Voltage-Gated Potassium Channel Antibody Associated Limbic Encephalitis Presenting as a Rapidly Progressive, Refractory Status Epilepticus: A Case Report and Review of Literature (P07.177)

OBJECTIVE: To report a novel clinical presentation of limbic encephalitis associated with voltage gated potassium channel antibodies (VGKC-LE). BACKGROUND: VGKC-LE is characterized by memory impairment and psychiatric manifestations including personality, mood and behavioural changes that develop over weeks to months. Temporal lobe seizures with corresponding electroencephalographic and magnetic resonance imaging abnormalities have typically been described in patients with VGKC-LE. DESIGN/METHODS: Case report and literature review. RESULTS: A 20 year old, previously healthy male presented to the hospital with three witnessed and unprovoked generalized tonic clonic seizures. There was no preceding history of behavioral changes, psychosis, or memory difficulties. He rapidly progressed to develop generalized tonic clonic status epilepticus refractory to multiple antiepileptic medications. Eventually, intravenous propofol, midazolam and phenobarbital were used to achieve and maintain EEG-burst suppression. CSF microbiological studies were negative for viral, bacterial and fungal pathogens. He was found to have elevated serum levels of voltage-gated potassium channel antibodies (714 pmol/L). His brain MRI was normal. His EEG revealed seizure activity originating from left temporo-parietal region with secondary generalization. The patient did not respond to intravenous methylprednisolone or intravenous immunoglobulin therapy (IVIg). However, he had dramatic neurological improvement with plasmapheresis. CONCLUSIONS: This case is different from previously reported cases in that our patient presented acutely in status epilepticus and did not have any preceding clinical features of memory impairment or behavioral changes that have been described in patients with VGKC-LE. Despite refractory status epilepticus, our patient did not have the typical MRI findings often present in limbic encephalitis and did not respond to the standard immunosuppressive regimen of high dose corticosteroids and IVIg. This case adds another dimension to the spectrum of clinical presentations associated with VGKC-LE and also highlights the role of plasmapheresis in the early phase of treatment of autoimmune limbic encephalitis. Disclosure: Dr. Mann has nothing to disclose. Dr. Sekhon has nothing to disclose. Dr. Javidan has received personal compensation for activities with UCB Pharma.