Electrophysiological evidence for afferent nerve fibers in human ventral roots

This study was designed to test the hypothesis that ventral roots in humans contain afferent nerve fibers. We made direct electrophysiological recordi ngs of compound nerve action potentials in dorsal and ventral roots in chil dren undergoing selective dorsal rhizotomy for spastic cerebral palsy. We s timulated the saphenous or sural nerves, which are pure sensory nerves, wit h electrical stimuli while systematically recording from ventral and dorsal roots from L3 to S2. In addition to the dorsal root nerve action potential s which we expected, we found smaller compound nerve action potentials, whi ch were clearly afferent, in the ventral roots. This confirms the limited a mount of experimental evidence that ventral roots do contain some afferent nerve fibers. The functional significance of these observations is not yet clear. (C) 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 410-415, 2000.