Differential Diagnosis in Late Onset Multiple Sclerosis (P1.2-060)

Objective: To identify clinical-radiological characteristics of patients consulting with suspected Late Onset Multiple Sclerosis (LOMS).

Background: LOMS is defined by clinical presentation after 50 years of age, being less than 12% of MS population. Diagnosis is challenging considering the broad spectrum of differential diagnoses proposed for white matter lesions in this subgroup of patients; thus, misdiagnosis is frequent. Finally, there is scarce evidence about prognosis and treatment of these patients.

Design/Methods: Patients presenting first symptoms after 50 years of age, consulting in a tertiary neurological center in Buenos Aires, Argentina, from January/2011 to September/2018 referred with previous diagnosis of MS, white matter lesions or demyelinating disorders, were included. Demographic, clinical MRI and oligoclonal-bands (OCB) characteristics were analyzed with parametric and non-parametric tests.

Results: We included 153 patients with late onset symptoms: 85 were MS and 67 had other differential diagnosis. The most frequent diagnosis was demyelinating disorders not MS or NMOSD (n=30), followed by microvascular damage due to unspecific white matter lesions (n=25).

26 patients (36%) were previously misdiagnosed with MS diagnosis (not fulfilling MS criteria) and 7 patients were already on disease modifying drugs. The cost of mistreated patients was estimated in USD 7.184.200.

Among the patients who met criteria for the diagnosis of LOMS myelitis was the most frequent presentation (37%).

On MRI analysis, corpus callosum lesions and periventricular demyelinating plaques (“Dawsonfinger signs supported MS diagnosis”) were the only specific findings bringing statistically significant information to differentiate MS from other diagnosis. Positive OCB were useful to differentiate demyelinating disorders from non-demyelinating etiologies.

Conclusions: LOMS diagnosis is challenging, being necessary a detailed clinical history, physical exam and MRI description, in order to avoid misdiagnosis and unnecessary treatment.

This is the largest LOMS specific case series from Latin-America, bringing important information about this subgroup of patients, applicability of MS diagnostic criteria and differential diagnosis.

Disclosure: Dr. Yorio has nothing to disclose. Dr. Marrodan has nothing to disclose. Dr. Farez has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with TEVA, Merck-Serono, Biogen-Idec, and Novartis. Dr. Correale has received personal compensation for consulting, serving on a scientific advisory board, speaking, or other activities with Biogen Argentina, Teva Argentina, Novartis Argentina and MERCK Argentina, and Merck/Serono Argentina and Novartis Argentina.