No excessive relapse risk appears to exist for people with multiple sclerosis who undergo surgery that requires anesthesia, researchers report, challenging long-held assumptions associated with MS and surgery.
Their single-site study, “Multiple sclerosis relapse risk in the postoperative period: Effects of invasive surgery and anesthesia,” was published in the Multiple Sclerosis Journal.
Postoperative relapse in MS patients is a common concern. This concern is echoed by neurologists, anesthesiologists, and surgeons, with supporting evidence from small, descriptive case studies.
This perception of surgical risk can have a dampening effect on clinical decisions, causing delays in necessary surgery and preoperative neurology consultations.
A team led by researchers at the University of Michigan (UM) MS Center conducted a retrospective review of MS adult patients being followed at that center, who had undergone an invasive surgical (major or minor) procedure requiring full anesthesia between 2000 and 2016.
The researchers defined relapse as an acute, neurological change lasting for 24 hours or more, without the presence of infection or fever that might indicate a post-surgical complication. Researchers analyzed the patients’ relapse history dating back two years, and up to 90 days after surgery.
Researchers identified 281 MS1 patients who underwent 311 major and 299 minor surgeries at the UM MS Center.
Patients were categorized into demographic groups taking into account age, sex, ethnicity/race, MS type [relapsing MS or progressive MS], smoking status, MS treatment prior to surgery, lesion assessment, surgical procedure type, and relapse dates, both pre- and post-operative.
Statistical analyses were used to identify an association between surgical procedures and relapse risk, in addition to accounting for variability between the different demographic groups.
Results showed a total of 12 relapses following surgery, mostly in white women with relapsing MS. These patients were all significantly younger (mean age of 39, compared to 49 in those without postoperative relapse), and all had a higher frequency of lesions on MRI scans before surgery.
Results were reported as an odds ratio, which is the likelihood that a relapse will occur postoperatively compared to preoperatively. The odds ratio equaled 0.56 without accounting for age, and 0.66 with age adjustment. A value of 1 or below means no significant difference in relapse risk.
Researchers also calculated a rough estimate of yearly relapse rates, where the estimated odds of relapse following surgery were similar to relapse odds before surgery — 5.5% per patient per year, versus 7.1% per patient per year. The results were the same after adjusting for all the demographic variables, and whether the procedure was major or minor.
Based on these results, the team concluded that invasive surgery under full anesthetic does not increase the risk of postoperative MS relapse.
“Although larger, confirmatory studies are necessary, our data challenge long-standing assumptions regarding postoperative relapse risk for individuals with MS, and could inform decision making,” the researchers wrote.