Neurophysiological evaluation of central-peripheral sensory and motor pudendal fibres

Extensive neurophysiological investigations were carried out in 18 healthy volunteer subjects, and 6 patients with neurological disease. The tests consisted of spinal and scalp somatosensory evoked potentials (SEPs) to stimulation of the dorsal nerve of penis/clitoris, motor evoked potentials (MEPs) from the bulbocavernosus muscle (BC) and anal sphincter (AS) in response to scalp and sacral root stimulation, and measurement of sacral reflex latency (SRL) from BC and AS. In the control subjects, the mean sensory total conduction time (sensory TCT), as measured at the peak of the scalp P40 wave was 40.9 msec (range: 37.8-44.2). The mean sensory central conduction time (sensory CCT = spine-to-scalp conduction time) was 27.0 msec (range: 23.5-30.4). Transcranial brain stimulation was performed by using a magnetic stimulator both at rest and during voluntary contraction of the examined muscle. Sacral root stimulation was performed at rest. Motor total conduction times (motor TCT) to BC and AS muscles were respectively 28.8 and 30.0 msec at rest, and 22.5 and 22.8 msec during contraction. Motor central conduction times (motor CCT) to sacral cord segments controlling BC and AS muscles were respectively 22.4 and 21.2 msec at rest, and 15.1 and 12.4 msec during contraction. The mean latencies of SRL were respectively 31.4 msec in the bulbocavernosus muscle and 35.9 msec in the anal sphincter. Combined or isolated abnormalities of SEPs, MEPs and SRL were found in a small group of patients with neurological disorders primarily or secondarily affecting the genito-urinary tract.