Acute Fulminant Demyelinating Disease

BACKGROUND: Acute demyelinating encephalomyelitis (ADEM) is characterized by a severe inflammatory attack, frequently secondary to infectious events or vaccinations. To date, no clear criteria exist for ADEM, and the risk of subsequent evolution to multiple sclerosis (MS) remains unknown. OBJECTIVE: To evaluate the risk of evolution to MS after a first episode of ADEM. DESIGN: Observational, retrospective case study. SETTING: Thirteen French MS centers. Patients We retrospectively studied 60 patients with ADEM who were older than 15 years with no history suggestive of an inflammatory event who presented to MS centers from January 1, 1995, through December 31, 2005. We excluded 6 patients with multiphasic ADEM because this is a rare condition and somewhat difficult to classify. After a mean follow-up of 3.1 years (range, 1-10 years), the remaining 54 patients were then classified into 2 groups: monophasic ADEM (ADEM group) (n = 35) and clinically definite MS (MS group) (n = 19). MAIN OUTCOME MEASURES: Clinical, laboratory, magnetic resonance imaging, and follow-up data were evaluated for each group. RESULTS: Patients in the ADEM group more frequently had atypical symptoms of MS (26 of 35 74%) than patients with MS (8 of 19 42%) (P = .02). Oligoclonal bands were more frequently observed in the MS group (16 of 19 84%) than in the ADEM group (7 of 35 20%) (P <.001). Patients in the ADEM group more frequently had gray matter involvement (21 of 35 60%) than those in the MS group (2 of 19 11%) (P <.001). On the basis of these results, we consider that the presence of any 2 of the following 3 criteria could be used to differentiate patients with ADEM from those with MS in our cohort: atypical clinical symptoms for MS, absence of oligoclonal bands, and gray matter involvement. On this basis, 29 of the 35 patients in the ADEM group (83%) and 18 of the 19 patients in the MS group (95%) were classified in the appropriate category. CONCLUSIONS: Our study found some differences concerning the risk of evolution to clinically definite MS after a first demyelinating episode suggestive of ADEM. These findings led us to propose criteria that should now be tested in a larger, prospective cohort study.