The aim of this study was to define pelvic floor function in patients with multiple sclerosis and bowel dysfunction, either incontinence (MSI) or defecation difficulties without incontinence (MSC). Normal controls and patients with idiopathic neurogenic faecal incontinence without multiple sclerosis (FI, disease controls) were also studied. Thirty eight multiple sclerosis patients (20 incontinent, 18 incontinent) 73 normal controls, and 91 FI patients were studied. The FI group showed the characteristic combined sensorimotor deficit previously described in these patients of low resting and voluntary contraction anal pressures, increased sensory threshold to mucosal stimulation, and increased pudendal nerve terminal motor latencies and fibre densities. MSI patients had significantly lower anal resting pressures (80 (30-140) cm H2O, median (range) v 98 (30-200), normal controls, p=0.002) and both MSC and MSI patients had significantly lower anal maximum voluntary contraction pressures (65 (0-260) cm H2O, MSC and 25 (0-100), MSI v 120 (30-300), normal controls, p=<0.0004) and higher external anal sphincter fibre densities (1.7 (1.1-2.6), MSC and 1.7 (1.1-2.4), MSI v 1.5 (1.1-1.75), normal controls, p<0.006) compared with normal controls but pudendal nerve terminal motor latencies were similar and no sensory deficit was found. This contrasted with the idiopathic faecal incontinent patients who, in addition to significantly higher fibre densities (1.8 (1.1-3), p=0.0010 had increased pudendal latencies (2.5 (1.1-5.5) mS v 2.08 (1.4-2.6), p=0.001) compared with normal controls. The idiopathic faecal incontinent group had significantly lower resting anal pressures (50 (10-160) Cm H2O, p=0.02) than the MSI group. Comparison with the incontinent and continent multiple sclerosis groups showed that incontinence was associated with lower voluntary anal contraction pressures (25 (0-100) v 65 (0-260), p=0.03) but that there were no other differences between these two groups. Pelvic floor function is considerably disturbed in multiple sclerosis, showing muscular weakness with preservation of peripheral motor nerve conduction, providing indirect evidence that this is mainly a result of lesions within the central nervous system.
