Long-term persistence of NMDAR antibodies after encephalitis with de novo occurrence of demyelinating disorder.

The issue of persistence of NMDAR antibodies after encephalitis is not fully elucidated and their relationship with demyelinating disorders has been suggested. A female patient showed at the age of 18 an acute neurological disorder (with psychiatric symptoms, focal seizures, orofacial dyskinesias and hypoventilation requiring ventilatory support) clinically mimicking anti-NMDAR encephalitis. At that time specific laboratory tests were not available, CSF revealed oligoclonal bands and MRI was negative. The patient had full recovery after first line immunotherapy (i.v. steroids and immunoglobulins). Fifteen years later, at the age of 33, she was hospitalized with subacute right hemiparesis and MRI disclosed multiple T2 hyperintensities in the white matter, one of them in the left midbrain showing contrast enhancement. Serum and CSF NMDAR antibodies were positive while MOG and AQP4 antibodies were negative. Intravenous methylprednisolone led to complete recovery. This case report provides evidence of a long-term persistence of NMDAR antibodies even 15 years after the encephalitis and raises the suspicion of a possible causal relationship between NMDAR antibodies and demyelinating disorders in the form of multiple sclerosis.