Evidence of pudendal neuropathy in patients with perineal descent and chronic straining at stool.

Abstract

SUMMARY In 17 women with chronic constipation, and abnormal perineal descent on straining at stool, there was more severe neurogenic damage to the external anal sphincter muscle and to its pudendal innervation in those patients with a long history than in those with a short history. These results suggest that recurrent trauma to the pudendal nerves can occur during perineal descent, and that this can lead to denervation and weakness of the external anal sphincter muscle.Between 30% and 66% of patients with faecal incontinence give a long history of excessive straining at stool.' 2 It has been suggested that prolonged straininf during defaecation may cause perineal descent; this in turn may result in recurrent injury to the pudendal nerves and so to progressive denervation atrophy of the external anal sphincter muscle supplied by these nerves. The activity of this muscle is reduced in incontinent patients as has been shown by anorectal manometry and electromyography (EMG).2 4Using single fibre EMG, Neill and Swash5 found an increased motor unit fibre density in the external anal sphincter muscle of incontinent patients. This increased fibre density was consistent with the histological evidence of reinnervation in biopsies of this muscle taken from similar patients.3 6 7 Henry, Parks, and Swash7 found muscle fibre hypertrophy in the external anal sphincter muscle of both continent and incontinent patients with abnormal degrees of perineal descent. They suggested that this hypertrophy represents compensation for the loss of muscle fibres caused by pudendal nerve damage induced by the perineal descent.We have reported an increased terminal motor latency in the pudendal nerves after stimulation of these nerves at the level of the ischial spine in patients with neurogenic faecal incontinence.' This work supports our suggestion that the site of damage to this nerve may be at the point where it passes beneath the sacrospinous ligament.3 We have now tested this hypothesis that the pudendal nerves may be damaged in patients with perineal descent and Address for correspondence: Dr M Swash, Neurological Department, The London Hospital, London El 1BB. Received for publication 29 January 1984 1279 chronic constipation by direct measurement of pudendal nerve conduction. Methods PATIENTSSeventeen women with a history of chronic constipation were studied. All had perineal descent on straining. Eleven patients, aged 34-70 years (mean 48-1±9.7 years) had been intermittently straining at stool for between 20 and 50 years (mean 26 years), whereas in the other six patients aged 22-25 years (mean 23*8±1-5 years) the history of straining was of 10 years or less (mean 6-8 years). The mean frequency of straining per week was similar in both groups; 6-0 and 6-3 respectively. None of the six young patients was parous and none had had pelvic surgery, whereas nine of the group with a long history of straining were parous and two of these women gave a history of difficult labour. In addition three patients in this group had had a hysterect...

Study of the Electrical and Mechanical Activity of the Rectum: An Experimental Study

“…It is regulated and coordinated by motor mecha nisms and reflex actions [ 1 -3]. Disturbance of these mechanisms leads to defecation disor ders [4][5][6][7], Many of these disorders are related to disturbed motility of the rectum at defeca tion [8][9][10][11][12][13].…”

Actualización del síndrome de atrapamiento del nervio pudendo: enfoque anatómico-quirúrgico, diagnóstico y terapéutico

“…El estreñ imiento cró nico y el descenso perineal es una de las primeras causas aportadas como desencadenantes del SANP 14 . Shafik hace menció n en un interesante artículo sobre la importancia del acompañ amiento del prolapso rectal a la incontinencia rectal para la producció n del SANP.…”

Current Advances and Controversies in the Surgical Therapy for Anorectal Motility Disorders

“…Constipation has been reported to be the predominant symp tom in 19-65% of patients [26][27][28], Fecal incontinence is also commonly associated with rectal prolapse [29] and is a common long-term complication. This may be due to a combination of repeated traction on the pu dendal nerves, abnormal perineal descent and progressive anal dilatation [16,22,30], Pro gressive anal dilatation is thought to lead to low resting [31] and squeeze pressures [32,33]. Internal anal sphincter dysfunction is the result of chronic stretching, activation of the rectoanal inhibitory reflex [34] and disturbed anorectal sensation [35], External anal sphincter weakness, on the other hand, mani fested by reduced squeeze pressure, is the result of denervation [32,33].…”

“…This will ultimately result in a neuropathy and with progressive denervation, the external sphincter will become incompetent [15], The severity of pudendal neuropathy has been Current Advances and Controversies in the Surgical Therapy for Anorectal Motility Disorders found to correlate to the onset magnitude of straining [16],…”