Autonomic Rectal Dysfunction in Patients With Multiple Sclerosis and Bowel Symptoms Is Secondary to Spinal Cord Disease

BACKGROUND: Most patients with multiple sclerosis report bowel symptoms, but the underlying pathophysiology is unclear. OBJECTIVE: We hypothesize that rectal dysfunction in multiple sclerosis is secondary to involvement of the spinal cord by the disease and that this can be measured by assessing rectal compliance. DESIGN: This was a case-control study. SETTINGS: The study took place in a neurogastroenterology clinic and tertiary referral center. PATIENTS: Forty-five patients with multiple sclerosis, 19 with a spinal cord injury above T5, and 25 normal control subjects were included in this study. Patients with multiple sclerosis were subdivided into 2 groups according to the Expanded Disability Status Scale, below 5 (multiple sclerosis minor disability, n = 25) or above 5 (multiple sclerosis major disability, n = 20), as a reflection of spinal cord involvement. MAIN OUTCOME MEASURES: Rectal compliance, Wexner constipation, and Wexner incontinence scores were measured. RESULTS: Data are presented as mean and SD. Expanded Disability Status Scale correlated with rectal compliance but not with Wexner constipation or Wexner incontinence scores. Post hoc analysis showed no significant difference in Wexner constipation and Wexner incontinence between the 2 multiple sclerosis groups. LIMITATIONS: Limitations to this study include the lack of an asymptomatic group with multiple sclerosis and the small sample size to evaluate bowel symptoms. CONCLUSIONS: Rectal compliance correlates with disability, and observed alterations in the rectal properties are secondary to spinal cord involvement. Our findings suggest that, in patients with neurologic impairment, rectal compliance is a surrogate of reflex activity of the spinal cord regulating rectal function and both a potential predictor of outcome and target for treatment. Multiple sclerosis patient subgroups had similar symptom burden, arguing that bowel dysfunction is multifactorial.