The study below documents that in general pwMS with constipation have loss of sphincter tone (strength) at rest and during contraction compared to non-MS patients. In the subgroup of patients with faecal incontinence, rectal sensitivity threshold was lower in patients with MS than in other patients. In other words when faeces enters the rectum the threshold that triggers the defaecation reflex is lower. Finally, patients with MS had a decrease in the difference in resting anal pressure before and after maximum squeeze maneuvers, which suggests post-contraction sphincter spasticity. All this indicates impaired pelvic floor coordination in pwMS.
Knowing what is wrong with rectal and anal function in patients with bowel problems can help with specific therapies targeting specific symptoms, i.e. constipation, faecal hesitancy (difficult initiating a bowel action), incomplete emptying, faecal urgency, urgency incontinence, overflow diarrhoea, excessive bloating, excessive flatus, etc.
Bowel function is one of the hidden MS symptoms; patients often suffer in silence and their HCPs often fail to ask about bowel problems. Over the lifetime of the disease the majority of pwMS develop bowel problems so it is important for you to realise that a lot can be done to help you. If you have bowel problems can you please discuss these with your neurologist or MS clinical nurse specialist.
On the other side of the coin if MS is treated early and effectively before the neuronal pathways that control bowel function are damaged then these issues can hopefully be avoided or at least delayed.
Marola et al. Anal sphincter dysfunction in multiple sclerosis: an observation manometric study. Open Med (Wars). 2016;11(1):509-517.
Background: Constipation, obstructed defaecation, and faecal incontinence are frequent complaints in multiple sclerosis. The literature on the pathophysiological mechanisms underlying these disorders is scant.
Methods: Using anorectal manometry, we compared the anorectal function in patients with and without multiple sclerosis. 136 patients referred from our Center for Multiple Sclerosis to the Coloproctology Outpatient Clinic, between January 2005 and December 2011, were enrolled. The patients were divided into four groups: multiple sclerosis patients with constipation (group A); multiple sclerosis patients with faecal incontinence (group B); non-multiple sclerosis patients with constipation (group C); non-multiple sclerosis patients with faecal incontinence (group D). Anorectal manometry was performed to measure: resting anal pressure; maximum squeeze pressure; rectoanal inhibitory reflex; filling pressure and urge pressure. The difference between resting anal pressure before and after maximum squeeze maneuvers was defined as the change in resting anal pressure calculated for each patient.
Results: Group A patients were noted to have greater sphincter hypotonia (reduced tone) at rest and during contraction compared with those in group C (p=0.02); the rectal sensitivity threshold was lower in group B than in group D patients (p=0.02). No voluntary post-contraction sphincter relaxation was observed in either group A or group B patients (p=0.891 and p=0.939, respectively).
Conclusions: The decrease in the difference in resting anal pressure before and after maximum squeeze maneuvers suggests post-contraction sphincter spasticity, indicating impaired pelvic floor coordination in multiple sclerosis patients. A knowledge of manometric alterations in such patients may be clinically relevant in the selection of patients for appropriate treatments and for planning targeted rehabilitation therapy.