figure 15-4). The resulting neuritis or inflammation of the nerve results in a stabbing, sharp pain that usually is more severe at night. Symptoms can last from 10 days to several weeks. The pattern of rash and blisters usually appears on the body trunk and runs toward the midline but also can appear on the face, causing severe conjunctivitis. A more rare form of shingles is Zoster san herpes, or shingles without the typical rash. Pain may run more front to back and is often mistaken for a heart attack.

FIGURE 15-4 Shingles: vesicles follow a nerve pathway.

▪ DIAGNOSIS. Diagnosis is made on the basis of the appearance of lesions. A viral culture or blood test for the herpes virus can be performed to confirm the diagnosis.

▪ TREATMENT. There is no cure for shingles. Treatment is symptomatic and involves administration of antiviral medication (acyclovir, valacyclovir, famciclovir), analgesics (acetaminophen, aspirin, ibuprofen, and opioids, like codeine, for severe pain), topical antibiotics applied to prevent infections of the open blisters, and antipruritics (medications to reduce itching).

▪ PREVENTION. Zostavax®, a vaccine to prevent shingles, has been available for individuals over age 60 since it was licensed by the Food and Drug Administration (FDA) in 2006. The vaccine is not a treatment for shingles.

Vascular Disorders

Vascular disorders of the nervous system can be quite severe, causing long-term debility. Some vascular disorders can be prevented or reduced in severity by lifestyle changes.

CEREBROVASCULAR ACCIDENT (CVA)

▪ DESCRIPTION. CVA is commonly called a stroke. It is a major cause of death in people over 50 years of age.

Consider This …

On average, someone in the United States has a stroke every 40 seconds and someone dies from a stroke every 3 minutes.

▪ ETIOLOGY. CVA is due to poor blood supply to the brain. A common causative factor is arteriosclerosis. A CVA is to the brain what a heart attack is to the heart—lack of blood flow to the brain causes brain tissue death. The three common causes of poor blood supply or lack of blood flow are:

• Cerebral thrombus a clot in a brain artery and the most common cause of vessel occlusion. Thrombus formation usually occurs in an area where the vessel is narrowed by arteriosclerosis. Symptoms usually appear gradually until blood flow is inadequate.

• Cerebral embolism usually due to a small piece of a thrombus or arterial plaque breaking loose and traveling in the artery until it wedges and occludes the vessel. Symptoms usually appear quite suddenly.

• Cerebral hemorrhage the rupture of an artery, filling the surrounding brain tissue with blood. Cerebral hemorrhage is usually due to hypertension and arteriosclerosis (see “Arteriosclerosis and Atherosclerosis” in Chapter 8, “Cardiovascular System Diseases and Disorders”), which cause the vessel to tear and hemorrhage. Another cause of cerebral hemorrhage is a weakened artery due to an aneurysm. Symptoms are very sudden with hemorrhage.

▪ SYMPTOMS. When an area of the brain loses blood supply, the individual suddenly loses consciousness and can die or have permanent neurologic disability. About one-third of individuals with a CVA die. Some survive without functional disability, and others might have mild, moderate, or severe disability. The symptoms of CVA are numerous, depending on the area of the brain affected and the severity of the occlusion or hemorrhage. Common symptoms include dysphasia (dis-FAY-zee-ah; dys = difficulty, phasia = speaking), dysphagia (dis-FAY-jee-ah; dys = difficulty, phagia = swallowing), hemiparesis (HEM-ee-par-EE-sis; hemi = one half, paresis = paralysis), confusion, and poor coordination (Figure 15-5).

▪ DIAGNOSIS. Diagnosis of CVA is made and confirmed by physical examination, EEG, and CT or MRI scan. One indicator of the location of brain damage is shown by the pattern of hemiparesis, if present. Hemiparesis affecting the left side is indicative of right-sided brain injury, whereas hemiparesis affecting the right side is indicative of left-sided brain injury. Symptoms of right- and left-sided brain damage vary to some degree (Figure 15-6).

▪ TREATMENT. Treatment of CVA depends on the severity of the stroke and the symptoms. Anticoagulant and hypertensive medications can be given to control the formation of clots and to lower blood pressure. For those individuals with physical disability, a rehabilitation program, including the needed services of physical therapy and speech therapy, must be set up early and continued until the individual has gained maximum potential.

FIGURE 15-5 CVA: facial features.

FIGURE 15-6 Symptoms of right and left CVA vary to some degree.

▪ PREVENTION. Prevention of stroke is directed toward avoiding risk factors that include:

• 1. Smoking

• 2. High-fat diet

• 3. Obesity

• 4. Lack of exercise

These factors also play a role in arteriosclerosis, a main cause of CVA.

   Early detection and treatment of occluded arteries can aid in prevention of some types of CVA. Carotid artery screening involves a physician auscultating the carotid arteries and listening for vessel narrowing. As blood rushes through a narrowed vessel, a rushing sound called a bruit (BREW-ee) can be heard. Ultrasound imaging can also be performed to determine the condition of the vessel. Surgical intervention to open the vessel might prevent CVA and includes removal of plaque in the carotid arteries to improve blood flow and reduce the risk of a thrombus. This surgical procedure is called a carotid endarterectomy.

TRANSIENT ISCHEMIC ATTACK (TIA)

▪ DESCRIPTION. TIAs are sudden, mild mini-strokes.

▪ ETIOLOGY. TIAs are due to insufficient blood supply to the brain. They can serve as a warning of an impending stroke and are often due to artery narrowing by arteriosclerotic plaque.

▪ SYMPTOMS. Symptoms, like those of CVA, depend on the area of the brain that is affected. Some common symptoms are weakness of an arm, leg, or both; dizziness; slurred speech; and a mild loss of consciousness. Total loss of consciousness usually does not occur. Symptoms usually subside within a few minutes to an hour.

▪ DIAGNOSIS. Symptoms can be completely resolved by the time medical advice is sought. The diagnosis is made on the medical history and physical examination including a neurologic exam. Blood pressure is also checked for hypertension. A stethoscope may be placed over neck veins (auscultation) to determine blood flow irregularities. Arteriograms can locate suspected vessel blockage or occlusion. A CT scan of the head might also be part of the diagnostic testing.

▪ TREATMENT. Arteriograms showing blocked blood flow can be followed up with surgery to open vessels or bypass blockage. Carotid endarterectomy is one of the more common surgeries to correct blood flow for TIA.

COMPLEMENTARY AND ALTERNATIVE THERAPY Too Many Supplements Could Be Harmful, but Not Always

Many individuals today are taking mega-doses of vitamins for a variety of reasons. Some believe it gives them more energy, and others believe it might cure their disorders. However, a group of doctors and researchers warn the consumer that taking these large doses of vitamins might actually be harmful to their health. They state that large amounts of vitamin D and calcium are unnecessary and large amounts of vitamin E could increase a person's risk of hemorrhagic stroke by 22%. However, they also note that it might reduce the risk of ischemic stroke by 10%. B complex vitamins have been shown to help maintain cognitive function. Perhaps the best warning to the consumer is to use these products wisely, be aware of side effects, read the labels, and communicate with a primary care provider about taking supplements.

Source: Challem (2011).

▪ PREVENTION. Quitting smoking is the best preventive measure. Knowing risk factors and living a healthy lifestyle are also helpful preventive measures.

Functional Disorders

Functional disorders of the nervous system include degenerative disk disease, headache, epilepsy, and Bell's palsy. These conditions, although varying in severity, are some of the most common problems of the system. The cause of the disorder might be found, but in many cases, it is unknown. Treatment of structural disorders is directed toward the relief of symptoms and assisting the individual in maintaining maximum function in activities of daily living.

DEGENERATIVE DISK DISEASE

▪ DESCRIPTION. Degenerative disk disease is actually a degeneration, or wearing away, of the intervertebral disk of the musculoskeletal system, but the results so severely affect the neurologic system that it will be considered in this chapter.

▪ ETIOLOGY. The wearing away of the disk between the vertebrae of the back allows the vertebrae to bump or rub against each other. As these vertebrae move closer together, the opening for the spine and nerve roots becomes smaller, causing pressure on the nerves. The condition of narrowing of nerve root openings in the spinal column is called spinal stenosis (stenosis = narrowing).

▪ SYMPTOMS. Common symptoms include difficulty walking and radiating pain in the back and in one or both legs. This pain often follows the nerve path and can be intractable (difficult to stop or control). Degenerative disk disease usually affects older individuals but can be related to trauma or congenital defects in younger individuals.

▪ DIAGNOSIS. Diagnosis is made on the basis of clinical history, X-ray, myelography, CT, or MRI.

▪ TREATMENT. Treatment initially involves resting the back and legs. A back brace might be beneficial. Long-term treatment involves analgesics, anti-inflammatory medications, and exercise to ease the pain. A laminectomy, surgery to remove part of the vertebrae and widen the nerve root opening, can be the treatment of choice. In severe cases, surgery to fuse the vertebrae and free the nerve root can be performed. Often, older individuals affected with degenerative disk disease and spinal stenoses are not medically stable enough to endure surgery.

▪ PREVENTION. Since degenerative disk disease primarily affects the elderly due to the aging process, many cases cannot be prevented. Moderate exercise, especially daily walking programs, and good nutrition can help slow or stop painful symptoms.

HEADACHE

▪ DESCRIPTION. Headache, or cephalalgia (SEF-ah-LAL-jee-ah; cephal = head, algia = pain), is one of the most common disorders of humans. It is usually a symptom of another disease rather than a disorder in and of itself. Disorders that typically have headaches as a symptom can include sinusitis, meningitis, encephalitis, hypertension, anemia, constipation, premenstrual tension, and tumors, to name only a few. Most headaches are not related to disease but are basically caused by two mechanisms:

• ▪ Tension on the facial, neck, and scalp muscles

• ▪ Vascular changes in arterial size (dilation or constriction) of the vessels inside the head

▪ ETIOLOGY. Many factors produce headaches, including allergies, stress, noise, toxic fumes, lack of sleep, and alcohol consumption.

▪ SYMPTOMS. Headaches can be acute or chronic and can affect different areas of the head. The pain can range from mild to unbearable and incapacitating; it can be constant or intermittent and might be described as pressure, throbbing, or stabbing. Interestingly, brain tissue does not contain sensory nerves, so the sense of pain must come from the pain receptors in the meninges, facial tissue, or scalp. Some of the more common types of headaches include:

• Tension headache caused by stress, strain, and tension on the facial, neck, and scalp muscles. Pain is typically in the occipital area.

• Cluster headache can be caused by stress, emotional trauma, or unknown reasons. These headaches occur at night after falling asleep. The pain is generally a severe, throbbing pain behind the nose and one eye. The skin in this area becomes reddened, and the nose and eye water. The pain generally subsides after 1 or 2 hours but might recur several times during the night.

• Post-lumbar puncture headache a severe headache affecting up to 40% of individuals, following a lumbar puncture. It is thought to be due to leakage of spinal fluid through the needle puncture site. This type of headache is often prevented by positioning the individual flat in bed without a pillow for 2 or 3 hours following this procedure.

• Migraine headache a severe, incapacitating headache commonly accompanied by nausea, vomiting, and visual disturbances. Individuals affected by migraines can experience a visual aura, a sensation that precedes the event, including flashing light, dim vision, or photophobia. This type of headache can begin in adolescence and diminish in intensity and frequency with age. Migraine headaches occur twice as often in women than in men. The cause is still unknown, although they tend to run in families, suggesting some type of inheritance pattern. Some foods that trigger migraines are chocolate, wine, and cheese. It is also thought that these are vascular headaches caused by altered arterial blood flow.

▪ DIAGNOSIS. Diagnosis of the cause of headache depends on individual history and physical examination. Testing can include X-ray, EEG, and MRI and CT scans.

▪ TREATMENT. Headache treatment depends on the cause, severity, and frequency of occurrence. Often, lifestyle changes, such as improvements in diet, sleep, and exercise, help. Pain medications may be over the counter, such as acetaminophen (Tylenol®) or ibuprofen. Prescription pain medication and antinausea medications might also be needed.

▪ PREVENTION. Diet and lifestyle changes and stress reduction are measures that can help prevent headaches. Severe headaches might require prescription medication.

EPILEPSY

▪ DESCRIPTION. Epilepsy is a chronic disease of the brain, characterized by intermittent episodes of abnormal electrical activity in the brain, activity that might be compared to an arrhythmia of the heart.

▪ ETIOLOGY. The cause of epilepsy can be due to brain tumors, neurologic disease, or scar tissue in the brain due to trauma or stroke. More commonly, the cause cannot be determined during the individual's life or even on autopsy.

▪ SYMPTOMS. The most noted symptom of epilepsy is a convulsive seizure. A convulsion is an abnormal muscle contraction. A seizure is actually a sudden attack, but it is commonly used to indicate a convulsive seizure. Not all seizures are characterized by convulsions, and not all convulsions are due to epilepsy. Convulsions can occur in a nonepileptic individual due to conditions such as excessive temperature (hyperpyrexia), hypoglycemia, hypocalce-mia, and drug or alcohol toxicity.

GLIMPSE OF THE FUTURE High-Vitamin Diets = Better Test Scores?

Your diet could affect your scores on thinking tests according to recent research. Diets high in vitamins B, C, D, and E and omega-3 fatty acids and low in trans-fats may be good for brain health. Studies have shown that these vitamins are the most supportive of healthy brain aging. The studies were done on older adults who did not have other common diseases of their age group such as diabetes or high blood pressure. The participants were given thinking tests, and their scores were compared with laboratory tests analyzing their nutrient levels. The studies found that diets high in vitamins and omega-3 fatty acids were good for brain health. A diet high in trans fats was determined to be most unfavorable for brain health. Further research needs to determine how much of an individual's declining mental ability is related to diet and how much to other factors such as environment or other diseases. What will future research tell us about our diet and health?

Source: Doheny (2011).

   The most common types of seizures are:

• ▪ Petit mal These seizures are also called absence seizures and commonly occur in children; they are often outgrown during puberty, but they can last a lifetime. These seizures consist of a brief change in the level of consciousness without convulsions. The involved individual might show symptoms of blank staring, blinking, and twitching of the eyes or mouth, or all these. The individual might remain seated or standing with loss of awareness of surroundings. Often, the seated individual appears to have only a loss of attention or absentminded-ness. Episodes often last only a few seconds but can occur multiple times during the day.

• ▪ Grand mal These seizures are the type most often thought of as epilepsy. They are characterized by convulsions, loss of consciousness, urinary and fecal incontinence, and tongue biting. Epileptic individuals often perceive an aura with grand mal seizures, allowing time to lie down or call for support. Auras can include tingling of the fingers, ringing in the ears, and visual disturbances. Grand mal seizures often begin with a crying out as the contraction of the respiratory muscles forces exhalation, followed by generalized rhythmic contractions of the skeletal muscles of the body, arms, and legs. Contractions can last 1 to 2 minutes, but consciousness will return more slowly. The involved individual is often weak, drowsy, and confused and has no memory of the seizure event.

• ▪ Status epilepticus is a life-threatening event, a state of continued convulsive seizure with no recovery of consciousness. This is a medical emergency because treatment is needed to prevent cerebral anoxia and possible death.

▪ DIAGNOSIS. Diagnosis of epilepsy is made on the basis of EEG, CT, and cerebral angiograms. EEG can reveal altered brain activity; CT can indicate alteration in brain structure, including tumors; and cerebral angiograms can reveal alteration in blood flow. Blood tests can be performed to indicate disorders of hypo-glycemia and drug or alcohol toxicity.

▪ TREATMENT. Anticonvulsive medications are the treatment of choice for epilepsy. Close monitoring and adjustment of medications are needed to get the best effect. Medications are effective in preventing or reducing seizures 80% of the time. Education and emotional support of the affected individual and family members are necessary because this disease is often feared due to lack of education. The goal for epileptic individuals should be maintenance of a normal lifestyle.

▪ PREVENTION. Because the cause of epilepsy in many cases is not clear, it is not possible to prevent it. In the case of epilepsy brought on by head injury, prevention measures include wearing a seat belt in the car and a helmet when riding a motorcycle, ATV, bike, or horse or while skating or skiing.

HEALTHY HIGHLIGHT First Aid for Seizures

Aseizure is a sign of a malfunction of some part of the brain's electrical system. Most seizures in individuals diagnosed with epilepsy are not emergencies, but they could be in others. It is always wise to call for assistance (medical personnel) when unsure.

   In the event of a seizure, complete the following steps:

• ▪ Look for a medical ID.

• ▪ Loosen tight clothing.

• ▪ Protect the individual from harm or nearby hazards.

• ▪ Protect the head by placing a cushion or padding under it.

• ▪ Do not attempt to place a tongue blade, any hard object, or your fingers in the individual's mouth.

• ▪ Turn the individual to a side-lying position.

• ▪ Avoid tightly restraining the individual.

• ▪ Stay with the individual until other assistive personnel arrive.

• ▪ Reassure the individual and offer assistance as consciousness returns.

BELL'S PALSY

▪ DESCRIPTION. Bell's palsy is a disease affecting the facial nerve (seventh cranial nerve), causing unilateral (one-sided) paralysis of the face. It commonly occurs in individuals 20 to 60 years of age. Bell's palsy can affect either side of the face, and both genders are affected equally. There appears to be an increased risk for pregnant women and those with an upper respiratory infection, influenza, and diabetes.

▪ ETIOLOGY. This disease is idiopathic, but possible causes include autoimmune problems and viral disease.

▪ SYMPTOMS. Symptoms include a drooping weakness of the eye and mouth, with inability to close the affected eye and drooling of saliva. The affected individual is unable to whistle or smile and has a distorted facial appearance (Figure 15-7).

▪ DIAGNOSIS. Diagnosis is made on the basis of clinical history and symptoms. An electromyography can be completed to measure voluntary muscle movement and determine the extent of nerve weakness. An MRI scan is helpful also.

▪ TREATMENT. Treatment includes analgesics and anti-inflammatory medications. If the individual is unable to close the affected eye, protection of the eye with a patch and artificial tear medication might be needed. Warm, moist heat, electrical nerve stimulation, and massage can be prescribed to prevent facial muscle atrophy. Prognosis for Bell's palsy is good, with most cases resolving spontaneously in 2 to 8 weeks. Plastic surgery might be prescribed to correct the facial deformities caused by chronic disease.

FIGURE 15-7 Facial appearance of Bell's palsy.

▪ PREVENTION. There are no known preventive measures.

PARKINSON'S DISEASE

▪ DESCRIPTION. Parkinson's disease is a slow, progressive brain degeneration, usually developing in individuals in their late 50s and 60s. Parkinson's affects men more often than it does women.

▪ ETIOLOGY. The cause is unknown, but individuals with Parkinson's have been found to have a deficiency of the neurotransmitter dopamine in the brain.

▪ SYMPTOMS. Classic symptoms include the following:

• ▪ Rigidity and immobility of the hands and a very slow speech pattern

• ▪ A fine tremor in the hands described as a pill-rolling motion of the fingers

• ▪ An expressionless facial appearance with a fixed stare and infrequent blinking called Parkinson's facies (fay-SHEEZ)

• ▪ An abnormal bent-forward posture that includes a bowed head and flexed arms (Figure 15-8)

FIGURE 15-8 Classic posture in Parkinson's disease.

COMPLEMENTARY AND ALTERNATIVE THERAPY Chinese Herbs for Parkinson's Disease Treatment

Mixtures of herbs have long been the basis of Chinese medicine. Western medicine did not give much credence to these treatments in the past, but new studies have shown many of them to be effective for a variety of illnesses. Parkinson's disease symptoms have been treated by the Chinese for centuries with the herb gou teng or with a combination of herbs. Recent research found that patients with Parkinson's disease who took a combination of herbs, which included gou teng, were able to sleep well and had more understandable speech patterns. A new drug being tested for Parkinsonism treatment has serious side effects, whereas gou teng seems to have no ill effects on the user. Other combinations of herbs are still being tested.

Source: Zukerman (2011).

• ▪ A peculiar gait of short, fast-running steps due to the abnormal posture that makes the individual tend to stumble forward, leading to frequent falls

▪ DIAGNOSIS. Diagnosis is usually easy to make after a thorough history and physical exam. Criteria for Parkinson's disease are bradykinesia and at least one of the following: muscle rigidity, resting tremor, and/or postural instability.

▪ TREATMENT. Treatment of Parkinson's is symptomatic. Dopamine replacement medications can be used; they do not stop the progression of the disease, but they might help with symptoms. Psychological support and physical therapy for muscle soreness are also helpful.

▪ PREVENTION. There is no known prevention for Parkinson's disease.

Dementias

Dementia (dee-MEN-she-ah) is a loss of mental ability due to the loss of neurons or brain cells caused in several ways. One of the most common dementias is senile (old) dementia and is related to degeneration of cells with aging. The most common cause of senile dementia is Alzheimer's disease. Therefore, Alzheimer's and senile dementia are often used synonymously, but in reality, an individual can have senile dementia without Alzheimer's. Vascular dementia also can be considered a form of senile dementia because it tends to occur in older individuals.

ALZHEIMER'S DISEASE

▪ DESCRIPTION. Alzheimer's (ALTZ-high-merz) disease is a form of dementia characterized by the death of neurons and replacement of these neurons by microscopic plaques. It is the most common cause of dementia among older people. The disease usually affects individuals 70 years of age and older. The number of cases increases with age, with an estimated 50% of individuals over age 85 affected.

HEALTHY HIGHLIGHT Not All Hand Tremors Are Caused by Parkinson's Disease

Not all hand tremors are due to Parkinson's disease. The most common tremor type is called “essential” tremor. This type of tremor most often affects the hands, but can affect the voice, legs, and head. Essential tremor is often inherited or of unknown cause. This tremor usually occurs when an individual holds a posture such as holding a fork or holding the arms outstretched. It usually does not occur at rest. β-blocker and anticonvulsant medications may be of some help if the tremors worsen to the point of making day-to-day tasks difficult to perform.

   Short-lived “physiologic” tremors may occur due to stress, anxiety, low blood sugar, thyroid problems, or withdrawal from caffeine or alcohol. The cause and treatment of physiologic tremors should be addressed by a physician.

Source: Mayo Clinic (2012).

▪ ETIOLOGY. The cause of Alzheimer's disease is unknown, but factors being considered are heredity, viral infection, autoimmunity, and aluminum toxicity. Research also shows a higher rate of Alzheimer's in individuals with a history of head trauma.

▪ SYMPTOMS. Symptoms of the disease begin with mild mental impairment characterized by loss of short-term memory, inability to concentrate, and slight changes in personality. As the disease progresses, the affected individual struggles with communication skills, uses meaningless words, and cannot form sentences. Increased forgetfulness and difficulties in communication lead to irritability and agitation. In the final stages, which can take 5 to 10 years to develop, the affected individual's mental and physical capabilities are severely affected. The affected individual becomes restless, disoriented, incontinent, hostile, and combative and is totally dependent on a caregiver. Death is usually due to a secondary cause such as infection.

▪ DIAGNOSIS. Diagnosis cannot be positively made except from autopsy. Initially, a diagnosis can be made on the basis of symptoms after ruling out other brain diseases. In the final stage of the disease, CT or MRI scans might reveal the characteristic brain atrophy and microscopic plaques.

▪ TREATMENT. Treatment is supportive because there is no known cure for Alzheimer's disease. As the individual's capabilities decline, care is focused on safety and maintaining adequate nutrition, hydration, and personal hygiene. Mobility and mental capabilities are supported for as long as possible. Emotional support of family members and caregivers is of primary concern.

▪ PREVENTION. According to the Alzheimer's Research and Prevention Foundation, there is some proof that preventive measures should include avoiding a diet high in trans-fat and saturated fat, especially red meats. Other prevention activities include taking high-potency multiple vitamins and minerals that include folic acid, vitamin E, and at least 2,000 mg of vitamin C.

VASCULAR DEMENTIA

▪ DESCRIPTION. Vascular dementia is caused by atrophy and death of brain cells due to decreased blood flow.

▪ ETIOLOGY. Atherosclerotic plaque is the common cause of decreased blood flow and is common with aging.

▪ SYMPTOMS. Because the atherosclerotic plaques develop slowly, so do symptoms, which progress so slowly that they often go unnoticed by family members until they become quite severe. Symptoms include changes in memory, personality, and judgment. Irritability, depression, and sleeplessness also can occur. Personal hygiene is lacking and is often the sign that alerts family members to the condition. The affected individual can become disoriented and lost in familiar surroundings.

▪ DIAGNOSIS. Diagnosis is made on the basis of a history and physical and blood flow testing. Arterio-grams of the carotid and cerebral arteries will reveal narrowing of vessels, stenosis, and arteriosclerotic plaques.

▪ TREATMENT. Treatment is aimed at increasing blood flow to the brain. If the cerebral arteries are involved or narrowed, medications may help improve blood flow. Carotid artery plaques can be surgically cleaned by a carotid endarterectomy (END-ar-ter-ECK-toh-me; endo = inside, arter = artery, ectomy = excision of). Prognosis depends on the effectiveness of treatment and the amount of brain cell death. If treatment is not possible or effective, or if a large amount of brain tissue has been lost, the affected individual will become progressively more demented and might need institutionalization for care.

▪ PREVENTION. The best preventive measures are to quit smoking, lead a healthy lifestyle, and control hypertension.

HEAD TRAUMA DEMENTIA

▪ DESCRIPTION. Head trauma can damage any part of the brain. This term fails to capture all the symptoms and long-term disabilities that can be related to such trauma. Males experience head injuries more often than females, with the most injuries occurring in those age 14 to 24 years. Very young children commonly have the worst outcomes.

▪ ETIOLOGY. Head trauma dementia is due to death of brain cells related to head trauma. One type is Boxer's dementia, caused by repeated blows to the head as in the sport of boxing. Other types of trauma can be those sustained in accidents, especially motor vehicle accidents, and sports-related activities. The death of brain cells can be caused by the injury itself or by edema and increased ICP, which decreases or halts blood flow to brain cells, leading to cell death.

▪ SYMPTOMS. Symptoms of head trauma dementia include a prolonged or permanent decrease in mental intellect, cognitive function, or both. The affected individual might be unable to perform activities that were easily completed prior to the injury. There are often symptoms of loss of the ability to reason, remember, and show appropriate emotions and behaviors following such injury. Changes in personality are not uncommon. Chronic psychological trauma can bring about major life changes, mania, major depression, and post-traumatic stress and anxiety disorders.

▪ DIAGNOSIS. Diagnosis is made on the basis of history, cranial X-rays, and MRI and CT scans.

▪ TREATMENT. Treatment is aimed at correcting the damage if possible, preventing further damage, and maintaining the existing healthy tissue. Dead brain cells cannot be replaced, so damage is permanent. Therapy and rehabilitation are needed to regain as much function as possible. Individuals suffering severe head trauma might need institutionalization for long-term care.

▪ PREVENTION. Head injury is often easy to prevent with proper use of protective equipment. Preventive activities include:

• ▪ Wearing seat belts in automobiles.

• ▪ Wearing a helmet when riding bikes, ATVs, and skateboards.

• ▪ Wearing work-related safety equipment along with hard hats when needed.

• ▪ For elderly individuals, altering the surroundings by removing rugs or furniture that might slide easily and cause falls.

SUBSTANCE-INDUCED DEMENTIA

▪ DESCRIPTION. This type of dementia is often cured because the cause of the dementia is curable. In some cases of substance abuse dementia, the individual might not have dementia at all but, rather, suffer from severe depression.

▪ ETIOLOGY. Substance-induced dementia is due to brain cell death caused by toxicity from drugs and toxins. This type of dementia can be caused by repeated exposure to, or use or abuse of, certain substances. Commonly, those substances include alcohol, cocaine, heroin, lead, mercury, and fumes of paints, paint thinners, and insecticides, to name only a few. Brain cell death often persists long after the exposure to the substance ends.

▪ SYMPTOMS. Symptoms of mental impairment and decreased cognitive ability can be permanent and often worsen over a period of time.

▪ DIAGNOSIS. Substance abuse dementia is usually difficult to diagnose. A history and physical exam along with family and caregiver history of the individual's symptoms and history are helpful. A mental health exam is often needed.

▪ TREATMENT. Once properly diagnosed, treating the dementia is usually a matter of removing the toxin (drugs, alcohol, fumes, or insecticides). Depending on the degree of dementia, removing the toxin might not restore normal function.

▪ PREVENTION. Avoiding the toxin prevents this type of dementia.

Sleep Disorders

Sleep may be described as a necessary state of unconsciousness. It is thought that sleep is a period of time during which the body is actively restoring and repairing itself because an increased amount of growth hormone is released during sleep. Sleep also provides a time of recuperation of mental activities. It is believed that there is an increase in metabolic rate in the brain during sleep that allows it to be more alert and efficient during waking hours.

   Sleep deprivation of just one night can lead to changes in personality, lack of muscle coordination, and decreased coping ability. There is a great variability in sleep requirements among individuals and different ages: infants need 16 to 20 hours of sleep every 24 hours. The need for sleep decreases into adulthood, with adults generally requiring between 6 and 9 hours of sleep and older adults requiring even less sleep. Sleep disorders can be due to a variety of causes and can be tested by polysomnography, a procedure measuring a variety of physical variables related to sleep.

Consider This …

Humans can live longer without food than without sleep. If water is provided, a person can live a month or two without food, but the human body will shut down and die after only 11 days or so of total sleep deprivation.

INSOMNIA

▪ DESCRIPTION. Insomnia is the most common sleep disorder in the United States, with about one-third of the adult population experiencing it at some time. Insomnia is the perception or feeling of inadequate or poor sleep, the inability to fall or stay asleep, or waking up too early in the morning. The affected individual arises physically and mentally tired, irritable, and anxious. Insomnia is more common in females and occurs increasingly with age.

▪ ETIOLOGY. The cause of insomnia can be related to stress, pain, fear, depression, and cardiovascular or thyroid disorders. Drugs such as caffeine, alcohol, nicotine, and bronchodilators also can cause insomnia. Eventually, the fear of being unable to fall asleep can become a cause.

▪ SYMPTOMS. The symptom is sleeplessness, often leading to fatigue and irritability. The diagnostic definition of insomnia is sleeplessness for more than 1 month that is interfering with the individual's social or work habits.

▪ DIAGNOSIS. Diagnosis is determined by taking a careful account of an individual's sleep history. Referral to a sleep lab might help if a breathing disorder is suspected.

▪ TREATMENT. Treatment consists of identifying and removing the cause(s). One can develop a sleep routine with a scheduled bedtime and awakening time, and counseling might be needed to assist the individual in managing or reducing stress and anxiety. The affected individual is encouraged not to worry about when and how much he or she sleeps and to take naps and sleep as they can rather than build up anxiety about sleeping at night. The total amount of sleep in 24 hours is more important than the sleeping schedule.

▪ PREVENTION. Prevention centers on living a healthy lifestyle, balancing rest, exercise, and recreation with stress management and healthy diet.

Consider This …

Average pillows and mattresses contain millions of fungi and dust mites. Mattresses gain approximately a pound or more per year from dust mites.

SLEEP APNEA

▪ DESCRIPTION. Sleep apnea (AP-nee-ah; a = without, pnea = breathing) is a sleep disorder characterized by periods of apnea or breathlessness.

▪ ETIOLOGY. This condition occurs more frequently in men and might be related to obesity, hypertension, and airway obstruction. Alcohol ingestion and smoking also can be causative factors.

▪ SYMPTOMS. The diagnostic definition of sleep apnea is more than five periods of apnea lasting for at least 10 seconds each per hour of sleep. These breathless periods are followed by sudden gasps or snorts for air. Other symptoms can include (1) excessive daytime sleepiness to the point of falling asleep during driving, at work, or in the middle of a conversation; (2) extreme snoring that might not awaken the affected individual but easily awakens family members; and (3) personality changes, depression, and impotence. Sleep apnea can be divided into three categories:

• ▪ Obstructive apnea, caused by nasal obstruction

• ▪ Central apnea, caused by a disorder in the brain's respiratory control center

• ▪ Mixed apnea, a combination of both obstructive and central apnea

▪ DIAGNOSIS. Diagnosis is confirmed by monitoring the affected individual during sleep for apnea and low blood oxygen levels.

▪ TREATMENT. Treatment is based on cause. Obstructive types and mixed types are treated with weight-loss therapy and, if needed, surgery to correct nasal obstruction. Individuals affected by obstructive apnea also might benefit from oxygen administration, oral appliances, adjustable airway pressure devices, and continuous positive airway pressure (CPAP) devices during sleep. Central apnea is more difficult to control and might be treated with medications to stimulate breathing.

▪ PREVENTION. Most cases of sleep apnea can be prevented by maintaining a healthy weight, avoiding alcohol, not smoking, and avoiding environmental smoke.

Consider This …

Staying awake for 17 hours has the same effect on your body as drinking two glasses of wine.

Tumors

Tumors may be classified as benign and malignant. (See Chapter 3, “Neoplasms.”) Benign tumors of the brain often become malignant if surgical removal is not possible. The growth of benign tumors in the confined space of the skull places pressure on the brain tissue and blood vessels, leading to loss of function and death of normal tissue. Tumors can occur in any area of the brain and at any age, although many are fairly age-specific or commonly occur in a particular age group. Gliomas and meningiomas are most common in adults.

BRAIN TUMOR

▪ DESCRIPTION. Brain tumors may be classified as primary or secondary. Primary tumors start in the brain tissue, whereas secondary tumors occur in other areas and metastasize to the brain. Brain tumors in children are commonly primary tumors. Secondary tumors are not called brain tumors; they are named after the organ of origin. In other words, breast tumor that metastasizes to the brain is still called breast cancer with metastasis to the brain. Common sites of secondary tumors that metastasize to the brain include breast and lung.

▪ ETIOLOGY. The cause of primary tumors is unknown.

▪ SYMPTOMS. Symptoms are varied, depending on the area involved, and include headache, vomiting, seizures, mood and personality changes, visual disturbances, and loss of memory.

▪ DIAGNOSIS. Diagnosis is made on the basis of clinical history, symptoms, X-ray examinations, CT and MRI scans, and biopsy. A biopsy is the most definitive study to determine the type of tumor and the best study to assist with treatment and prognosis. Further studies might be needed to determine the primary location of metastatic brain tumors.

▪ TREATMENT. Treatment can include surgery, radiation, and chemotherapy. Treatment and prognosis depend on the type and location of the tumor.

▪ PREVENTION. Reducing or avoiding exposure to radiation, certain medications, and head trauma can benefit prevention.

TRAUMA

Injuries to the brain, neck, and spinal cord are a main cause of disability and death. Trauma to the head can cause edema, increased ICP, hemorrhage, and infection, resulting in brain damage. Injury to the neck and spinal cord can lead to temporary or permanent paralysis.

Concussions and Contusions

▪ DESCRIPTION. A concussion is the less serious of the two conditions and does not involve injury to the brain. A contusion, however, is a physical bruising of the brain tissue. Brain contusions are often accompanied by skull fractures.

▪ ETIOLOGY. A blow to the head caused by an object, fall, or other trauma such as an automobile accident can cause a concussion or contusion.

▪ SYMPTOMS. Both concussions and contusions cause a disruption of normal electrical activity in the brain, which, in turn, causes immediate unconsciousness, often described as being knocked out. This state of unconsciousness can last from a few seconds to several hours, and the affected individual often awakens with amnesia, or loss of memory. Other symptoms are headache, blurred vision, and irritability. The individual might suddenly draw up the knees and begin vomiting.

   The physical bruising of a contusion can lead to the development of a hematoma, increased ICP, and permanent brain damage. If the bruised tissue is in the area of the impact, it is referred to as a coup (COO) lesion. Coup lesions often occur with direct injury such as is incurred from a direct blow to the head. If the injury occurs on the opposite side of the brain, it is called a contracoup (CON-tra-coo) lesion, which often occurs when the head is in motion and is stopped suddenly, causing a rebound effect to the opposite side (Figure 15-9), as is often found in automobile accidents. Contracoup injuries are commonly accompanied by a coup injury at the point of impact.

▪ DIAGNOSIS. Diagnosis of both conditions is made on the basis of a history of the injury, neurologic examination, cranial X-ray, and CT or MRI scans.

▪ TREATMENT. Treatment of a concussion consists of bed rest in a quiet area under direct observation. The individual should be awakened every 2 to 4 hours and observed for changes in consciousness, eye pupil size, mood, and behavior. An individual suffering with a contusion should be hospitalized for continuous monitoring. Analgesic, sedative, and stimulant medications should not be given to individuals with head injuries because these medications can mask symptoms and make assessment difficult.

▪ PREVENTION. Head injury prevention includes activities such as wearing a seat belt in an automobile, wearing helmets with recreational activity, and preventing falls by removing clutter and slippery rugs.

Media Link

View an animation on contracoup injuries on the Online Resources.

Skull Fractures

▪ DESCRIPTION. A skull fracture is a break in a cranial (skull) bone. The greatest danger of a skull fracture is the resulting brain tissue damage (Figure 15-10). Bony fragments can cut into the brain tissue, severing a vessel and causing a hematoma. Brain damage from a fracture can be temporary or permanent.

▪ ETIOLOGY. A fracture can occur with head injuries from falls, a severe blow to the head, automobile accidents, or sports injuries.

▪ SYMPTOMS. The position of the fracture will cause a variety of symptoms. For instance, a fracture near the base of the skull might injure the respiratory center of the brain, causing the individual to stop breathing. Fractures in other areas can lead to hemiparesis and seizures. Another potential problem is infection of the brain tissue through the fracture site.

FIGURE 15-9 Coup and contracoup lesions.

FIGURE 15-10 (A) Common sites and types of skull fractures. (B) Skull fracture (X-ray)

▪ DIAGNOSIS. Diagnosis is made on the basis of clinical history, physical examination, cranial X-rays, and CT scan.

▪ TREATMENT. Treatment depends on the type and position of the fracture. A craniotomy (cranio = skull, otomy = incision) might be performed to relieve ICP due to swelling. Surgical repair of the fracture might be performed if the fractured bone is pressing on the brain tissue. Protective headgear might be needed until the fracture site is healed.

▪ PREVENTION. Preventive actions include practicing safety measures and avoiding risky activities to prevent head injury.

Epidural and Subdural Hematomas

▪ DESCRIPTION. An epidural hematoma is a collection of blood between the skull and dura mater, the thin membrane that covers the brain. Epidural hematomas occur more often in young adult males. A subdural hematoma is a collection of blood between the outer (dura mater) layer and the middle (arachnoid) layer. Subdural hematomas occur twice as often as epidural hematomas.

▪ ETIOLOGY. A blow to the head, such as might be obtained in a fight or accident, is the common cause of an epidural (EP-ih-DER-al); epi = above, dural = dura, outer meninges) hematoma. Blood vessels are ruptured and hemorrhage or seep blood between the bony skull and the first, or outer, meninges, the dura mater (Figure 15-11). Blood usually collects rapidly over a period of hours, pushing the dura away from the inner bony skull.

   A subdural (SUB-DOO-ral) hematoma is usually the result of the head hitting a stationary object, as is often seen with falls, characterized by striking the head on the floor or a solid object. Subdural hematomas are characterized by blood collecting between the outer (dura mater) layer and the middle (arachnoid) layer. Subdural hematomas generally develop more slowly over a period of days.

▪ SYMPTOMS. Symptoms of an epidural hematoma occur within a few hours after injury and can include headache, dilated pupils, nausea, vomiting, and dizziness. As the hematoma grows, the individual might lose consciousness and develop an increase in ICP.

   Symptoms of a subdural hematoma are due to increased ICP. Symptoms might include hemiparesis, nausea, vomiting, dizziness, convulsions, and loss of consciousness.

FIGURE 15-11 (A) Epidural and (B) Subdural hematomas. (C) CT of epidural hematoma. (D) CT of subdural hematoma.

▪ DIAGNOSIS. Diagnosis of a cerebral hematoma is made on the basis of clinical history, cranial X-ray, or CT or MRI scan. Hematomas, generally, are accompanied by a skull fracture.

▪ TREATMENT. Treatment of epidural and subdural hematomas is aimed at decreasing ICP. Pressure can be relieved by a special craniotomy called burr holes to drain the blood and cauterization (KAW-ter-eye-ZAY-shun; electrical burning of tissue) to stop the bleeding. If ICP is treated promptly, prognosis is good. Untreated, increased ICP can be fatal.

▪ PREVENTION. Preventive actions include activities to prevent head injury.

Spinal Cord Injury: Quadriplegia and Paraplegia

▪ DESCRIPTION. The spinal cord is protected by the bony vertebral column. When this column is fractured or injured, the spinal cord also can suffer injury. The spinal cord can be injured at any level, but the mobility of the neck causes this area to be the most vulnerable. The site of the injury, the type of trauma, and the degree of injury will all play a role in determining whether paralysis will occur and whether it will be temporary or permanent. Paralysis of the lower part of the body including both legs is called paraplegia. If the body and both arms and both legs are affected, it is called quadriplegia.

▪ ETIOLOGY. The leading cause of spinal cord injury is automobile accidents. Other causes are gunshot and knife wounds, falls, and recreational and sports injuries.

▪ SYMPTOMS. Injury to the spinal cord can result in varying degrees of loss of movement and feeling below the area of injury. If the damage to the spinal cord is severe, there is little or no hope of regaining movement and feeling. Paralysis, initially, results in the inability to move the extremities; but with time, reflex functions might return, leading to spastic movements. Refer to Figure 15-12 while reading the following material for a better understanding of spinal cord injuries and preventive measures.

   Injury to the neck is common in automobile accidents and sports accidents. Automobile accidents commonly lead to injury in the form of whiplash.

   Injury to the highest level of the cervical spine (C1-C3) is usually fatal. Injuries to the cervical spine or neck area (C1-C4) can lead to quadriplegia (KWAD-rih-PLEE-jee-ah; quadri = four, plegia = paralysis). Quadriplegia is the loss of movement and feeling in the trunk and all four extremities with the accompanying loss of bowel, bladder, and sexual function. Other life-threatening symptoms include hypotension, hypothermia (hypo = low, thermia = heat or temperature), bradycardia, and respiratory problems. In some cases, respirations must be permanently assisted with mechanical ventilation. Injury to the lower cervical spine (C5-C7) can lead to varying degrees of paralysis of the arms and shoulders.

   Injury to the thoracic or lumbar section of the spinal cord can lead to paraplegia (PAR-ah-PLEE-jee-ah; para = beyond or two like parts, plegia = paralysis), a loss of movement and feeling in the trunk and both legs. Loss of bladder, bowel, and sexual function is common. Paraplegia is often the result of a fall or an injury resulting in compression to the lower spine.

▪ DIAGNOSIS. Diagnosis is made on the basis of history of the injury and physical examination along with X-rays, CT scan, MRI, and myelography.

▪ TREATMENT. Treatment of suspected spinal cord injury victims includes seeking emergency medical treatment immediately and not moving the victim unless the surroundings are unsafe or life-threatening as in the case of fire or flood. The head and neck should be moved only in life-threatening situations such as choking or respiratory arrest. Movement at this time should be very cautious. Emergency medical treatment is aimed at maintaining the position of the spine by limiting movement with use of special collars and backboards. The head, neck, and spine are stabilized prior to transporting in an emergency vehicle.

   Hospitalization includes diagnosis and treatment of the injury, including medications, emergency surgery, and, often, immobilization with traction or traction-like devices. Much of the early treatment is aimed at preventing further spinal cord injury.

   Further treatment can include surgery to realign and stabilize the bony spinal column and decompress, or release, pressure on the spinal cord. Early and intensive rehabilitation is necessary for the best prognosis. Generally, the earlier the treatment is begun, the better the prognosis.

   During treatment, medical attention must also focus on preventing problems that arise from immobilization, including muscle wasting, contractures, decubitus (commonly called bed sores), blood clots, and urinary tract infections.

   Long-term care includes rehabilitation and supportive treatment, which might include medications, electric wheelchair, computer devices, and ventilator support.

▪ PREVENTION. Preventive actions include activities to prevent spinal cord injury as shown in Figure 15-12.

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RARE DISEASES

Although some of the disorders discussed in this section are familiar to the public due to their exposure in the media and to intensive solicitations for research, they are actually rare diseases of the nervous system, considering all the various disorders that affect this system.

Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a destructive disease of the motor, or movement, neurons. The cause of ALS is unknown, although genetic and viral-immune factors have been suggested.

FIGURE 15-12 Spinal cord injuries.

   ALS is characterized by atrophy of the muscles, leading to a progressive loss of movement of the hands, arms, and legs. As the disease progresses, loss of muscle function in the face and chest area leads to difficulty talking, chewing, swallowing, and breathing. Eventually, the loss of motor function causes quadriplegia.

   One distinguishing factor of ALS is that there is not a loss of sensory neurons. The individual can feel the extremities, but movement is impaired. Mental function is unaffected, so the affected individual is aware of the condition and can take an active role in planning care. ALS usually affects men twice as often as it affects women, with onset of the disease after age 50.

   Treatment is supportive because there is no cure for ALS. Management of respiratory complications is vital because most individuals affected with ALS die of respiratory failure. ALS is eventually fatal, with death usually occurring 4 to 6 years after onset. In some cases, affected individuals have remained active for 10 to 20 years after onset.

Guillain-Barré Syndrome

Guillain-Barré syndrome is an acute, progressive disease affecting the spinal nerves. The cause of this disease is unknown, but it is suggested to be an autoimmune disorder because the symptoms usually begin 10 to 21 days after a febrile illness such as a respiratory infection or gastroenteritis.

   Early symptoms include nausea, fever, and malaise. Within 24 to 72 hours, paresthesia (PAR-es-THEE-see-ah; abnormal sensation, burning, tingling, or numbness), muscle weakness, and paralysis usually begin. These symptoms generally begin in the legs and move upward but can also start in the face and arms and move downward.

   Guillain-Barré syndrome becomes life-threatening if respiratory muscles are involved. Symptoms can progress for several days to some weeks. When progression ceases, recovery begins and can require 3 to 12 months. Treatment is supportive. Recovery is usually complete.

Huntington's Disease

Huntington's disease, also known as Huntington's chorea, is an inherited disease. It is a dominant gene disorder affecting 50% of all children in families in which one parent has Huntington's. This disorder does not appear until middle age, so children are often grown before the parent shows symptoms.

   Symptoms of Huntington's consist of a progressive degeneration of the brain, characterized by loss of muscle control and chorea, a constant, jerky, uncontrollable movement. The disease also leads to mental deterioration with symptoms of personality change, moody behavior, and loss of memory. Over a period of years, dementia (total mental incapacitation) occurs.

   There is no cure for Huntington's disease. Treatment is supportive and protective with institutionalization often necessary to provide the needed care. Genetic counseling is needed in families with this inheritance pattern.

Multiple Sclerosis

Multiple sclerosis (MS) is a disease that causes demy-elination of the nerves of the CNS. Myelin, remember, acts as an insulator around nerves, much like the insulation around an electric cord. Demyelination allows information to leak from the nerve pathway, leading to poor or absent nerve transmission.

   The cause of MS is not clear. It is thought that a genetic predisposition plays some part because it is 15 times more likely to occur in first-degree relatives of affected persons. It is also believed that the immune system and viral infection play a part.

   Symptoms caused by demyelinating lesions are muscle weakness, lack of coordination, paresthesia, speech difficulty, loss of bladder function, and visual disturbance, especially diplopia (double vision). Symptoms are varied, depending on the location of the lesions, making diagnosis difficult.

   MS usually affects young adults between the ages of 20 and 40 years. It is characterized by periods of remission and exacerbation, usually over a period of several years.

   Physical therapy and muscle relaxants can be helpful to maintain muscle tone and reduce spastic movement. The severity of the disease varies from individual to individual, but generally speaking, most affected individuals live a normal life span.

EFFECTS OF AGING ON THE SYSTEM

The effects of aging on the nervous system are some of the most noticeable to the older adult. With aging, there is a decrease in nervous system activity in the brain and spinal cord due to a loss of neurons and shrinkage of the hypothalamus. Research has shown that continued active use of the brain decreases this process to some extent, but some changes still occur. With these changes in the brain and spinal cord come many changes in the individual's functioning, for instance, a loss in short-term memory but not in long-term memory. There is also a slower general reaction time. The older person also might have difficulty completing fine motor skills. General touch perception is somewhat diminished, too, so the individual might have difficulty distinguishing temperature changes and pain stimuli.

   Vision ability is one of the first changes the individual often notices. There is a loss of visual acuity and a decrease in peripheral vision. Some individuals also become intolerant of very bright light and have difficulty adapting to changes in light from dark to bright. Some hearing loss is a subtle process that occurs at different levels in individuals. Taste sensation also can diminish over time.

   Sleep patterns are usually affected in the aging process. Generally, the older adult does not sleep as well at night but makes up for this deficit by taking short naps throughout the day or in the early evening.

SUMMARY

The nervous system is a highly complex system responsible for the individual's ability to reason, interact with other individuals, understand complex ideas, and respond both intellectually and physically. Disorders of the system usually result in symptoms involving many other systems.

   Injuries to the brain, neck, and spinal cord are a main cause of disability and death nationwide. Permanent neurologic deficits are common in brain and spinal cord injuries.

   Changes in the nervous system with aging result in some of the most commonly seen symptoms; losses in the senses are the most noticeable problems. Changes in vision and hearing are some of the earliest symptoms realized by the middle-aged individual. Alzheimer's disease is one of the most common disorders of the nervous system diagnosed today.

REVIEW QUESTIONS

Short Answer

• 1. What are the functions of the nervous system?

• 2. Which signs and symptoms are associated with common nervous system disorders?

• 3. Which diagnostic tests are most commonly used to determine the type and cause of nervous system disorders?

Matching

• 4. Match the disorders listed in the left column with the correct description in the right column:

CASE STUDIES

▪ Mr. Speed is a 57-year-old gentleman who has been recently diagnosed with Alzheimer's disease. He is in the early stage of the disease at this point. Mrs. Speed is quite concerned about the progression of the disease, whether Mr. Speed can still be employed, if he can be left alone for several hours at a time, and what medications he will be required to take. How would you respond to her concerns? Is there other information that would be helpful to the Speeds? Where can they find more information about Alzheimer's disease?

▪ Mrs. Simpson, age 56, comes to the clinic for her yearly routine physical examination. She asks you about receiving the vaccine for shingles that she heard about on television. She thought she should get it because her sister had shingles a year ago. Mrs. Simpson stated that her sister really suffered with the disease, and she does not want to have that same experience. What can you tell her about the vaccine? Is she a candidate for Zostavax®? Who should receive the vaccine? Where can she find more information about this vaccine?

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