Screening for Restless Leg Syndrome Warranted in IBS

CHICAGO — Screening patients with irritable bowel syndrome for restless legs syndrome may lead to greater identification of RLS and improved treatment for both conditions, new research suggests.

In a single, community-based gastroenterology center, 29% of 90 patients with irritable bowel syndrome (IBS) based on Rome III criteria were also diagnosed with RLS. The prevalence of RLS in the general population is 1%-10%.

All patients with both IBS and RLS had alterations in the initiation and maintenance of sleep, lead author Dr. P. Patrick Basu and his associates reported in a poster at a meeting on neurogastroenterology and motility. Involuntary jerks and wakefulness during more than 30% of sleep time occurred in 75% and 63% of patients, respectively.

Of the 26 patients with RLS, 62% had diarrhea-predominant IBS, while 4% had constipation-predominant IBS and 33% had mixed IBS, suggesting that the specific pathophysiology of diarrhea-predominant IBS may contribute to or relate to RLS. Previous research has identified an association between small intestinal bacterial overgrowth, a factor that may contribute to IBS, and several sensory disorders including fibromyalgia, interstitial cystitis, and RLS.

“Diagnosis of simultaneous IBS and RLS may provide enhanced therapeutic efficacy for these patients, as some medications, i.e., rifaximin, may provide relief for both conditions,” wrote Dr. Basu, director of gastroenterology, North Shore–Long Island Jewish Health System at Forest Hills, N.Y., and his associates.

Although the data were not included in the poster, 19 of the 26 IBS patients with RLS were treated with the antibiotic rifaximin, with 9 reporting relief of their RLS symptoms, Dr. Basu said. The diagnosis of RLS was made using a standard questionnaire formulated by the International Restless Legs Syndrome Study Group and was confirmed by polysomnography.

Dr. Basu's decision to use rifaximin was prompted by an independent study in 13 patients with IBS and a positive lactulose breath test, an indicator of small intestinal bacterial overgrowth, in which rifaximin 1,200 mg/day for 10 days was associated with at least an 80% improvement from baseline in RLS symptoms in 10 patients and a “great” or “moderate” global GI symptom improvement in 11 patients (Dig. Dis. Sci. 2008;53:1252-6). Five of the 10 patients followed long term (mean 139 days) maintained complete resolution of their RLS symptoms.

Dr. Basu uses rifaximin plus probiotics in his own practice for patients with both RLS and IBS, and is planning to evaluate its efficacy at doses up to 1,400 mg/day in combination with probiotics in 75 IBS patients with RLS.

Two recent studies from Washington University School of Medicine, St. Louis, examined whether RLS is associated with celiac disease and Crohn's disease, because all three conditions are associated with iron deficiency. The incidence of RLS was 35% among 85 patients with celiac disease (Dig. Dis. Sci. 2009 Sept. 3 [Epub ahead of print]) and 43% among 272 consecutive patients with Crohn's disease (Inflammatory Bowel Dis. 2009 July 2 [doi:10.1002/ibd.21001]). The rate of iron deficiency was significantly higher among celiac patients with active RLS versus those without RLS, but there was no difference between Crohn's patients with and without RLS with respect to current iron deficiency.

Dr. Basu and associates reported no conflicts of interest. Support for preparation of the poster was provided by Salix Pharmaceuticals, which markets rifaximin as Xifaxan.