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Irritable Bowel Syndrome and Multiple Sclerosis: What’s the Connection?

October 27, 2021

Multiple Sclerosis (MS) is an inflammatory disorder of the central nervous system with major impacts on neural circuits found in the brain and spinal cord. Disruptions in these neural circuits can lead to a range of problems, including issues with gut function. David Levinthal, MD, PhD, director of the Neurogastroenterology and Motility Center at UPMC and assistant professor of medicine in the Division of Gastroenterology, Hepatology, and Nutrition at the University of Pittsburgh, has been conducting research that investigates the relationship between MS and gastrointestinal (GI) function.

While gastroenterology is a broader term that focuses on treatments and disorders within the gastrointestinal tract, neurogastroenterology centers on the neural regulation of gut movements (“motility”) and sensations. There’s a hard-wired, brain-gut connection made up of nerves and neurotransmitters, which constantly communicate back and forth between the central nervous system and the gut. These communications may not be consciously perceived but are needed for the gut to operate correctly.

Dr. Levinthal’s research has focused on gastrointestinal problems experienced among patients with MS that include disruptions of both sensations and actions of the gut. His team found that about two-thirds of MS patients experience at least one chronic gastrointestinal symptom, and that 20% of MS patients experience symptoms compatible with irritable bowel syndrome (IBS). This rate of IBS symptoms is a little more than twice the rate seen in the general population.

Irritable Bowel Syndrome and Multiple Sclerosis – The Connection

The central nervous system influences gut function via the vagus and sympathetic nerves, which make up the peripheral autonomic nervous system. These nerves are also essential in regulating other organs and programming the body’s physiological state, such as heart rate, breathing rate, and blood pressure, in addition to digestive function. Dr. Levinthal and his colleagues are developing techniques to map the neural connections between the brain and gut, as well as other organs. These neural maps will help physicians better understand the connection between MS and gastrointestinal issues, and one day lead to targeted treatments for patients that suffer from these issues.

Common Challenges

MS patients are likely to develop GI disorders after diagnosis, with deficits in swallowing and defecation that form the two primary challenges faced by patients with MS. Dr. Levinthal’s research has found that about 20% of MS patients experience swallowing problems, and 40% of MS patients suffer from constipation, a rate about four times that seen in the general population. Both processes involve the neural control and fine-tuned coordination of several skeletal muscles, and MS can impair these neural pathways. For example, evacuating bowel movements requires contractions of abdominal muscles to generate considerable force to move stool. If a patient has trouble contracting those abdominal muscles, this may result in constipation or other colon complications.

Treatment Options

MS may also affect the colon’s speed of contractions. The colon’s function is to reabsorb fluid and propel waste for evacuation. If stool resides in the colon for an extended period of time, waste may be more solid or hard in consistency and be particularly difficult to expel. If a patient is constipated, increasing fiber intake may help modify the fluid content of the colon and influence the speed of colon contractions. There are also many different medications that can help patients influence the gut for easier bowel movements, such as over-the-counter medicines such as senna, PEG-3350, or prescription medications such as linaclotide or prucalopride.  

MS also increases the likelihood of experiencing fecal incontinence or involuntary stool leakage, which results from the weakening of the anal sphincter muscles. That muscle’s tone matters greatly, as it functions as a “gate” to regulate the flow of waste out of the rectum. Given that firmer stool is less likely to ‘leak’, bulking stools using fiber supplementation is one of the best means of combatting fecal incontinence.

Research Developments

Dr. Levinthal’s research group is currently in the early stages of developing non-invasive mapping techniques using a magnetic stimulator, to locate brain sources of GI control. This work may help understand where GI problems begin in patients with MS and also more broadly shed light on what brain areas are involved in organ control. With this information, physicians will gain a clearer understanding of how MS affects organ function, and pave the way toward brain-based treatments for IBS and other gut dysfunctions in MS.