Dementia Revealing Multiple Sclerosis

Cognitive abnormalities are frequently observed in advanced stages of Multiple Sclerosis (MS). Their frequency increases from clinically isolated syndromes, to relapsing-remitting and secondary progressive MS. The most frequently impaired functions are information processing speed, attention and memory. Dementia is uncommon but may reveal a MS. We reported a 47-year-old woman suffering since 8 months of headache with a progressive amnesia, temporospatial disorientation and behavioral disorders. On examination, we found dementia syndrome and a frontal syndrome. Brain MRI showed a T2 hyperintensity multifocal ovoid lesions with enhancement in the periventricular white matter and in the corpus callosum. Diagnostic hypotheses were ADEM or MS. Isoelectric focusing revealed oligoclonal bands and elevated IgG index. She was treated with intravenous methylprednisolone 1 g daily for five consecutive days. There was a regression of the symptomatology but 4 months after diagnosis, the patient presented with a postural instability, gait difficulty, terminal intention tremor and dysmetria. A diagnosis MS was considered and she was given interferon. The concept of MS being a dementing illness is not novel. Neurologists are well aware that patients with MS may present with cognitive impairment. But the fact that this disease is revealed by dementia is rare and new.