Faciobrachial dystonic seizures expressed as epileptic spasms, followed by focal seizures in anti-LGI1 encephalitis: a video-polygraphic study

Abstract

The origin of faciobrachial dystonic seizures in anti-LGI1 encephalitis is controversial due to a lack of neurophysiological characterization. We report a 68-year-old man with subacute anterograde memory loss and involuntary faciobrachial movements. Video-polygraphic recordings disclosed repetitive events characterized by sudden, short contraction of the upper limbs and ipsilateral hemiface. A focal contralateral EEG slow wave from frontal or central electrodes was accompanied by increased muscle activity, often with a diamond-shaped configuration, on the orbicularis oris muscle, deltoid muscle, and extensor muscle of the hand. This EEG/EMG pattern (resembling a tonic epileptic spasm) was always followed by oral and gestural automatisms with dystonic posturing of the upper limbs, compatible with a temporal lobe seizure. Brain MRI showed hyperintensity in the bilateral mesial temporal lobes, while 18FDG-PET revealed basal ganglia hypermetabolism with extensive cortical hypometabolism. Serum and CSF were both positive for anti-LGI antibodies. The patient was treated with intravenous methylprednisolone (1 g/day for five days) with seizure freedom within four days after initiation of the immunotherapy. In this case, a video-EEG/polygraphic study disclosed that faciobrachial dystonic seizures may resemble epileptic spasms, and the occurrence in close temporal association with focal seizures as a single ictal event is suggestive of a peculiar cortical-subcortical interaction. [Published with video sequence on www.epilepticdisorders.com].

Keywords: anti-LGI1 encephalitis; basal ganglia; epileptic spasm; faciobrachial dystonic seizure; video-EEG/polygraphy.