REFLEX TIME OF THE KNEE JERK IN CONTROLS, SPASTICITY, RADICULOPATHY AND NEUROPATHY

The reflex time was determined by means of a computerized device. In c ontrols reflex time varied from 15.8 to 22.2 ms, depending on age and body size. In spasticity reflex time was shortened in most patients, p robably because impulse transmission at the spinal synapse is shortene d due to an increased excitability of the anterior horn cells. In L4 r oot compression and in most patients with neuropathy reflex time was p rolonged, even in patients with normal motor and sensory conduction ve locity. Prolongation of reflex time is mainly due to a delayed excitat ory postsynaptic potential (EPSP) rising phase at the spinal synapses.