Causes and Symptoms In general, the term “palsy” describes any type of dysfunction of the motor nerves that impairs or reduces the conscious control of muscles. The paralysis or loss of motor control is usually accompanied or followed by weakness and wasting of the muscles in the affected area.
The most common type of palsy is Bell’s palsy, a paralysis of the seventh cranial nerve, or facial nerve, often accompanied by pain over part or all of the affected area. The number of muscles involved varies. The paralysis usually occurs on one side of the face at a time, with the result that the undamaged muscles of the opposite side pull the facial skin to that side. Typically, the eye on the affected side remains open all the time because the muscles that close it have been affected; attempts by the patient to close the eye merely result in the eyeball rotating upward. The rest of the face on the affected side generally droops but remains flat; the brow fails to wrinkle, and the cheeks never thicken. Smiles and other facial expressions are asymmetrically contorted.
Thorough neurological testing is needed to assess how much damage has been done and which branches of the facial nerve have been affected. If the damage affects either hearing or taste, this finding indicates that the damage is closer to the root of the facial nerve, and the patient’s chances for recovery are correspondingly much lower. If only a few muscles are involved, it indicates that the damage is farther from the root of the nerve, which usually forecasts a better chance of recovery. In most cases, Bell’s palsy is thought to arise from a reduced blood supply to the affected nerves. Viral infection by
herpes simplex or
herpes zoster (shingles) is also a frequent cause; the viral infections are believed to cause demyelination (deterioration of the myelin sheath that insulates nerves) of the affected parts of the facial nerve. Other causes include injuries to the area just below or in front of the external ear resulting from blows to the head, surgery in this region, or other types of trauma.
Another common type of palsy is
cerebral palsy, an impairment of movement and posture caused in most cases by injury, malformation, or other damage to the immature brain. Cerebral palsy is actually a group of paralytic disorders that begin during intrauterine development, at birth, or in early infancy. The extent of the paralysis may vary, often involving large groups of muscles while sparing others. Those muscles that are not totally paralyzed are often uncoordinated in their movements or poorly controlled; this is especially true of large muscle movements such as those of the limbs. In many cases, the patient exhibits a “scissors gait” in which the lower limbs are crossed and the one behind must be swung sideways before it is placed in front of the other limb. In addition to the lack of muscular control of the limbs, other symptoms variously include spasms, athetoid (slow, rhythmic, and wormlike) movements, or muscular rigidity. Speech is in many cases difficult or unclear if the muscles used in speaking are affected.
Mental deterioration may occur in some cases but not in others: Some patients with cerebral palsy are intellectually disabled, while others have managed to display brilliant artistic or literary talents with the use of whatever muscles still function in their bodies. Some cerebral palsy patients also suffer from seizure disorders such as
epilepsy. Almost all cases of cerebral palsy are accompanied by some other type of neurological impairment, the nature of which varies greatly. In general, cerebral palsy is a nonprogressive type of disease; that is, it does not continually worsen. Afflicted individuals generally experience a normal life span, though with impaired motor functions.
The most common types of cerebral palsy are those that occur in infancy or earlier. Of this group, injuries received at birth (during forceps delivery, for example) form one of the largest and most well defined groups. Cerebral hemorrhage, a cause of many cerebral palsies, may occur either during intrauterine life or at birth. Cerebral palsy may also result from embryonic malformations, from injuries received during intrauterine life, or from injuries or other damage during the first two years of life. In addition to birth trauma, many other factors may contribute to a risk of cerebral palsy: premature delivery, breech delivery, toxemia of pregnancy, impairment of the baby’s oxygen supply, maternal infection (especially rubella, also called German measles), premature detachment of the placenta during the birth process, and incompatibility between the Rh blood types of mother and child. Brain injuries caused by low oxygen levels (anoxia or hypoxia) can arise before, during, or after birth and can result from damage to the blood vessels, birth trauma, or infectious diseases such as meningitis or encephalitis.
Cerebral palsies are classified into two general types: pyramidal (or spastic) and extrapyramidal (or nonspastic). The pyramidal or spastic types show muscular spasms and other symptoms that persist with age and hardly vary with changes in emotion, tension, movement, or sleep. The pyramidal tracts of the brain stem are damaged in these forms of cerebral palsy. The extrapyramidal or nonspastic types are more variable and are subdivided into several subtypes according to the types of movement exhibited: none (rigid type), weak (dystonic type), rhythmic and wormlike (athetoid type), or uncoordinated shaking (ataxic type). The extrapyramidal tracts of the brain stem are damaged in all these forms of the disease. Most forms of cerebral palsy can also be described as hemiplegia (involving both extremities on one side of the body only), diplegia (involving both legs more than the arms), bilateral hemiplegia (involving the arms more than the legs), or
quadriplegia (involving all four extremities more or less equally). Attempts to group the various forms of cerebral palsy by their causes have generally resulted in a lack of agreement among experts. One scheme divides the causes into subependymal hemorrhage among premature infants, damage from oxygen deprivation to the growing brain (the vast majority of cases), and developmental abnormalities of the nervous system.
The most common form of cerebral palsy is infantile spastic hemiplegia, which accounts for about one-third of all cerebral palsies. Most cases of
spastic hemiplegia (about 65 percent) are thought to result from birth trauma, either from forceps delivery or from the difficult passage of a very large head through the mother’s pelvic girdle. Another 30 percent arise after birth, during the first year of life, either from head injury or from infections such as meningitis and encephalitis. Only 5 percent of spastic hemiplegias arise before birth from embryonic malformations or from toxemia of pregnancy. The rate at which cerebral palsy occurs is higher for babies born prematurely than for those born at term. It is also higher for large babies that may suffer injury during a difficult passage through the birth canal. In the United States, there is a somewhat higher incidence rate among Caucasians than among African Americans.
Parkinson’s disease (also called paralysis agitans or shaking palsy) is a progressive or degenerative type of palsy. The disease usually produces a tremor that includes a distinctive “pill-rolling” movement of the thumb and forefinger; this tremor usually stops if a voluntary movement of some other kind is begun. Muscle weakness, stiffness, and muscular rigidity are common but with intermittent symptoms that come and go; movements generally become slow and difficult. The muscles involved in chewing and swallowing are often affected in Parkinson’s disease, so patients are often advised to eat high-calorie, semisoft foods that require no chewing and are more easily swallowed than liquids. Involvement of the muscles of facial expression results in a masklike expression that does not alter with changes in emotion. Patients suffering from Parkinson’s disease often have difficulty in initiating voluntary movements; this difficulty is often described by patients as a feeling of “being frozen in place.”
The walking gait of Parkinson’s disease patients is also very characteristic: The body above the waist leans forward, the head and shoulders droop, the feet shuffle slowly (and are barely lifted from the ground), and the arms are generally held slightly flexed and motionless rather than swinging. Many patients break into a trot or a run when they attempt to walk; as a result, patients often fall, most often forward. To prevent such falls, they frequently shuffle forward in very small steps. The shuffling gait is believed to result from a partial paralysis of the extrapyramidal motor system of neurons, which is generally responsible for controlling posture and coordinating motor activities.
Parkinson’s disease is known to result from a disorder in the production of dopamine, a neurotransmitter chemical normally secreted by certain parts of the brain. The affected parts of the brain are the basal ganglia deep within the cerebral hemispheres, and especially the substantia nigra, a deeper structure that sends dopamine-secreting nerve fibers to the basal ganglia. In patients with Parkinson’s disease, cells of the substantia nigra are often degenerate and pale from the loss of normal pigments, but this may be a result, rather than a cause, of the primary defect: an impairment of the brain’s ability to convert dopa (dihydroxyphenylalanine) into the neurotransmitter dopamine.
The chemical n-methyyl-4-phenyl-1,2,3,4-tetrahydropyridine has been found to produce in experimental animals a disease very similar to Parkinson’s disease. For this reason, many researchers suspect that the disease has an environmental cause that leads to the production of a related toxic chemical, one that presumably interferes with the production of dopamine.
Parkinson’s disease is uncommon before the age of forty, but it becomes so common in people over sixty that it is the leading neurological disorder in this age group. In the United States, the incidence rate is about 130 per 100,000 in the general population and is roughly the same in all races and ethnic groups. About 10 to 15 percent of patients show mental deterioration (dementia) as the disease progresses. Patients often experience depression, social withdrawal, and generalized apathy.
Other, less common palsies include brachial birth palsy, Erb’s palsy, Klumpke’s palsy, true or progressive bulbar palsy, pseudobulbar palsy, Féréol-Graux palsy, posticus palsy, lead palsy, scrivener’s palsy, pressure palsy, compression palsy, and creeping or wasting palsy.
Brachial birth palsy is a paralysis of the infant’s arm resulting from an injury received at birth, involving the whole arm, the upper arm only (Erb’s palsy), or the lower arm only (Klumpke’s palsy). Erb’s palsy, a brachial birth palsy of the upper arm, is caused by an injury at birth to the brachial plexus or the posterior roots of the fifth and sixth cervical nerves; the muscles involved generally include the deltoideus, biceps brachii, and brachialis, impairing the raising of the upper arm, flexion of the elbow, or supination movements involving the forearm. In Klumpke’s palsy, which results from an injury at birth, the muscles of the forearm and the small muscles of the hand undergo atrophy; this form is often accompanied by paralysis of the cervical sympathetic nerves.
True or progressive bulbar palsy, a palsy and progressive
atrophy of the muscles of the tongue, lips, palate, pharynx, and larynx, often occurs late in life and is caused by degeneration of the motor neurons leading to these muscles. Twitching or atrophy of the tongue and other affected muscles causes drooling, difficulties in swallowing, and ultimately a respiratory paralysis that results in death. Many experts consider true bulbar palsy to be a manifestation of the same disease that causes amyotrophic lateral sclerosis (ALS), which is popularly known as Lou Gehrig’s disease.
Pseudobulbar palsy (“laughing sickness”) is a paralysis of the lips and tongue that mimics true or progressive bulbar palsy, but it arises in the brain itself and is accompanied by difficulties in swallowing and by spasmodic laughter at inappropriate times. Féréol-Graux palsy, a one-sided (unilateral) paralysis of the motor nucleus of the lateral rectus muscle of one eye and the medial rectus muscle of the other eye, results from damage to the medial longitudinal fasciculus and impairs the ability to direct either eye toward the affected side. Posticus palsy is a paralysis of the posterior cricoarytenoideus muscle (cricoarytenoideus posticus), resulting in the vocal cords being held close to the midline.
Lead palsy is a paralysis of the extensor muscles of the wrist resulting from lead poisoning, while scrivener’s palsy (“writer’s cramp”) is a repetitive motion disorder resulting in damage to the nerve controlling the small muscles of the hand. Pressure palsy is a paralysis caused by repeated or persistent compression of a nerve or nerve trunk. Compression palsy results from nerve compression, especially of the arm, caused by pressure from the use of a crutch (crutch palsy) or from compression of a nerve during sleep. Creeping palsy and wasting palsy are general terms for progressive muscle atrophy, such as that associated with ALS.
Treatment and Therapy
Bell’s palsy is treated by various methods, including the application of warmth, the avoidance of cold drafts, or the administration of vasodilating drugs such as cortisone or antiviral drugs such as acyclovir. In unusual cases, surgery is performed to enlarge the passages through which the facial nerve passes, thus relieving compression on the nerve. In past generations, physicians often recommended treating eyes that could not be closed by taping them shut, especially in sleep. This treatment is no longer recommended. Instead, physicians usually advise patients who cannot close an affected eye to wear dark glasses during the day.
Many patients with Bell’s palsy recover spontaneously on their own. The chances that a particular individual will spontaneously recover depend on the location of the damage and the extent of muscle involvement; the cases with the most favorable outcomes are those in which the damage is more peripheral and fewer muscles are involved. Frequent, repeated testing of each small group of facial muscles is needed to assess the extent of damage and the extent of any recovery.
Diagnosis of cerebral palsy is best made by a trained neurologist through observation of the patient’s spontaneous motor movements and reflex actions. Infants who exhibit any reflex that persists beyond its appropriate age range, or any voluntary motor pattern that fails to develop at the appropriate age, should be examined more carefully for signs of nerve damage. For example, most babies can lift their heads by one month of age and their chests by two months. By three months of age, most babies can raise themselves up on their elbows, and by four months on their wrists. Newborn babies exhibit reflexes such as the Moro reflex, a flexion and “embracing” reflex in reaction to a sudden noise or other sudden stimulus or “startle”; however, the persistence of this reflex beyond six months of age (or its asymmetrical performance) may be indicative of some form of cerebral palsy. Another reflex often used in diagnosis is the “fencer” reflex, or asymmetric tonic neck reflex: Turning the baby’s head toward one side usually causes extension movements in both the arm and leg on the side toward which the chin faces, while flexion movements usually take place on the opposite side of the body. This reflex is present at birth and disappears in a few months; its persistence after six months of age should be considered suspicious.
There is no cure for cerebral palsy. Treatment generally consists of physical rehabilitation and training the patient to use whatever muscles are still capable of being consciously controlled. This is a difficult form of therapy that must be tailored to the needs of each patient because individuals experience unique combinations of motor abilities and disabilities. Few patients with cerebral palsy are capable of walking on their own. Depending on the extent of impairment of muscle movements, some patients may require crutches or braces, while others use motorized wheelchairs. In cases in which there is speech impairment, speech therapy may also be needed to teach the patient to speak more clearly. Most types of cerebral palsy are already present during infancy; therapy for these types is always rather difficult because the patient is learning the necessary motor skills (such as walking or speaking) for the first time. Palsies that arise during adolescence or adulthood respond differently to therapy because the patient is relearning skills that had already been mastered.
Treatment for Parkinson’s disease includes the administration of a number of drugs that are chemically related to dopamine, the missing neurotransmitter. The drug most often used is levodopa, or L-dopa, a derivative of a naturally occurring amino acid in the brain. The drug carbidopa is also given to help deliver most of the levodopa into the brain. Dopamine agonists (enhancers) such as bromocriptine and pergolide are frequently given. The antiviral drug amantadine has also been shown to have effects that counter the disease.
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