Chapter 33 Neurophysiologic pelvic floor testing

Abstract

The sacral reflexes are the responses of perinealIpelvic floor muscles to stimulation in the urogenitoanal region. There are two reflexes—anal and the bulbocavernosus, which may be clinically elicited in the lower sacral segments; both have the afferent and efferent limb of their reflex arc in the pudendal nerve, and are centrally integrated at the S2-S4 cord levels. It is possible to use electrical, mechanical, or magnetic stimulation to record these neurophysiologically. Electrical stimulation can be applied at various sites: to the dorsal penile nerve, to the dorsal clitoral nerve, perianally, and at the bladder neck/proximal urethra using a catheter-mounted ring electrode. Sacral reflex responses obtained on perianal or bladder neck/proximal urethra stimulation are higher than sacral reflexes obtained following electrical stimulation of the dorsal penile or clitoral nerve. Pudendal SEP recordings have been widely employed in patients with neurogenic erectile dysfunction, spinal cord lesions, multiple sclerosis, and diabetes. It is easily recorded following electrical stimulation of the dorsal penile or clitoral nerve. The most widely employed technique of obtaining the pudendal terminal motor latency uses the “St. Mark's stimulator”. Using magnetic or electrical stimulation it is possible to stimulate the motor cortex and record a response from the pelvic floor. Concentric and single fiber (SF) EMG electrodes can be used to examine the pelvic floor and sphincters. It has been proposed that sphincter electromyography (EMG) can distinguish between idiopathic Parkinson's diseases and multiple system atrophy.