Multiple sclerosis with atypical MRI presentation: Results of a nationwide multicenter study in 57 consecutive cases.

Background: The recent 2017 modification have increased the sensitivity of McDonald criteria for MS. Nevertheless, some MS patients with atypical MRI findings have been identified, leading to prolonged delay to diagnosis and high costs to look for alternative diagnoses.

Objective: To describe a series of MS patients with atypical MRI presentation.

Material And Methods: Patients with atypical MS were identified through a nationwide retrospective study. We established a five groups classification: tumefactive demyelinating lesion (TDL)-onset MS, acute disseminated encephalomyelitis (ADEM)-like MS, cavitary MS and leukodystrophy-like MS. All the patients meeting our radiological criteria for atypical MS were included.

Results: A total of 57 patients met the inclusion criteria. 7 cases were classified in the TDL-onset group, 10 in the ADEM-like group, 26 in the cavitary group and 14 in the leukodystrophy-like group. Overall risk of conversion to MS after an isolated TDL was around 30% at five years. Patients in the TDL-onset and ADEM-like groups globally presented an acute onset and a relapsing-remitting evolution. Conversely, patients in the cavitary and leukodystrophy- groups largely evolved with a progressive and severe course.

Conclusion: A significant number of MS patients can have a striking atypical presentation and may be misdiagnosed. This preliminary analysis helps to refine the spectrum of atypical MS patients.