2. DEGENERATIVE - PARKINSON'S DISEASE
A Sample Case: A 62 yr old woman noticed a painful cramping in her left foot which caused her to go to the doctor. Co-workers noticed a slight shakiness in her hands and, in retrospect, described her face as less animated and her walk as slower. After a period of time she had difficulty rising from her chair and when walking had suffered several falls; she tended to attribute these to her generalized tired feeling.
Her past medical history revealed several disorders unrelated to her current complaints. Her general physical condition was good. The neurologic exam showed her to be alert, well-oriented with respect to time and place, and with good comprehension. Her speech was clear though somewhat soft. Blinking was somewhat infrequent and her eyes seemed to be open wide. There was a slight tremor in her lower jaw that was not obvious when she spoke. There were no other obvious cranial nerve signs. Sensory examination was normal as were strength and deep tendon reflexes. There was however increased resistance to passive stretch in both flexors and extensors at the wrist, elbow, and shoulder. The hand, but not the foot, showed a rhythmic tremor of 4-5/sec which was suppressed when she was asked to write or to extend her hands; her writing seemed to be unusually small, i.e., micrographia. The patient was slow to rise from her seated position and if pushed from in front or back when standing tended to move with many short steps (antero-, and retropulsion). There was little swinging of her arms when she walked but there was no dysmetria or other cerebellar signs.
Early signs of Parkinsonís disease are usually subtle and may involve one side before the other or include the upper and/or lower extremities. A tiredness, fatigue, and cramping may be due to the advancing rigidity. Psychologic depression and the most severe motor signs may occur late in the disease.
Her cranial nerves were largely unaffected except for the tremor of the jaw and the wide, unblinking eyelids. The expressionless face ("masked facies") is a sign of this disease. Strength and reflexes of the limbs, upper and lower, were normal. There was resistance to passive stretch in the opposing flexors and extensors upper extremities, i.e, "rigidity"; the presence of a noticeable concomitant tremor is described as "cogwheel" rigidity. In later stages of the disease the body is flexed at the waist and at the elbow, an indication that the strength of the flexors in rigidity is greater than that of the extensors. Her hand demonstrated tremor and micrographia. The latter is an indication of the slow movement with decreased amplitude (bradykinesia) which characterizes all movements in Parkinsonís disease. Difficulty in rising from a chair or bed, lack of arm swing in walking, tripping, and short steps are all suggestive of Parkinsonian bradykinesia, rigidity, and inability to make the automatic postural adjustments necessary in standing and walking.
Bradykinesia, rigidity, and tremor at rest are the cardinal signs of Parkinsonís disease, a chronic, progressive, degenerative disease associated with loss of neurons in the substantia nigra. The slow onset indicates that its etiology is not vascular; the eventual bilateral symptoms indicates that it is not a neoplasm. The substantia nigra has controlling influence at many levels related to the basal ganglia and movement especially via its input to the caudate/putamen.