TUESDAY, June 30, 2026 (HealthDay News) -- History of adenotonsillectomy is associated with increased odds of pediatric-onset multiple sclerosis (POMS), according to a study published online May 29 in Multiple Sclerosis Journal.Gina Chang, from the University of California, San Francisco, and colleagues recruited POMS participants and controls from 16 pediatric multiple sclerosis (MS) clinics between Nov. 1, 2011 and July 1, 2017 to examine the potential role of adenotonsillectomy in POMS risk and relapse rate. The case-control analysis included 359 participants with POMS and 560 controls.The researchers found that individuals with a history of adenotonsillectomy had increased odds of MS (adjusted odds ratio, 1.63). Adenotonsillectomy was associated with a twofold increase in annualized relapse rate among the 239 POMS participants with available follow-up data (adjusted incidence rate ratio, 2.00)."While we cannot establish a causal role for adenotonsillectomy in POMS given the limitations of our data, one possible hypothesis is that removal of these immunologically active tissues influences MS susceptibility and disease activity by contributing to immune dysregulation," the authors write.Abstract/Full Text.Sign up for our weekly HealthDay newsletter