 |
 |
EXTERNAL MOVEMENT PROBLEMS (cont.) 6 STRESS: I haven't heard of professional agreement, but I believe that the need for dopamine replenishment increases with any kind of stress or strenuous activity, either physical or mental. Certainly, PWP find that motor symptoms become more pronounced during periods of stress, such as an argument or in preparation for any kind of trial. I think PWP are subject to a special sort of fatigue, that responds to dopamine. Chronic Fatigue: PWP often complain of constant tiredness or lack of energy, even in the morning after a restful night. "Chronic Fatigue Syndrome" is a recognized clinical condition, but I think it is unrelated to PD because it affects others as well. Ordinary fatigue or exhaustion follows prolonged strenuous exertion, such as an athletic contest or a difficult mountain climb, as muscles are depleted of chemicals that enable them to function, for example blood sugars and oxygen. Ordinary fatigue abates upon prolonged rest, which permits weary muscles to recover their normal chemical state. Quick Exhaustion: What some PWP call "Chronic Fatigue", I prefer to call "Quick Exhaustion". It is not due to running out of blood sugar or oxygen, but mimics the real thing with labored breath and rapid pulse, even in moderate exertion such as climbing a flight of stairs, or doing a tedious manual task. Ignoring this kind of fatigue may trigger pain in an unrelated area, such as the upper back. Its sudden onset and equally quick recovery, after a brief rest or an extra dose of levodopa, shows the connection with PD. In a treadmill test, the technician may notice the unusually quick "cooling off" of pulse and breathing rates. BALANCE: Balance in a normal individual is maintained by many sources: There is the system of the inner ear to detect acceleration and angular position, complex visual cues to sense rotary or linear speed, direction, and position, and there is the internal sense of how weight is distributed between different parts of the feet. Ordinary acts of standing erect or walking involve autonomous coordination of many different muscles, which is lost in PD. The brain's marvelous ability to compensate preserves some aspects of balance, and the PWP's unconscious development of new habits also helps. Posture: The PWP's typical standing posture is easily recognizable. Without doubt it arises from the unaccustomed weakness or tension of certain muscles, and impairment of the many continual reflexes needed to keep standing. In a simple test, the neurologist gives the PWP a gentle push backward, which produces a distinctive reaction. Falling: Falls are frequent in PD, sometimes anticipated and sometimes not. The PWP feels and is much more vulnerable when the footing is unfamiliar or uncertain, for example an icy pavement. As the disease progresses, the patient usually begins to depend on a cane or staff to help keep his balance; later on turns to use of a walker, and still later a wheelchair. EXTERNAL MOVEMENT PROBLEMS (cont.) 7 GAIT: The various forms of the PD gait are also easy to recognize. Failure to swing arms has already been mentioned, but action of the legs and feet also is quite different from normal. Poor balance is partly to blame, and PWP have trouble with the common sobriety test of heel-to-toe walking along a line, and compensate by exaggerating the lateral component of each step. Another compensation is that PWP replace lost autonomous reflexes by habitual attention to each step. Toe Dragging: This annoying gait impairment results in continual stumbling over small obstacles such as doorsills or doormats. The ankle flexor muscle (front of the calf) gets weaker than the extensor (back of the calf). To compensate, one may put more weight on the ball (toe) of each foot. Shuffling: Instead of stepping normally from toe of one foot to the heel of the other, PWP neglect to transfer weight from heel to toe, walking mainly on their heels. Shortened Stride: Seems to be caused mainly by too much weight on heels. Conscious kicking each foot forward in a reduced version of the "goose step" helps to increase stride length, but still not to the normal distance. Festination: The peculiar phenomenon of very short rapid steps while leaning forward, due to combined impairment of lower leg action and balance. Walking faster and faster, the PWP will fall unless he reaches support. Freezing: The PWP cannot start, or suddenly stops, often at a partial obstruction such as a narrow doorway, as though one or both feet were glued to the floor. Hard for others to understand, but the subject is unable to move, and the incidence is very common among PWP. A visual cue such as a pattern on the floor, or an object to step over, "unfreezes" the walking, for reasons that are equally hard to understand. One PWP has invented a visual aid that seems miraculous; a small brightly colored wand extending at a right angle from the lower end of a cane provides something to step over, and eliminates the freezing. The most common form of subliminal compensation for loss of internal guidance is a growing habitual dependence on external stimuli. EXTERNAL MOVEMENT PROBLEMS (cont.) 8 COORDINATION: The PWP tends to lose coordination of voluntary movement such as speech, swallowing, or tasks done with the hands. The loss affects accuracy, speed, and doing more than one thing at a time. Mis-position: Another routine neurologist's test is to have the PWP, with eyes closed and arms extended, touch the tips of forefingers together. The miss distance depends on status of medication dosage as well as progress of the disease. Mis-direction: The PWP, with eyes open, is asked to touch alternately the tip of his nose and the neurologist's index fingertip, as fast as he can. Accuracy is usually poor, and worse with one eye closed. In everyday living activity, the common kitchen task of breaking an egg with a fork (hit the center, not too weak or too strong) becomes a challenge. Slowness: In laboratory tests, researchers have found that the slowness of coordinated movement, such as tapping, is not due entirely to hesitation or caution to improve aim, but largely to a genuine deficit in the speed that is commanded by the brain. In a recent trial curiously, the speed to reach and grasp a stationary object was impaired, but when the object was moving, PWP responded much faster than they thought possible. Bilateral Ability: Psychology researchers have used many ingenious mechanical tests to explore the effect of PD on coordination. For example, in turning a crank with each hand at a preset speed, PWP were about normal. But when the required motions were out of phase, or otherwise different, PWP did much worse than normal control subjects. Fine Guidance: PWP are familiar with decreased dexterity in fine tasks, such as threading a needle or adjusting a watch. The loss is probably due as much to visual defects as to mechanical control. More trouble comes from apparent loss of touch sensitivity in the fingertips, like that experienced when working in cold weather. EXTERNAL MOVEMENT PROBLEMS (cont.) 9 EYE CONTROL: PWP often of difficulty or loss of interest in reading, which they blame on inability to concentrate. The true cause may be in muscles that control eye direction, so that the PWP literally "can't see straight". Jitter: The PD tremor that appears near the time for the next medication dose, or when you are tired, extends also to muscles that direct the eyes. PWP may notice that visual objects, such as printed words, are doing a little dance, that makes reading difficult, especially if the type is small or the lighting dim. Convergence: For both eyes to be aimed at the same point in an object, their position must vary slightly as the object distance changes. This feature is what permits autonomous judgement of distance by humans and other animals (mostly predators) with eyes at the front, rather than sides, of the head. But it also helps greatly in interpretation of detail, to have two similar images that can be merged in the brain. In PD, the control that keeps both eyes focused on a close object such as a printed page is impaired, and the eyes tend to drift into the "distance" position, resulting in a double image. The PWP notices, sometimes every few seconds, that he is using only one eye, and needs to make a conscious effort to pull the images together. SPEECH PROBLEMS: Listeners have trouble understanding PWP because they may speak in a low, slurred monotone, made worse by occasional stuttering. Voice: PWP often need a microphone to be heard, even in a small group, and especially in a noisy place. Training and exercise, such as singing, can help. I have heard of a specialized course called Lee Silverman Voice Training, which is highly recommended. One cause of voice weakness may be failure of the vocal cords in the pharynx to close completely during vocalization. This condition has been treated by injection of collagen into the vocal cords to strengthen them. Slurring: The slurring comes from poor coordination of lips, cheeks and tongue when enunciating certain consonant combinations, as in "rural railroads", etc. For uncertain reasons, some PWP tend to speak very rapidly, adding to the difficulty. Stuttering: Researchers differentiate between loss of verbal fluency, which probably originates in the mental process of speech, and of phonemic fluency, more likely due to poor control of speech muscles. Researchers find that the latter type predominates in PWP. EXTERNAL MOVEMENT PROBLEMS (cont.) 10 FRIGHT REFLEXES: PWP seem generally to be more "jumpy" than others, whether from a constant personality trait, stress associated with the disease, medicines, or from a basic change in neural circuitry. Blink Reflex: In this interesting phenomenon, first described by the philosopher Descartes, everyone blinks involuntarily when an object, apparent or real, seems to be rapidly approaching the face. Researchers find that in PD, the blink reflex is hyperactive. Startle Reflex: Just as normal people jump visibly on hearing a loud unexpected noise, PWP seem to be more sensitive, and may jump even when the noise is a familiar one, such as a telephone ring. The jump is similar to one of internal origin, called myoclonus. Cheers, Joe -- J. R. Bruman (818) 789-3694 3527 Cody Road Sherman Oaks, CA 91403-5013