Pelvic somato-visceral reflexes after spinal cord injury: measures of functional loss and partial preservation.

For people with spinal cord injuries, the impact of bladder, bowel and sexual problems on quality of life and lost opportunities can be devastating. Supra-sacral spinal lesions can cause incontinence by interrupting those pathways that normally coordinate the function of the bladder, bowel and sphincters. From a scientific perspective, neural control of the pelvic organs is one of the most intriguing in the body, involving both somatic and autonomic pathways participating in an exquisitely fine integration of lumbo-sacral reflexes. This chapter aims to review briefly those aspects of neural control of the pelvic organs that are amenable to neurophysiological examination in man. More specifically, it will focus in greater detail on the interactions of somatic and autonomic lumbo-sacral pathways responsible for coordinating the bladder and sphincters. Where appropriate, it will make comparisons with those controlling the bowel. It will describe how measurement of pelvic floor and sphincter reflexes can be used to assess the modulatory effects of sacral autonomic pathways on sacral somatic reflexes and vice versa including the so-called "guarding reflex" and vesical inhibitory reflexes. Aberrant activity following spinal cord injury (SCI), such as bladder hyperreflexia and sphincter dyssynergia, will be discussed in relation to these reflexes. The effects of volitional modulation of pelvic floor reflexes in people with both complete and incomplete lesions will be described. Finally, the chapter will address the possible utility of neurophysiological measures for complementing the established neurological classification and the assessment of somatic sensory-motor impairment in SCI.