Normalproximal anddelayed distal conduction inthe pudendal nervesofpatients withidiopathic (neurogenic) faecal incontinence

TLDR: The latency of the response in the external anal sphincter muscle following transcutaneous stimulation of the cauda equina at the L1 vertebral level was measured, supporting the suggestion that conduction delay in faecal incontinence occurs distally.

Abstract: SUMMARYThelatency oftheresponse intheexternal analsphincter muscle following transcutaneous stimulation ofthecaudaequina attheLivertebral level was measured inninewomen withneurogenic faecal incontinence (mean7-3SD0-7ms)and11normal subjects (mean5-6SD 0-6ms)(p= 0.01). Therewasnodifference inconduction velocity between theLiandL4 vertebral levels thussupporting thesuggestion thatconduction delayinfaecal incontinence occurs distally. Inpatients withidiopathic faecal incontinence there isevidence ofneurogenic damagetothepuborectalis andexternal analsphincter muscles.'-3 We haverecently demonstrated anincreased latency in theresponse oftheexternal analsphincter muscle to trans-rectal stimulation ofthepudendal nerveatthe level oftheischial spine inthese patients.4 Marsden, MertonandMorton'measured thelatency ofthe response inthis muscle intwonormalsubjects following transcutaneous spinal stimulation andwe havenow applied thismethodtoinvestigate our patients withfaecal incontinence. Parks, SwashandUrichsuggested in1977that because thepudendal nerves aretightly boundby connective tissue onleaving thepelvis andentering thepudendal canal, descent ofthepelvic floor duringchildbirth ordefaecation straining mightresult in stretch injury tothese nerves.' Henry,Parksand Swash6 haveshownthattheamountofdescent of thepelvic floor measured inincontinent patients withthedescending perineum syndromewould result ina20%increase inthelength ofthepudendalnerves-more thansufficient tocauseinjury.7 We wished toknowiftheincreased latency found on transrectal stimulation ofthepudendal nervesin incontinent patients waslimited tothedistal portion ofthepudendal nerves, aswouldbeexpected with this entrapment/stretch hypothesis, orwhether con