Evoked potentials in a man with a complete large myelinated fibre sensory neuropathy below the neck

Cortical somatosensory evoked potentials (SEPs) were recorded from a man with a severe neuropathy without touch and proprioception below the neck. Peripheral neurophysiological tests showed a complete large myelinated fibre sensory neuropathy. Sensory threshold to electrical stimulation of the median nerve was 15 mA (normal 2-4 mA). With a stimulus of 39 mA, duration 400 microsecons, applied at the wrist a cortical SEP was recorded with a latency of 84 msec, giving a propagation velocity of 11.9 m/sec. At stimulation rates of above 3.3 Hz the SEP was absent. It is concluded that the SEPs recorded were conducted along A delta peripheral fibres.