Anorectal sensitivity in patients with obstructed defaecation

Abstract

Patients with obstructed defaecation (OD) perform major defaecatory efforts that lead progressively to pudendal motor neuropathy. Anorectal sensory function in these patients and its possible influence in the pathogenesis of the disease have been little studied. In the present paper we investigated anorectal sensitivity to electric and thermal stimuli in patients with OD, and studied the possible existence of pudendal sensory neuropathy associated to their known pudendal motor neuropathy. Forty subjects were divided into two groups: 21 healthy controls (11 females and 10 males; mean age 51.8 +/- 11 years, range 33-67) and 19 patients with OD (18 females and 1 male; mean age 48 +/- 15 years, range 20-71). The patients with OD suffered constipation and an obstruction sensation upon defaecating, even in the case of soft stools. Clinical perineometry, manometry, pudendal motor latency studies, external anal sphincter single fibre electromyography and the evaluation of sensitivity to electric and thermal stimuli were carried out in all cases. All pudendal motor function parameters showed statistically significant differences between the two groups. In the controls the electrical sensitivity threshold was minimal in the mid anal canal, where sensory receptor presence is greater. Sensitivity was significantly higher in the upper and lower anal canal regions (P < 0.05), and much higher in the rectum (P < 0.001). A similar sensory profile was recorded in the patients with OD, though with significantly higher thresholds at all points with respect to the controls. The thermal stimulus thresholds in the lower and middle anal canal were significantly smaller than in the upper canal region and rectum, and the thresholds were again higher among the patients with OD than among the controls. In all cases the thresholds for heat were lower than for cold stimuli. In both groups the motor function parameters were correlated with the sensory function variables, and the latter between themselves. Patients with OD presented sensory deterioration at all points studied in the anal canal and rectum. Sensory pudendal neuropathy was found to be associated with the pudental motor neuropathy.

Rectal Hyposensitivity

“…46,No. 12 Conversely, it is possible that the primary abnormality is impairment of rectal sensation, and this results in OD. Another group of patients with symptoms of infrequency of defecation have no demonstrable abnormality on investigation at all, and this is rather difficult to explain.…”

“…The term rectal hyposensitivity (RH), defined by elevation of sensory thresholds beyond the normal range, relates to impaired or blunted rectal sensory function and has frequently been reported in patients with chronic constipation [9][10][11][12] and idiopathic fecal incontinence. [13][14][15][16][17] Moreover, it has been reported to be a predictor of poor outcome in the treatment of fecal incontinence with biofeedback techniques 18,19 and surgery.…”

Perineal Rectocele: A Cause of Constipation

“…The healthy volunteers had had normal deliveries. They had no anorectal complaint and had a mean stool frequency of 9.7 Ϯ 1.3 per week (range, [7][8][9][10][11][12]. Defecography showed no rectocele.…”

“…It may be attributed to recognizable causes [1][2][3][4][5][6][7][8][9][10] ; however, there are still groups of patients in whom constipation is considered idiopathic. Studies have ascribed idiopathic constipation (IC) to psychogenic causes, disturbed hormonal balance, genetic factors, disordered absorption, and endogenous opioids.…”

Rectal hyposensitivity and functional anorectal outlet obstruction are common entities in patients with functional constipation but are not significantly associated

“…Straining and excessive pelvic floor descent is commonly seen in patients with functional anorectal outlet obstruction. These events may cause stretching of the pudendal or hindgut autonomic nerves, resulting in neuropathy [4], which could precipitate RH [5]. …”