Tendon reflex variability and method of stimulation.

Human tendon reflexes show large fluctuations, even when accurate mechanical instruments are used for stimulation. To examine the contribution of stimulus factors to reflex variability two methods of stimulation were compared in healthy subjects. One method consisted of a normal hand-held reflex hammer, with a transducer to measure stimulus intensity. The results with this hammer, both after maximal stimuli and after stimuli over a wide range of intensities, showed a similar variability of reflexes as with a more accurate instrumental stimulator. In previous studies in human subjects an equal or larger variability of reflexes was found. It is concluded that for many applications a simple hand-held reflex hammer gives equally reliable results as more complicated instrumental stimulators.