Conference Coverage

What Is the Prevalence of Truly Benign MS?

The existence of benign MS is controversial, and patients with normal function in all domains are rare.


PARIS—Benign multiple sclerosis (MS) appears to be rare. Its estimated prevalence is less than 4%, according to a study described at the Seventh Joint ECTRIMS–ACTRIMS Meeting.

The existence of benign MS has been proposed, but it remains controversial. Neurologists are uncertain about the frequency and pathologic explanation for a favorable outcome in MS. Identifying and studying individuals with benign MS would have “considerable implications for patient management and for our understanding of the biology of the disease,” said Emma Tallantyre, BMBS, PhD, Clinical Senior Lecturer in the Division of Psychological Medicine and Clinical Neurosciences at Cardiff University in the United Kingdom, and colleagues.

Emma Tallantyre, BMBS, PhD

Most definitions of benign MS are focused on walking ability after 10 or 15 years, despite the far wider effects of MS on ability. Dr. Tallantyre and colleagues screened a prevalent population of more than 2,000 people with MS and found 275 individuals who had unlimited walking ability after 15 or more years from onset. The investigators undertook detailed assessments of 56 of the individuals within this group (ie, those recorded to have unlimited walking ability after the longest disease durations). Assessment incorporated scores of cognition, fatigue, mood, vision, bladder symptoms, and arm and leg function.

All patients were considered to have relapsing-remitting MS, but they showed a wide range of relapse frequency and severity. In a group of 32 patients who fulfilled a contemporary definition of benign MS based on the Expanded Disability Status Scale, the researchers considered less than 25% to be truly benign, which was defined as having normal function in all domains. Patient-reported scores of MS impact correlated strongly with the outcomes of clinical assessment, but patients’ own perceptions of their condition was more benign than clinicians’ perceptions.

MR imaging was used to explore the biology underlying benign MS using a global approach and a tract-based approach. The study provides early insights into the phenotypic and imaging characteristics of benign MS and could provide information about the biologic mechanisms of a favorable outcome in MS, said Dr. Tallantyre.

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