Parkinson's disease does not affect everyone the same way. In some people the disease progresses quickly, in others it does not. Although some people become severely disabled, others experience only minor motor disruptions. Tremor is the major symptom for some patients, while for others tremor is only a minor complaint and different symptoms are more troublesome.
- Tremor. The tremor associated with Parkinson's disease has a characteristic appearance. Typically, the tremor takes the form of a rhythmic back-and-forth motion of the thumb and forefinger at three beats per second. This is sometimes called "pill rolling." Tremor usually begins in a hand, although sometimes a foot or the jaw is affected first. It is most obvious when the hand is at rest or when a person is under stress. In three out of four patients, the tremor may affect only one part or side of the body, especially during the early stages of the disease. Later it may become more general. Tremor is rarely disabling and it usually disappears during sleep or improves with intentional movement.
- Rigidity. Rigidity, or a resistance to movement, affects most parkinsonian patients. A major principle of body movement is that all muscles have an opposing muscle. Movement is possible not just because one muscle becomes more active, but because the opposing muscle relaxes. In Parkinson's disease, rigidity comes about when, in response to signals from the brain, the delicate balance of opposing muscles is disturbed. The muscles remain constantly tensed and contracted so that the person aches or feels stiff or weak. The rigidity becomes obvious when another person tries to move the patient's arm, which will move only in ratchet-like or short, jerky movements known as "cogwheel" rigidity.
- Bradykinesia. Bradykinesia, or the slowing down and loss of spontaneous and automatic movement, is particularly frustrating because it is unpredictable. One moment the patient can move easily. The next moment he or she may need help. This may well be the most disabling and distressing symptom of the disease because the patient cannot rapidly perform routine movements. Activities once performed quickly and easily -- such as washing or dressing -- may take several hours.
- Postural instability. Postural instability, or impaired balance and coordination, causes patients to develop a forward or backward lean and to fall easily. When bumped from the front or when starting to walk, patients with a backward lean have a tendency to step backwards, which is known as retropulsion. Postural instability can cause patients to have a stooped posture in which the head is bowed and the shoulders are drooped.
As the disease progresses, walking may be affected. Patients may halt in mid-stride and "freeze" in place, possibly even toppling over. Or patients may walk with a series of quick, small steps as if hurrying forward to keep balance. This is known as festination.
