THE ANKLE JERK is useful for the diagnosis of thyroid gland dysfunction. Lengthening of the reflex time in myxedema was thought to be independent of nervous system influences.1 Previous studies reported the "reflex time" measured from the onset of the stimulus to half relaxation. This measurement was the sum of several factors: latency, speed of contraction, and half relaxation time of the muscle, each one of which could have been independently affected by age of the subjects or disorders in the central or peripheral nervous systems.
It was thought worthwhile, therefore, to determine whether these phases of the reflex changed with age or were influenced by neurological disease.
Materials and Methods
There were 102 subjects studied, including 48 controls. The controls were divided into two groups: controls ranging in age from 50 to 95 years in one group and from 9 months to 21 years in the other.