Persistent frequent subclinical seizures and memory impairment after clinical remission in smoldering limbic encephalitis.

Abstract

Aim. To delineate a possible correlation between clinical course and EEG abnormalities in non-infectious “smoldering” limbic encephalitis. Methods. Long-term clinical data, including video-EEG monitoring records, were analysed in two patients. Results. The two patients were positive for anti-voltage-gated potassium channel complex antibody and unspecified antineuronal antibody, respectively. The latter patient had small cell lung carcinoma. Both patients had memory impairment and clinical seizures. EEG showed frequent subclinical seizure patterns in the bilateral temporal regions. Subclinical seizure patterns and memory impairment persisted over one to two years after clinical seizure remission. Therapy (prednisolone and chemoradiation in the two patients, respectively) resulted in decreased occurrence of subclinical seizure patterns and memory improvement. Conclusions. EEG seizure patterns may persist years after clinical seizure remission in “smoldering” limbic encephalitis and lead to memory impairment.