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CHAPTER 14: NEUROLOGIC DISORDERS

Overview

Symptoms

    Dizziness

    Fainting (Syncope)

    Seizures

    Tremors

    Speaking Difficulty (Aphasia)

Conditions

    Huntington's Disease

    Parkinson's Disease

    Stroke

    Meningitis


Overview

Neurologic conditions are extremely common in elderly people and are a major source of disability. When cells of the nervous system disappear after severe injury, they are lost forever because they cannot reproduce; however, remaining nerve cells tend to compensate for lost neurons by growing new connections. This process resembles the growth of trees in a forest: If a tree is lost, the remaining trees sprout new branches to restore the canopy. Additional compensatory mechanisms are also available.

    Neurologic problems seen in older people can be grouped into three categories: cerebrovascular disorders (those caused by problems in the blood supply to the brain), degenerative disorders (when a part of the brain atrophies), and other conditions such as brain tumors or seizures. Numerous medical conditions and a huge number of medications can affect neurologic function.

    Changes in neurologic function result from diseases and cannot be ascribed to normal aging. Because of this, any new change in function must be carefully evaluated.

SYMPTOMS Dizziness

Dizziness is used to describe a variety of unpleasant sensations that often interfere with balance and walking. It is one of the most common complaints mentioned by people over age 65. People sometimes use "dizziness" to describe unpleasant faintness, light-headedness, or poor balance. Blurred vision, double vision, and changes in blood pressure may also be interpreted as dizziness. Age-related deterioration of the balance mechanisms makes any disorder of the inner ear particularly distressing to older people. Because of this variety of symptoms, a key aspect of the evaluation involves determining exactly what a person means by "dizzy." Disequilibrium, light-headedness, and vertigo (a spinning sensation) may all be reported as dizziness, but the approaches needed for evaluation and treatment usually differ. A simple classification is dizziness without spinning sensation and dizziness with spinning sensation.

Dizziness Without Spinning Sensation

Several disorders, such as disequilibrium (unsteadiness) and light-headedness, may interfere with walking, but do not cause a spinning sensation. A person may complain of poor balance or dizziness.

Causes of Dizziness Without Spinning Sensation. Disequilibrium in elderly people may be caused by deficiencies in sensory perception. Poor vision, arthritis, and foot problems may contribute to this condition of altered sensation. A previous stroke can produce sensory problems that are experienced as a balance problem or dizziness. Some people who complain of dizziness actually mean light-headedness. In this condition, the problem is rarely in the nervous system and it is almost never caused by small strokes. A few people with epilepsy may have this complaint, but the most likely causes of light-headedness are changes in blood pressure with standing (orthostatic hypotension), irregular heartbeat, near fainting, anxiety, depression, and severe narrowing of a heart valve.

Management of Dizziness Without Spinning Sensation. The management of such disequilibrium begins with avoiding medications that could be contributing to the problem. A cane can help stabilize the person's walking by adding an extra sense of the ground. Proper glasses and a hearing aid may be helpful for people with vision and hearing problems. Keeping the lights on at night helps to prevent falls by increasing sensory input. Management of heart and blood pressure problems is tailored to the specific condition.

Dizziness with Vertigo, a Spinning Sensation

Vertigo is defined as a spinning sensation, a distortion of orientation, or the erroneous perception of motion. It may be present all the time or brought on by certain positions.

Causes of Dizziness with Vertigo. Stroke and transient ischemic attacks (TIAs) involving the circulation in the base of the brain can cause sudden vertigo. A stroke or bleeding in the cerebellum can cause sudden vertigo, but this is usually associated with sudden arm or leg clumsiness or a staggering gait. This condition occurs abruptly and often the person cannot walk. Vomiting is a frequent sign of this disorder, but headache is not common.

    Disorders of the inner ear (the labyrinth) are usually the cause when vertigo is the only neurologic symptom. A prominent feature of this is a rhythmic oscillation of the eyes called nystagmus. A person with inner ear problems may have experienced similar vertiginous attacks in the past. While not life-threatening, inner ear problems can be disabling. People complain of spinning (usually away from the side of the affected ear), difficulty walking, nausea, and vomiting.

    Inflammation of the inner ear, known as neurolabyrinthitis, is characterized by the sudden onset of very severe vertigo continuing for up to 24 hours. There are no changes in hearing and no other neurologic findings. It is a benign condition that can occur as a single episode or can recur. It is thought to be caused by a viral infection of the nerves in the ear.

    Benign positional vertigo is severe vertigo that occurs with a particular head position or on turning. It can be brought on if a person tilts the head back and sometimes occurs again when sitting up. If this maneuver is repeated many times in succession, the intensity of the vertigo may decrease. While this condition generally gets better on its own, it can recur. The person can generally avoid further attacks by learning to change positions slowly. The condition is caused by abnormalities in the middle ear.

    People with problems in the cerebellum or brain stem may also have vertigo when they change positions. In such cases, vertigo begins immediately with the change of position and lasts longer than 30 to 40 seconds. It does not get better after repeated movements.

    Recurrent vertigo with progressive hearing loss is called Ménière's disease (after the 19th-century French scientist, Prosper Ménière, who first described vertigo related to the inner ear). It is characterized by episodes of severe vertigo, nausea, and vomiting that may last for a week or more and may be disabling. Between episodes are often mild dizziness and ringing in the ears. The disorder worsens, eventually leaving the older person deaf and in some cases with impaired balance and gait. An interesting phenomenon early in the course of the illness is that people traveling in an airplane often describe improvement in their symptoms, possibly due to the decrease in atmospheric pressure.

Management of Vertigo. Older people with sudden vertigo may require hospitalization to prevent dehydration due to vomiting. Treatment generally consists of rest and mild sedation. People usually tolerate positional vertigo without medicines once they have learned to adapt their movements.

Fainting (Syncope)

The medical term for loss of consciousness, or fainting, is syncope (pronounced SIN-co-pee, from the Greek meaning "to cut off"). Syncope involves a transient loss of consciousness accompanied by unresponsiveness and loss of muscle tone followed by a spontaneous recovery. It occurs in response to a sudden loss of blood flow to the brain; it is not considered a disease in itself, but rather a symptom of one or more possibly serious conditions.

    Syncope occurs in about 2 percent of people between the ages of 65 and 69. It increases to about 12 percent in those over age 85. About 6 percent of people in institutions have syncope and about one-third of these people have multiple attacks. The death rate for people who have syncope is about 1½ times that for people who do not have syncope. This is probably due to the underlying disease itself rather than the loss of consciousness.

    People over the age of 65 who have experienced loss of consciousness due to heart disease have a 33 percent risk of death after one year. This death rate is compared to the 6 to 12 percent rate for those who experience loss of consciousness due to other causes. For those people with no clear cause of syncope, the death rate is about 6 percent. Syncope does not produce a significant increase in death rate for older people in nursing homes, but it is an important risk factor for accidents, such as falls.

Causes of Syncope

Loss of consciousness may be due to normal cardiovascular aging (as described below) or to underlying diseases or medications that can interfere with normal blood pressure control. Generally, when we stand up, between one and two pints of blood become temporarily pooled in our legs. In younger people this reduction in circulating blood volume is detected by receptors in the lungs and large blood vessels in the neck. These receptors alert the nervous system, which, in response, signals the blood vessels in the legs to contract, and the heart to beat faster. This protects the person from having any large drop in blood pressure. With aging, there is a progressive decrease in the heart's ability to beat faster after a change of position, a period of exercise, a loss of blood volume, or in response to other stimuli. Consequently, the heart does not always respond promptly or adequately to signals from the nervous system telling it to beat faster in response to reduced blood volume and, ultimately, our blood pressure drops. This age-related decline in maximum heart rate leaves us vulnerable to a drop in blood pressure and possible syncope.

    The kidney's decreasing ability to retain sodium coupled with a blunted thirst response to dehydration predispose us to dehydration and a drop in blood pressure as we age. An additional factor is that the aging heart does not relax quite as effectively between beats. Because of this, our heart must have as much blood returned to it as possible to maintain a normal blood pressure. Therefore, we become increasingly vulnerable to a drop in blood pressure if our blood volume is reduced or if medications cause our blood vessels to dilate.

    Blood flow to the brain is also reduced with aging and if relatively common diseases like congestive heart failure or blood vessel disease to the brain (carotid artery disease) are superimposed, this can cause a further reduction in blood flow. These conditions can bring the blood flow to the brain close to the critical threshold required to maintain consciousness. Because of this increased vulnerability, relatively mild disturbances such as rapid breathing or mild dehydration can lead to a drop in the blood flow to the brain and produce syncope. Furthermore, since high blood pressure may have conditioned the blood vessels in the brain to adjust to a higher level of blood pressure, older people with high blood pressure may require this increase in pressure to maintain adequate levels of blood flow to the brain.

    The causes of syncope, as shown in Table 15, can be classified as orthostatic hypotension (low blood pressure syndromes), abnormalities in the composition of the blood, heart disease, and primary brain disorders.

Orthostatic Hypotension. A drop in the blood pressure with changing position from lying to standing is called orthostatic hypotension. This is a common cause of syncope. Estimates of how common orthostatic hypotension is vary widely, but probably around 5 percent of older people with normal blood pressure have significant orthostatic hypotension. For people with high blood pressure, this prevalence may increase to 20 to 30 percent. The strictest definition of orthostatic hypotension is a drop in the blood pressure of 20 millimeters of mercury or more, with standing, and is associated with symptoms such as light-headedness, dizziness, or unsteadiness. Orthostatic hypotension suggests an underlying inability to maintain blood pressure that predisposes the person to a further blood pressure reduction as a result of dehydration, blood loss, or medications.

Table 15. Causes of Fainting (Syncope)

ABNORMAL BLOOD COMPOSITION
BRAIN DISORDERS
      Blood vessel disease Seizures
HEART AND CIRCULATORY DISEASES
      Heart attack Pulmonary embolism
      Heart rhythm problems Heart valve problems
ORTHOSTATIC HYPOTENSION (LOW BLOOD PRESSURE)
      Blood vessel dilation Volume depletion
      Drugs

    There are several causes of orthostatic hypotension. The adverse effects of medications are the most common cause of orthostatic hypotension in older people. Drugs used to treat depression or high blood pressure are common offenders. Sometimes the blood pressure will drop immediately after eating and this may be further worsened by taking blood pressure medications just before meals. Prolonged bed rest can also result in a drop in blood pressure when a person rises from bed to a standing position. This is probably caused by deconditioning of the cardiovascular system.

    Orthostatic hypotension can also result from disease states of the nervous system. The symptoms that suggest such diseases include dizziness on standing, visual problems, urinary incontinence, an inability to sweat, difficulty tolerating the heat, constipation, chronic fatigue, and impotence. Parkinson's disease, multiple strokes, and other vascular problems are common central nervous system disorders that are associated with orthostatic hypotension and problems maintaining the blood pressure. (See Table 16 for approaches to managing orthostatic hypotension.)

Other Causes of Syncope. In some cases syncope can be explained by increased sensitivity of pressure sensors in the neck, which can be further aggravated by tight collars, neck turning, and various drugs.

    In people who have other risk factors, urinating, passing a bowel movement, and coughing can produce loss of consciousness. This syncope occurs as a result of the combined effects of impaired return of blood flow to the heart, nervous system reflexes, and of age-related changes in the ability of the heart to speed up and to constrict the blood vessels in the legs. Syncope after a meal may represent a drop in blood pressure due to blood pooling in the abdomen.

Table 16. Management of Orthostatic Hypotension

NONPHARMACOLOGIC INTERVENTIONS
      Substitution or discontinuation of offending medications
      While recumbent, exercising the legs and feet prior to standing
      Wearing full-length elastic stockings
      Maintaining a high-salt diet (in absence of fluid overload or heart failure)
      Elevating the head of the bed 5 to 20 degrees

    Severe narrowing of one of the heart valves, called aortic stenosis, is the most common change in the structure in the heart. In this condition, fainting during physical activity depends on how tight the narrowing is. In older people, loss of consciousness is sometimes the sole symptom of a heart attack, representing injuryrelated reductions in the ability of the heart to pump blood. Irregular heart rhythms can also produce loss of consciousness by reducing blood flow to the brain. It is rare for syncope to occur as the result of a primary problem in the brain such as a stroke or epilepsy; but when it does, there are usually other severe neurologic changes. Seizures, however, may accompany syncope regardless of its cause.

How Syncope Is Evaluated

Even after an extensive evaluation, the cause of syncope is not always clear. About one-third of people evaluated have a specific disease-related cause such as heart disease; another third have low blood pressure caused by orthostatic hypotension, eating, or medications; and in the last third no clear cause is ever discovered. The evaluation includes documentation of factors that led up to the loss of consciousness, the time it began, how long it lasted, and how the person recovered. Knowing about additional symptoms can also be helpful. Any prescriptions or over-the-counter medications must be evaluated.

    A physical examination includes measuring blood pressure while the person is in different positions, including lying, sitting, and standing. The intensity, rhythm, and quality of the pulse measured in the neck, arms, and legs are evaluated. The person is further examined for signs of heart disease, gastrointestinal bleeding, decreased blood volume, and diseases of the nervous system. People aged 70 or older often have syncope in association with an irregular heartbeat. A common procedure is to check for this condition with an electrocardiogram monitor that can record heartbeats for 24 hours while the person carries on normal activities, and in particular the activities performed at the time of loss of consciousness. On the other hand, since so many people aged 75 and older have irregularities in their heartbeat rhythm, arrhythmia by itself, when there is no loss of consciousness, is not necessarily a dangerous symptom.

Management of Syncope

It may be possible to treat older people for a specific cause of syncope, but, more often, multiple potential causes may need to be treated. An important decision is whether to discontinue or change the doses of medications potentially causing low blood pressure. A person using medication for high blood pressure may need to adjust the dosing schedule, particularly at mealtimes, because some older people develop low blood pressure after eating.

Seizures

A seizure may occur as a single event that is produced by a specific problem and that recurs over time with varying frequency. This recurring type of single seizures is called epilepsy. Seizures can also be continuous, consisting of sequences of fits separated by minutes or seconds--a condition called status epilepticus. In about 90 percent of elderly people with the new onset of seizures, there is an identifiable brain problem.

Types of Seizures

The various types of seizures are classified and defined according to their characteristics as noted by a physician and the results of an electroencephalogram (EEG) test (sometimes called a brain wave test). Generalized seizures cause the person to lose consciousness while convulsive movement occurs on both sides of the body. Generalized major seizures, called grand mal seizures, are the ones most commonly seen in elderly people. Petit mal seizures are also encountered in adults. These cause a momentary loss of awareness without any major movement. The person stares off into space for a few seconds and then returns to consciousness (sometimes completing the sentence started just prior to the onset of the seizure). Focal or partial seizures are ones that emanate from a particular part of the brain and are manifested by a sudden change in movement, sensation, or behavior. The person usually remains conscious during this sort of seizure. In one variation, called complex partial seizures, there can be an alteration in consciousness. Complex partial seizures arise from an abnormality in the temporal lobe of the brain, the part of the brain just above the ear. The temporal lobe seizure syndrome varies but it often involves psychiatric phenomena such as hallucinations, illusions, panic states, and bizarre activity of the arms and legs. Partial seizures can also develop into generalized seizures.

Causes of Seizures

About half of the seizures that older people experience for the first time are caused by strokes that occurred earlier in the person's life. These strokes are usually small and may have been forgotten or never clinically identified. In another 12 percent of people, seizures occur at the onset of an acute (sudden) stroke caused by a blood clot that has traveled into the brain, called an embolus. Seizures can also occur during the rehabilitation phase in about 15 percent of individuals suffering from an acute stroke. About 10 percent of people who have had a stroke suffer a recurring seizure disorder that requires treatment with medications. Bleeding within the brain and hemorrhages in the brain lining frequently cause seizures during the acute phase of the event.

    Seizures that are caused by any structural problem within the brain may be provoked by an underlying infectious illness or a change in body chemistry. Focal seizures in elderly people can be caused by brain tumors, brain abscesses, and previous head trauma. People who have meningitis or encephalitis can also have generalized seizures. About 25 percent of people in the late stages of Alzheimer's disease can have generalized seizures. Multiple strokes that cause dementia may also produce seizures.

    The temporary neurologic dysfunction that occurs after a focal seizure can sometimes be confused with that of a transient ischemic attack (TIA). (TIAs are discussed later in this chapter.) They represent a transient disability that completely resolves in a few minutes to hours. Focal sensory seizures can cause temporary numbness or other subjective feelings of abnormality, for example, vision shifts, funny smells, or strange sounds. A person may also move differently, whether or not he or she experiences the sensory phenomena. Intermittent rhythmic moving of a hand or foot, facial twitching, or other jerky movements are all possible indications of an underlying seizure. When the focal movement problem spreads, the person loses consciousness and develops a generalized seizure. If the focus of the seizure is in the part of the brain that controls movement, the person may, at the cessation of the seizure, develop mild paralysis (called Todd's paralysis, for the American neurologist Eli Todd) that usually disappears within a few hours. Sometimes the Todd's paralysis can last a day or so and create the misleading impression that the person has had a stroke. Fortunately, in most instances the paralysis disappears with no aftereffects.

The Evaluation of Seizures

Because seizures can be associated with so many different disorders, the physician's evaluation is comprehensive. A complete medical and neurologic examination can sometimes show sudden illnesses that precipitated the seizure. A spinal tap may be necessary if the physician suspects meningitis because of the presence of fever, changes in mental function, or a severe or persistent headache. Brain imaging, such as a CT scan or an MRI scan, is usually suggested to identify abnormalities in the brain such as tumors, abscesses, or blood clots. The MRI is usually better than a CT in identifying these abnormalities.

    The electroencephalogram (EEG) can sometimes be helpful in identifying the focal point of the seizure activity. An EEG is not needed to detect that a person is having or has had a grand mal seizure--these seizures speak for themselves. However, in more subtle seizures the EEG can help to identify the abnormal brain waves that explain the person's behavior while the seizure is taking place. Elderly people with recurrent seizures can have abnormal EEG tracings that reflect an abnormality in the brain structure. However, people who have had a single seizure due to effects of medication or a change in body chemistry may have a normal EEG after the seizure. The amount of abnormality on the EEG does not tell much about the severity of the underlying cause.

Treatment for Seizures

The first step in the management of a person with recurrent seizures is to correct any underlying process that might be provoking the seizures. A brain abnormality that might be the cause of seizure might also be impossible to remove, but it still may be possible to improve the person's state of health. Common problems of body chemistry that can induce or aggravate seizures include having a low level of sodium in the blood, a low calcium level, low blood sugar, and alcohol toxicity.

    Drug treatment is usually the next step in management. The choice of a particular drug is less important than its correct use. It may take a while for a medication to stop the seizures, and dosages should be changed only after appropriate blood levels of the medication have been maintained at a steady state and have failed to stop the seizures. In older people, side effects can occur at much lower doses than they do in younger people. For example, some medications used to control seizures may diminish cognitive function in older people and in some individuals doses can impair memory and cause changes in behavior. Because of this, the medication initially chosen should be given in an adequate dose for a period long enough for the drug to reach its steady state in the blood before it is replaced by another medication or another medication added to the regimen. If possible, the medication should be taken in once-a-day dosages in order to simplify the routine. Such once-a-day dosing should be adhered to if it is at all possible.

    Recurring seizures that are caused by problems in the brain, such as strokes or brain tumors, are more difficult to control than those seizures that occur in the late stage of Alzheimer's disease. The person with Alzheimer's disease may have a single seizure as the result of some other illness; there is no need to treat such a seizure unless it recurs. People with Alzheimer's disease have an increased chance of developing a hemorrhage and subsequent blood clot in the space between the brain and the skull, a condition called a subdural hematoma. This condition may cause and thus reveal itself through a seizure.

Tremors

A tremor is medically defined as the involuntary vibrating movement across a joint caused by muscle contractions. Tremors are generally described in terms of how rapid they are, how much shaking appears, and whether the tremor occurs without movement at rest or whether it occurs with action. All tremors get worse with emotional stimulation, and they all disappear with sleeping.

Types of Tremors

Tremors are classified as either resting tremors or action tremors. In "resting" tremors, the shaking worsens when the body rests and actually goes away with movement. In contrast, with the "action" tremor, no tremor is evident at rest, but it appears when the body part is moved and often gets much worse as the body part moves away from the body. Resting tremors are caused by Parkinson's disease, which produces dysfunction of deep structures in the brain called basal ganglia. Action tremors are often seen in diseases of the cerebellum, the back portion of the brain that helps coordinate movement.

    Normal, healthy people have a very rapid fine-action tremor--called physiologic tremor--that can easily be observed by placing a piece of typing paper on one's outstretched fingers. The edge of the paper exhibits a very fine movement indicative of this normal vibration. This normal tremor may become more evident in states of anxiety, exercise, sleep deprivation, or by stimulant drugs so that it can be seen clinically. This is the tremor of nervousness or stage fright.

    An action tremor that originates in the central nervous system, called essential tremor, is a tremor that is somewhat slower and more pronounced than the physiologic tremor and is more evident on action. Usually this tremor affects the arms more than the legs, and it sometimes produces head bobbing. There is often a family history of a similar tremor.

Treatment of Tremors

Mild sedation may help the person with an essential tremor. Initially, alcohol diminishes the tremor, but once alcohol has been metabolized, the tremor may become worse. The prescription drug propranolol is sometimes used to reduce the amount of vibration produced by the essential tremor.

Speaking Difficulty (Aphasia)

The difficulty in speaking, called aphasia, involves a diminished language capacity produced by a specific problem in the brain. Aphasia is different from mutism, which is a state where no sounds are produced. It is also to be distinguished from dysarthria, which is a disturbance that reflects the loss of control over the voice box and other parts of the speech production apparatus. Dysarthria is characterized by slurring words, imprecise articulation, and a distortion of sounds.

Types of Aphasia

Aphasias are generally classified according to the person's fluency of speech, comprehension of spoken language, and ability to repeat words and phrases. This classification also helps the examiner to deduce the site within the brain of the problem causing the abnormality. Since most aphasias include naming problems, difficulty with this task is a useful way of identifying an aphasic disturbance from other speech problems. On the other hand, it is not helpful in telling the type of aphasia since it is common to all types. Writing abnormalities almost always mirror the characteristics of the person's spoken voice, but reading aloud and reading comprehension are affected differently in various types of aphasia and are usually evaluated separately.

    The characteristics of spontaneous, verbal output help determine whether the aphasia is fluent or nonfluent. Nonfluent aphasias are characterized by a relative lack of speech, effortful speech production, problems with pronunciation, decreased phrase length, and problems with grammar, but what the person says conveys useful information. In addition, there are few paraphasic errors. Paraphasic errors may be literal, where sounds or homonyms are substituted, or they may be verbal, where one word is substituted for another, or they may be nonsense words. The fluent aphasias are characterized by normal-sounding speech or even an increased amount of speech. The speech production seems to require little effort and the phrase lengths sound normal. Other characteristics include normal speech melody and inflection, but the content is empty with very little information, and there are a number of paraphasic errors. Fluent aphasias may also be associated with difficulties doing calculations, telling right from left, identifying fingers, and problems in establishing the order of various tasks.

Causes of Aphasias

Aphasia may occur with any disorder that involves the left side of the brain (in the area near the left ear) in people who are right-handed and for most people who are left-handed. Aphasia is observed in people who have had strokes, brain tumors, trauma, and in dementing disorders such as Alzheimer's disease and Pick's disease. The nonfluent aphasias usually result from carotid or middle cerebral artery disease, while fluent aphasia usually results from emboli, blood clots that travel to the brain and obstruct an artery.

Evaluation of Aphasias

An evaluation of a person with aphasia generally involves testing spontaneous speech, comprehension, repetition, naming, reading, and writing. Comprehension is often assessed by asking people to follow simple instructions such as to point to objects in a room and to answer yes or no questions. Attention is tested by asking the person to repeat words, phrases, and increasingly long sentences. The ability to name objects is evaluated by pointing to various objects in a room, body parts, or items of clothing. Reading is usually assessed by having the person read aloud and follow written commands. Writing is evaluated by having the person write words, phrases, and sentences.

Treatment of Aphasias

Management first involves identifying the cause and then specifying the treatment. Partial recovery from aphasia is the rule. Speech and language therapy produce improvement in function. Aphasias involving the least loss of speech functioning are generally associated with the best long-term improvement.

CONDITIONS Huntington's Disease

Huntington's disease (named after the American doctor, George Huntington, who described it) is an inherited dementing illness. This disease affects the nervous system and is characterized by abnormal movements and psychiatric symptoms. Virtually all of the cases of this disease in the U.S.A. have been traced back to six individuals who emigrated from England in 1632. The illness usually begins when the person is between 30 and 40, but it may occur before the age of 15. About a quarter of cases occur after 50. It affects between 3 and 7 people per 100,000 people in the population at large.

Cause of Huntington's Disease

Atrophy in two deep brain structures called the caudate and putamen are characteristic of the disease. The genetic defect for Huntington's disease is on the short arm of chromosome 4.

Symptoms of Huntington's Disease

Mental difficulties may precede or follow the movement disorder in Huntington's disease. The movement disorder is characterized by writhing, jerky movements; it usually begins in the hands and face and eventually involves the limbs, neck, and trunk; abnormal movements of the eyes are frequently seen. Individuals may become depressed or irritable, aggressive, and impulsive; occasionally, a major psychiatric illness may develop. As the disease progresses, thought processes slow, impairment of insight and judgment occurs, and people display an inability to maintain a set of activities or to organize their thoughts. There may be impaired memory, especially for skilled activities.

Treatment of Huntington's Disease

Currently Huntington's disease has no satisfactory treatment. However, genetic research holds considerable promise for a cure at some point in the future.

Parkinson's Disease

Parkinson's disease (named for the English physician who first described it in 1817, James Parkinson) is the second most common degenerative disease of the nervous system--the most common is Alzheimer's disease. Parkinson's disease is a slowly progressive disease of the nervous system that is associated with an average survival of about 14 years, although people can live considerably longer. It is fairly common in people between 60 and 65 years of age and is most common among those aged 75 and older.

Causes of Parkinson's Disease

In Parkinson's disease, there is a loss of the nerve cells in the brain that contain a dark pigment. These pigmented cells normally produce a substance called dopamine, which acts as a chemical messenger between nerve cells. Dopamine production is markedly reduced in the parts of the brain that contain these pigmented neurons. No one knows why these neurons are lost in Parkinson's disease.

    Long-term exposure to the metal manganese can cause a syndrome that resembles Parkinson's disease, but in most cases it has not been possible to relate the disease to a specific environmental toxin. Research on possible environmental factors continues.

Symptoms of Parkinson's Disease

The principal feature of Parkinson's disease is slowing of movement (bradykinesia). This slowing occurs not only in the initiation of movement but also in a reduction in speed during the course of movement. This slowness starts on one side of the body and usually ends up involving both sides. The slowness progresses from the hands toward the body. Very early in the condition, the arm fails to swing normally when the person is walking. Late in the disease there is almost no movement in the body at all. The slowness of a single arm or leg in early Parkinson's disease can be confused with paralysis, but a person with Parkinson's disease has normal power of movement if given enough time. In addition to this slowed movement, people with Parkinson's disease have stiffness in the muscles so that if the arm or leg is moved passively by another person, there is a fluid resistance to movement. To the examiner, the arm feels like it is being moved through a sea of cold molasses.

    Most people with Parkinson's disease have a distinctive coarse tremor at rest. The tremor begins at the fingers with a pill-rolling movement and over time begins to involve the hands and then the arms. The combination of the resting tremor, the muscle stiffness, and the lack of movement represents the hallmark of Parkinson's disease. The lack of movement interferes with walking, producing the characteristic bent-over shuffling gait. Generally, people are not prone to falling early in the course of the disease, but as it progresses they develop an increasingly unstable gait. Another feature is softening of the voice so that late in the course of the illness, the person speaks in a whisper. Fine movements of the hands, such as buttoning shirts or tying shoelaces, may be impaired. Some people notice that their handwriting gets smaller and smaller as the disease progresses.

    Depression and dementing illness are other important components of Parkinson's disease. As many as 40 percent of Parkinson's victims have some type of depression, which may be due to changes in the chemical breakdown of certain brain substances and not simply due to despair over the loss of function.

    Constipation is another common symptom of Parkinson's disease. Contributing factors include decreased physical activity, disease-related changes in bowel function, and the effect of drugs. Treatment for this usually involves forcing fluids, modifying the diet, and using laxatives. Another common feature is drooling, caused by the person's infrequent swallowing and posture, which is usually bent forward. People can lose weight during their illness, and this weight loss is not always due to a decrease in appetite. Excessive oily dandruff on the scalp and eyebrows and dry eyes and dry skin are other complaints.

Treatment of Parkinson's Disease

The management of Parkinson's disease requires careful cooperation with the primary physician. The mainstay of treatment is levodopa (L-dopa), which the body converts to the missing substance, dopamine. L-dopa is usually combined with another medicine called carbidopa, which keeps this conversion from happening outside of the brain, allowing more of the L-dopa to be delivered to the brain. Elderly people are often started on 25 milligrams of carbidopa and 100 milligrams of L-dopa administered twice a day. The dose is gradually increased until symptoms decrease or side effects appear. Usually a total daily dose of 75 to 100 milligrams of carbidopa is necessary to reduce the side effects of L-dopa: nausea, diarrhea, low blood pressure, and irregular heartbeat.

    However, the most significant adverse reactions to these medications in elderly people are the precipitation of sudden psychosis and hallucinations. People who are taking L-dopa can also develop other movement problems such as writhing of the arms or neck, which they seem to tolerate better than the slowness or cessation of movement. Another medication, called selegiline, helps to increase the effects of L-dopa and lengthen its action. This medication is a weak antidepressant; the antidepressant effects may contribute to its effectiveness. In addition, several studies suggest that selegiline may actually help prevent loss of nerve cells.

    Amantadine, a drug used for influenza, has been helpful in some people. It is not clear exactly how it works, but it seems to influence the release of dopamine. Amantadine is usually given with L-dopa, but it is common for the beneficial effects to wear out after a few months. Sometimes hallucinations and delirium occur as side effects to amantadine.

    Occasionally, bromocriptine, a dopamine stimulant, is added to the L-dopa and carbidopa regimen. Bromocriptine is particularly apt to cause psychosis in elderly people, so the initial dosage is usually extremely low. Pergolide is another dopamine stimulant that is associated with the same adverse effects as bromocriptine.

    When used alone, drugs that block acetylcholine, a different chemical messenger, or neurotransmitter, may reduce the symptoms of Parkinson's disease. These drugs can also be added to a regimen if L-dopa and carbidopa fail to relieve the person's symptoms adequately. The side effects associated with these drugs include dry mouth, constipation, difficulty voiding, lethargy, and psychosis or delirium.

Disorders Similar to Parkinson's Disease

While a number of disorders produce a condition that resembles Parkinson's disease, telltale differences can help distinguish them. Progressive supranuclear palsy is a degenerative disorder that causes slow movements and sometimes a tremor; however, this disease usually progresses much more rapidly than Parkinson's. A person with progressive supranuclear palsy falls early in the course of the disease and experiences difficulty with the tongue, mouth, and other muscles around the face. Difficulty speaking and swallowing are early findings. In addition, stiffness usually occurs in the body and then spreads to the arms and legs, rather than starting in the arms and legs and spreading to the body as in Parkinson's disease. However, the most distinctive feature of progressive supranuclear palsy is the onset of difficulty in moving the eyes up and down and later from side to side. While people with Parkinson's disease may have some mild limitations of eye movements, they experience this to a much lesser degree.

    An illness called Shy-Drager syndrome causes a combination of slow movements, significant nervous system dysfunction, clumsiness, and additional findings that are not seen in Parkinson's disease. Another way to differentiate these conditions is that neither Shy-Drager syndrome nor progressive supranuclear palsy responds to L-dopa.

    Although people who have many small strokes appear to be slow moving, a physician can usually tell that they are only slow to begin movement but not slow to execute the movement. They generally do not have tremors and show signs of increased muscle tone (spasticity) rather than stiffness (rigidity).

Movement Problems Caused by Drugs

The drugs used to treat psychiatric diseases (antipsychotic drugs) often interfere with dopamine release and are among the major causes of movement disorders in elderly people. The factors that determine the severity of the movement problem are the dosage of the drug, the length of time the person has been on it, being older, and being female.

    Parkinsonism (conditions that look like but are not Parkinson's disease) is an expected effect of the long-term use of antipsychotic drugs. Some people with drug-induced parkinsonism do not have the muscle stiffness that is seen with Parkinson's disease. The manifestations of drug-induced parkinsonism usually disappear when the drugs are stopped, but years of high-dose therapy may produce parkinsonism that does not disappear.

    Tardive dyskinesias are movement disorders that develop after months or years of taking antipsychotic drugs. These movements consist of rapid irregular muscle contractions that cause the person's lips, tongue, face, and neck to move constantly and purposelessly. Tongue movement can be especially evident and can protrude from the mouth in a "fly-catching" motion. The lips can smack and form many odd facial expressions.

    Sometimes long-term antipsychotic drug treatment causes extreme restlessness and an inability to remain still. Antipsychotic drugs can also cause sudden muscle reactions in any part of the body. The person usually complains of cramps and other pains as well as severe stiffness.

    Usually, these reactions are transient in nature, but they can be relieved immediately with specific medications. Movement disorders--tardive dyskinesia--that are a much-delayed reaction to long-term antipsychotic drug therapy become initially worse when the antipsychotic drug is stopped. However, they diminish within a month or so. The abnormal movements also decrease when the dose of these drugs is increased but they usually reappear shortly. People with this condition seldom complain of the mouth and tongue movements, although they are quite disfiguring. In managing tardive dyskinesia, the older person and the physician together have to weigh the benefits and risks of the antipsychotic medicine. Clearly, using the lowest effective dose for the shortest period of time reduces the chance of precipitating a tardive movement disorder.

Stroke

A stroke is an injury to brain tissue that occurs when the blood supply to the brain is inadequate due to disease or obstruction of arteries in the head and neck. The part of the brain involved is unable to transmit signals to other parts of the nervous system, thus affecting any number of body functions (see Figure 12).

    Over the past 40 years, the incidence of stroke has declined in people who are younger than 70. The reasons for the decline are not completely understood, but more aggressive treatment of high blood pressure may be a factor. However, the risk of stroke remains 12 times greater for people in their late seventies compared with the risk for those in their late fifties.

Causes of Strokes

Three mechanisms can produce a stroke: (1) a clot can form within a large or small artery supplying blood to the brain, a condition called thrombosis; (2) a clot can travel from the heart or neck up into the brain where it obstructs an artery--this is an embolus; (3) an artery can burst and hemorrhage inside the brain. Determining which of these three causes has produced a stroke is often difficult and can elude even the most sophisticated clinical examination. Generally speaking, about 35 percent of strokes are hemorrhages, 15 percent are due to emboli, and the rest are thought to be due to thrombosis.

Large-Artery Strokes

A stroke due to an obstruction or narrowing of a large artery is often preceded by a period of reduced blood supply to the brain.

Cause of Large-Artery Strokes. Hardening of the arteries, called atherosclerosis, is the most common cause of carotid artery narrowing, but a tear in an arterial wall, a constricting tumor, or other diseases involving the arteries must be considered.

Symptoms of Large-Artery Strokes. Reduced blood flow in a large artery is manifested by changes in function and sensation in the hands and face and usually lasts less than 15 minutes. If the left side of the brain is affected, then sudden difficulty in speaking can occur. This transition disability that completely resolves in minutes to hours is called a transient ischemic attack (TIA). About 50 to 75 percent of the time, a stroke due to obstruction of the main artery supplying blood to the brain (the carotid artery, which runs up the neck) is preceded by one or more transient ischemic attacks. However, among all stroke types, a preceding TIA occurs only about 10 percent of the time. The TIA may be followed by a sudden deficit in a person's ability to function normally or fluctuating deficits that develop over a period of 12 to 48 hours. About 20 percent of the time, a stroke occurs suddenly without any warning or fluctuation. The carotid artery is the site of the clot in about 5 to 6 percent of all strokes caused by decreased blood flow to the brain. After the initial stroke, there is an 8 percent chance that a second stroke will occur within the first month.

    If the blood clot affects blood circulation in the back of the head (in the region of the basilar artery), the progression of symptoms goes from dizziness to headache and finally to coma. Depending on the severity of the stroke, people may have difficulty speaking, numbness on one half of the body, double vision, weakness of the face, and weakness on both sides of the body. These manifestations may be temporary, or they may fluctuate. If they become worse, the person may not survive.

    The number or severity of TIAs does not reliably predict the severity of a potential stroke. Nonetheless, a TIA must be taken as a signal for a possible stroke, and the person who has had a TIA should be thoroughly evaluated to determine the source of the problem.

Evaluation of Strokes

Physicians have many tests available to look for narrowings or plaques in the carotid artery, and the choice of the appropriate procedures must be individualized. A conventional angiogram--injecting radiographic dye into a blood vessel and then taking X rays--remains the definitive method for evaluating vascular changes and for examining the rest of the circulation within the brain. This is often a necessary procedure for people who are considering surgical options. The risk associated with angiography is directly related to the person's overall condition and to the experience of the radiologist performing the procedure. Frequent evaluations are necessary for people whose neurological findings keep changing in order to determine the direction of change. For people who have thrombotic strokes (due to blood clots without TIAs), a functional problem that gets better and then worse usually signifies that the functional problem will become permanent and irreversible. However, the fact that the stroke has a gradual progression sometimes allows for treatment before a person has permanently lost the capacity to function.

Treatment of Strokes

Surgery to remove a plaque or to open a narrowed artery is an option for healthy people who have many symptoms related to the tight arterial narrowing of at least 70 percent or more. The use of blood thinners, called anticoagulants (heparin and coumadin), is another option to prevent strokes in people with recurrent TIAs or symptomatic carotid artery narrowing. These drugs are generally used for several months. Treatment does not appear to be necessary for people known to have carotid artery disease but who have no symptoms.

    Aspirin and other drugs that affect blood platelets also seem to help prevent TIAs and subsequent strokes. Aspirin reduces the risk of stroke due to carotid artery disease from approximately 19 to 12 percent over a three-year period. Though the recommended dose of aspirin varies, one regular aspirin (300 mg) a day seems sufficient.

    In a stroke, the aim of the initial therapy is to prevent or reduce the extent of injury to brain tissues. If it is clear that bleeding is not present (usually determined by a brain imaging study such as a computed tomography or CT scan) anticoagulation with heparin is sometimes started. Large strokes sometimes cause fluid retention, and consequent swelling in the brain can occur during the first 36 hours. Lethargy, coma, and sometimes death follow this rise in increased pressure caused by the swelling within the head. With such large strokes, it is likely that the person will not be able to function independently.

    After a stroke has occurred, careful physical and neurologic examination supplemented by special X ray procedures, such as a CT scan or MRI, can identify the location of the stroke and the arteries involved.

Small Blood Vessel Strokes

The tiny end-branches of the large blood arteries penetrate deep within the brain to serve the basal ganglia, the thalamus, the white matter below the cortex, and the brain stem. Blood clots in these small vessels (thrombosis) can cause small areas of damaged brain tissue called lacunae. In most cases, long-standing high blood pressure is responsible for this condition. Lacunar strokes, which become worse in a matter of hours, often have a fluctuating course. About 25 percent of the time, people have a history of TIAs. The TIAs of these small blood vessels cannot be reliably distinguished from those from large blood vessels without special studies. However, strokes caused by these small vessels usually have a distinctive pattern. About 60 percent of persons suffering lacunar strokes will have weakness or paralysis on one side of the body without any changes in body sensation. Other characteristic symptoms include changes only in sensation, hand function, speaking, coordination, or weakness. About 2 percent of those who have had a lacunar stroke will have a recurring stroke within a month. Over time, many of these small strokes can result in a decline in thinking ability, a condition called multi-infarct dementia (infarct means damaged tissue). Controlling high blood pressure can prevent these strokes.

Strokes Caused by Embolism

Embolism of a blood clot to the brain accounts for about 25 to 30 percent of strokes. The extent of the neurologic damage depends upon the size of the clot. If the clot is small, the damage is localized to the end-branch areas of the vascular territory. Clots can break off from a larger clot in the heart, a clot on the valves of the heart, or from large arteries such as the carotid artery. In some people, emboli are documented without a clear source of the clot. An irregular heartbeat, called atrial fibrillation, is associated with a 14 percent risk of embolism when the rhythm first starts. The risk remains about 5 percent per year afterwards. About 2 percent of people older than 60 have this condition.

Symptoms of Strokes Caused by Embolism. The onset of strokes caused by embolism is very sudden in 90 percent of cases, resulting in maximal functional difficulties in only a few minutes. A fluctuating course of functional capacity or intermittent changes in function are rarely seen in this type of stroke. A person's medical history and examination will help a physician identify the source of the original clot.

Treatment of Strokes Caused by Embolism. The high rate of early recurrence after an embolus (over 10 percent the first two weeks) forces most physicians to prescribe anticoagulants (blood thinners) unless there is a very strong reason not to or unless the stroke is very large. Mild anticoagulation seems to be effective in preventing strokes in people who have atrial fibrillation. Use of anticoagulant medications requires individual therapy to balance the benefits and risks.

Strokes Due to Bleeding in the Brain

Brain hemorrhages occur less often than other types of strokes and are often seen with high blood pressure.

Cause of Strokes Due to Bleeding in the Brain. A change in the walls of the blood vessels is a predisposing factor in brain hemorrhage in some older people. A silklike substance called amyloid makes the vessel wall more fragile.

Symptoms of Strokes Due to Bleeding in the Brain. The symptoms of people with brain hemorrhage are so similar to those of persons who have had strokes due to blood clots that the distinction between the two kinds of strokes cannot be made without special brain imaging (with CT scan or MRI) to identify the hemorrhage.

    Decreased alertness and vomiting are signs that a brain hemorrhage is occurring. Hemorrhage in the brain stem can cause coma. Bleeding into the cerebellum is a neurologic emergency, because the resulting blood can cause brain stem compression and death. Symptoms of this hemorrhage include severe headache, dizziness, clumsiness, difficulty moving the eyes, and paralysis of parts of the face. Removal of the blood clot can result in recovery if it is done before the brain stem is compressed.

Treatment of Strokes Due to Bleeding in the Brain. Except when the cerebellum is involved, treatment of brain hemorrhage is aimed at preventing the aspiration of stomach contents into the lungs, keeping the person from becoming dehydrated, and managing the underlying medical problems.

    In strokes due to hemorrhage, the outlook is determined by the size and location of the bleeding. Generally when hemorrhaging produces a blood clot larger than 5 centimeters--about the size of an egg--the outlook is very poor.

Stroke Rehabilitation

The death rate within 30 days after a stroke is between 20 and 30 percent. In any type of stroke, the outlook depends upon the size and location. Stupor, coma, severe weakness, and difficulty moving the eyes indicate large strokes and therefore predict an unfavorable outcome. The person's functioning before the stroke is also a critical factor in determining her ultimate independence. Age by itself does not limit the potential for a good outcome, but it is a factor that contributes to a higher probability of coexisting illness and shorter survival.

    People who have had strokes involving the brain stem or those who have had many strokes often have difficulty swallowing, detected through observation. Sometimes signs of the difficulty are subtle, and special X ray studies can be helpful in uncovering the problem. The person should not be fed until it is clear that regular feeding does not present an unacceptable risk of aspiration of food into the lungs.

    Depression that is caused by the stroke is a complication in up to 60 percent of people. If not treated, the depression may persist for many years following the stroke. It can interfere with appetite, sleep patterns, energy level, and extent of cooperation with rehabilitation. Treatment with antidepressant medications can improve performance and rehabilitation, increasing functional capacities. Specialized stroke rehabilitation units may not improve the final neurological problem in stroke victims, but they do appear to improve the person's ability to function. Functional independence is limited in people who have complete paralysis of one half of the body, problems with vision or perceptions, and severe brain stem involvement. Rehabilitation is discussed more completely in Chapter 8.

Meningitis

Meningitis is a bacterial or viral infection of the covering, or meninges (from the Greek and Latin, meaning "membrane"), around the brain and spinal cord.

Causes of Meningitis

In older people, meningitis is most often caused by bacteria and occasionally by viruses. Because of this, any older person who has signs of meningitis should be assumed to have bacterial meningitis until it is proven otherwise. Generally the organisms that cause meningitis in older people are the same as those in younger people. Other organisms can also cause older people to contract meningitis, and a thorough and careful assessment by the physician is always important.

Symptoms of Meningitis

Most older people show the typical features of meningitis: high fever, significant changes in mental function, headache, and a stiff neck. However, some people may not show these changes and may show only an unexplained low-grade fever, changes in mental function, or seizures. This is a serious medical problem and any older person suspected of having meningitis should see a physician right away.

Evaluation of Meningitis

The physician makes the diagnosis of meningitis after performing a spinal tap and examining the spinal fluid. The changes in the spinal fluid that are characteristic of meningitis do not differ in older people compared with younger people.

Treatment of Meningitis

The treatment of bacterial meningitis depends upon the specific laboratory findings, but intravenous antibiotics are always necessary. People usually recover from meningitis if appropriate treatment is given promptly.




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