The recto-anal inhibitory reflex (rair): abnormal response in diabetics suggests an intrinsic neuro-enteropathy

Abstract

INTRODUCTION: The recto-anal inhihilory reflex (RAIR) is characterized by reflex relaxation of die anal canal in response to electrical stimulation of the rectaJ mucosa, and is mediated by nitrergic neural plexuses within the wall. Im-painnent of this reflex may lead lo incontinence. AIM: To measure anal canal pressures, anal mueosal electrosensation and RAIR in diabetic patients and corre¬late these measurements with incontinence for gas or faeces. METHODS: Anal canal pressure, RAIR and continence was evaluated in 30 diabetic patients [Male : Female = 13:17, median age 57 years (range 37 - 70) ], and these data were compared with similar data obtained from 22 age and sex matched 'healthy' controls [Male:Female = 9:13,age51 years (range 19-65)]. Median duration of diabetes was 8 years(rangc 3-30). 12 (40%) of Uic 30 diabetes had impaired continence for gas (n = 12) and liquid faeces (n =3). None oi'the controls had incontinence. RESULTS : Maximum resting anal canal pressure (MRP) was [median (range)]: Patients 30 mml Ig (20 -75) vs. Controls 40mmHg (20-105). P=0.61. Maximum squeeze pressure (MSP) [median (range)] : Patients 65 mmllg (30-150) vs. Controls 84mmHg (35 -230), P = 0.59. Threshold rectal mueosal elec(rosensation (RMES-T) [median(range)]: Patients 27 mA (5-40) vs. Controls 13mA (5-28), P = 0.03. Maximum tolerable rectal mueosal electrosensation [median(rangc)]: Patients 40mA (20-60) vs. Controls 20mA (10-30), P=0.042 (all comparisons using Wiicoxon rank test). RAIR was present in 8, abnormal in 5 (1 with inconti¬nence), and absent in 17 (11 with incontinence) diabetics while it was present in 18 and abnormal in 4 controls (testof proportion, P = 0.031). CONCLUSIONS: RAIR was impaired in significantly more patients with diabetes than controls implying impairment of intrinsic neuronal function. All diabetic patients with incontinence had impaired or absent RAIR. Impairment of this reflex may be a useful predictor of incontinence in diabetics.