Table 1: Mechanisms of anorectal dysfunction.

Assessment tool Symptom Sample size MS severity Results Reference Anorectal manometry Con 21 EDDS: 5.3 Decreased rectoanal inhibitory reflex [23] Con or FI 39 EDSS: 5 No difference based on symptom patterns [22] DSS : 5 Con 13 DSS : 8 Weak external sphincter: 62; impaired straining: 82 [11] Con 30 EDSS: 6 Lower squeeze pressure, impaired valsalva pressures [12] Con and FI 11 Lower sphincter pressures in women [35] Con and FI 23 Wheelchair: 9 Abnormal squeeze pressure in a subset [36] Con and FI 16 Impaired amplitude and duration of squeeze pressure [19] Con and FI 52 EDSS: 4.13 Decreased squeeze pressures [16] FI 6 Markedly reduced squeeze pressure [32] FI 12 Lower squeeze pressure in women only after childbirth [27] Con 9 EDSS: 9.6 Decreased squeeze pressure [13] Recto-anal sensitivity Con and FI 39 EDSS: 5 No differences in rectal or anal sensory thresholds [22] Con and FI 11 Normal rectal sensory thresholds [35] FI 5 Abnormal sensory threshold to distension in 3/5 patients [19] Con 9 EDSS: 9.6 Normal rectal and anal sensory thresholds [13] FI 6 Normal rectal sensory thresholds [32] Con and FI 52 EDSS: 4.13 Normal rectal sensory thresholds [16] Con and FI 30 EDSS: 6 Abnormal sensory threshold to distension in 15 patients [12]

Con: constipation; FI: fecal incontinence; EDSS: expanded disability status scale.