A group of experts in MS imaging have published new information on imaging and clinical findings that might help explain why some people experience a mild course of multiple sclerosis, also known as “benign” MS. They recommend that cognitive functions, not just physical functions, be taken into account when labeling a person’s MS as benign. Massimo Filippi, MD (Scientific Institute and University Ospedale San Raffaele, Milan, Italy) and colleagues in the European imaging collaboration known as “MAGNIMS” (Magnetic Resonance Research in MS) report their findings in Neurology 2009;72:1693-1701.
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Background: MS is notoriously unpredictable in its course. Some people experience a benign course of MS, which generally refers to individuals who have had MS for 15 to 20 years but whose physical disability continues to be very mild. There currently is no way to predict whether a person’s future course of MS will be benign, and not all individuals who have an initially benign course stay that way.
Finding a way to reliably predict who will have a mild course of MS would allow doctors to give better advice to their patients, and possibly spare some individuals from the expense and inconvenience of taking an MS therapy early in the course of their disease, which is considered advisable for most who have relapsing-remitting MS. Studies to understand benign MS are also aimed at identifying factors responsible for preserving these individuals’ functions, which may be translatable to improving therapy for people who experience more disabling MS.
The Report: This article reports the conclusions of a MAGNIMS workshop held in May 2008, during which this group of imaging experts reviewed the main MRI (magnetic resonance imaging) studies that have been conducted in people with benign courses of MS. Studies that compared people with more typical disease courses, such as relapsing-remitting MS (involving attacks or relapses, followed by partial or complete recovery periods) and secondary-progressive MS (which starts as a relapsing-remitting course before the disease worsens more steadily, with or without occasional flare-ups) yielded few MRI findings that were consistently unique to people with benign MS, or that could be used as early predictors of a milder course.
However, generally they found indications that people identified as having a benign course of MS more frequently had fewer lesions (areas of tissue damage or disease activity) compared to people with relapsing-remitting MS in specific areas of the brain critical to movement, such as the upper cervical cord and the cerebellum. Furthermore, people with benign MS demonstrated milder inflammatory activity and less atrophy (loss of tissue volume) in brain regions relevant to clinical disability, including the cerebellum, spine, and gray matter (the area of the brain where nerve cell bodies are located) compared to people with secondary-progressive MS. They also had less severe tissue damage in lesions and in the gray matter than in people with secondary-progressive MS.
The authors caution that these signs are not predictive, and should not be used as criteria for establishing a diagnosis of benign MS. However, these MRI abnormalities in someone with seemingly benign MS serve as potential red flags pointing to another course of MS. They recommend that studies of large cohorts of people classified as having benign MS are warranted to validate these findings. The investigators suggest that one or more of these factors, along with the ability of the brain to compensate for damage by using other regions of the brain, may account for the milder course in people with benign MS.
Importantly, the MAGNIMS collaborators also discussed cognitive impairment, which has been reported in as many as 45% of people with otherwise benign courses of MS, and that more MRI abnormalities did occur in those labelled benign who experienced cognitive problems. The group urges, “We believe that a new definition of [benign] MS is needed” which would include the absence of cognitive impairment as assessed by a neuropsychological evaluation.
National Research and Programs
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With information from the National MS Society (US)
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