A recent Multiple Sclerosis Journal study that included data from 281 patients and 609 surgeries suggests post-operative MS relapse risk does not significantly differ from pre-operative relapse risk.

No prior studies have systematically investigated the influence of surgery or anesthesia administration on relapse risk, but it's a large concern in clinical practice.

LISTEN UP: Add the new Michigan Medicine News Break to your Alexa-enabled device, or subscribe to our daily updates on iTunes, Google Play and Stitcher.

This concern greatly impacts clinical decision making. These decisions, like neurology consultations for pre-operative clearance, can delay important surgeries, potentially unnecessarily.

Lindsey De Lott, M.D., assistant professor of neurology and first author of the manuscript, says she hopes this research gives physicians and patients the confidence in moving forward in the procedural decision making process.

"The idea that patients with MS might be at an increased risk of relapse following surgery isn't necessarily the case, so we need to be careful delaying important surgeries," says De Lott.

De Lott and senior author Tiffany Braley, M.D., M.S., associate professor of neurology and multiple sclerosis specialist, hypothesized that In the absence of post-operative complications, anesthesia exposure or surgery would not trigger functional decline or symptom recurrence.

Braley says the "vast majority" of her patients do well after surgery without evidence of relapse. So where do these concerns come from?

"In the rare instance when we have encountered a person with MS who developed neurological symptoms after surgery, the symptoms could usually be explained by a fever or infection," says Braley, "yet, the limited research previously done on this topic did not take these factors into account." 

Limitations

Given these factors, patients who had surgical procedures that required minimal or no sedation, procedures expected to alter post-operative neurologic examinations, and procedures associated with immunosuppressive therapy use that may affect MS relapse rate (e.g. organ transplants) were excluded from the study.

The investigators do point out that a MS relapse can manifest in many different ways, and there's always risk of over or underreporting when it comes to a patient's symptoms after a procedure.

"A relapse, or flare, can present as any neurologic symptom," says De Lott. "It can include weakness in an arm or leg, loss of sensation, vision loss, problems with walking or coordination … it spans the spectrum."

MORE FROM MICHIGAN: Sign up for our weekly newsletter

In this study, relapse was defined as lasting 24 hours or longer in the absence of a concurrent documented infection or fever. Both De Lott and Braley say it's not clear if it's the anesthesia or some other variable of surgery, like stress to the body, that could impact a person's relapse risk.

The investigators also point out that other factors such as age can affect relapse rate, and the study population included many older adults (mean age was 49-years-old, range 18-years old to 75-years old).  The few patients who did have post-operative relapses in the study (n=12) tended to be younger and had a higher frequency of enhancing lesions on a MRI, which Braley states may indicate more severe or active disease.

Additionally, only those procedures occurring at Michigan Medicine within a 90-day window were captured. Relapses outside that window could've been missed.

The crude estimate of the pre- and post-operative annualized relapse rates were 7.1 percent and 5.5 percent per patient per year, respectively. The odds of a post-operative relapse did not significantly differ from the odds of a pre-operative relapse even after adjusting for age and all other fixed between patient variables.

"Although a larger study is necessary to confirm our findings," Braley says, "these data suggest that surgery requiring anesthesia is not a trigger for MS relapse.  These results may allay concerns that many healthcare providers have when approaching MS patients for surgery."

Other study authors: Samantha Zerafa, research assistant at U-M's College of Engineering; Kerby Shedden, Ph.D., associate professor of Biostatistics at U-M's School of Public Health; Galit Levi Denietz, Ph.D., assistant professor in neurology; Michelle Earley, biostatistician II at George Washington University; and Benjamin Segal, M.D., professor of neurology.