Characteristics of multisegmental monosynaptic responses of leg muscles in subjects with lumber nerve compression

The reflex motor responses of 16 symmetric leg muscles evoked by transcutaneous electric stimulation of spinal nerves at the L2-L3 or L3-L4 level were studied in subjects with signs of lumbar nerve compression. The evoked responses agreed with Ia afferent activation through monosynaptic neuronal circuits. Their monosynaptic nature was demonstrated by amplitude changes in response to a conditioning stimulus and continuous tendon vibration. Multisegmental monosynaptic responses (MMRs) of large distal flexors containing large numbers of slow motor units were subjected to the greatest modifications against a background of lumbar nerve compression.