Disease reactivation following fingolimod withdrawal in multiple sclerosis: Two case reports.

BACKGROUND: Severe multiple sclerosis reactivation following second line treatment withdrawal, defined "rebound syndrome", is becoming a prominent issue to consider when deciding to discontinue a treatment. In particular disease recurrence after cessation of fingolimod is actually poorly characterized as to date, only case reports and small case series have been described. CASE PRESENTATION: We herewith describe 2 cases of severe disease reactivation associated to a high number of brain gadolinium enhancing lesions at magnetic resonance imaging (MRI) despite high dose steroid treatment, observed a few weeks after cessation of fingolimod administration, causing a substantial and persistent worsening of patient disability that required long term hospitalization. The severity of the neurological symptom worsening and of the brain lesion largely exceeded the disease activity observed during treatment. CONCLUSIONS: Our patients developed a rebound syndrome after ceasing fingolimod treatment, defined as the development of severe neurological symptoms and multiple new or enhancing lesions exceeding previous activity. Further analysis are needed to identify patients at greatest risk of a rebound syndrome.