Abstract
Case A 33-year-old woman presented with three witnessed tonic-clonic seizures preceded by headache and vomiting. Intravenous (IV) levetiracetam 2gm, dexamethasone, ceftriaxone and acyclovir were given empirically. She was afebrile with no signs of meningism and could not follow multistage commands. The MRI brain demonstrated multifocal T2/FLAIR enhancing lesions. Highly frequent multifocal epileptiform abnormalities maximal in right posterior quadrant with electrographic seizures were captured on EEG. An FDG-PET revealed a mediastinal mass adjacent to right atrium with high uptake. The serum anti-GAD(>2000) and anti-Hu antibodies returned positive. The cerebrospinal fluid examination was normal. The patient was managed as limbic encephalitis with multiple antiseizure medications (ASMs) clobazam, lacosamide, phenytoin and levetiracetam,pulsed IV methylprednisolone followed by IV immunoglobulins and Rituximab. The mediastinal mass was resected, and the histopathology demonstrated lymphocyte-rich thymoma.
Due to ongoing focal-seizures, she required induced coma with propofol and midazolam. Continuous-EEG monitoring was consistent with super-refractory status epilepticus. Thiopentone infusion was titrated to burst suppression and ASMs escalated (valproate, phenobarbital, topiramate and perampanel) in addition to plasma exchange. In discussion with immunology, cyclophosphamide induction commenced. She was seizure-free on day 4 intensive care (ICU) admission. Anaesthesia and ASMs were gradually weaned. She was discharged following 41-day ICU admission and 3-month inpatient stay. She remains seizure-free 18 months since admission.
Discussion Thymoma can present with paraneoplastic neurological syndromes. There is no clear evidence that anti-GAD/anti-Hu antibodies are pathogenic in the associated syndrome. The case highlights the importance of aggressive multimodal immunotherapy in the setting of super-refractory status epilepticus of autoimmune aetiology.
