Abstracts

Rationale: Autoimmune-mediated encephalopathies have significant variability in clinical phenotype on presentation. Limbic encephalitis (LE) associated with voltage-gated potassium channel (VGKC) antibodies has been described as a cause of adult onset mesial temporal lobe epilepsy (MTLE), refractory partial complex seizures, and auditory hallucinations with ictal EEG correlate. Methods: We present here a unique case of a 54-year old right-handed Caucasian female with a history of diabetes, remote Graves’ disease and rheumatoid arthritis on methotrexate and golimumab, who presented with VGKC antibody-associated new onset epilepsia partialis continua originating from the right occipital lobe, resulting in intricate complex visual hallucinations, refractory to multiple antiepileptic medications, who ultimately improved only after aggressive treatment for autoimmune encephalitis including a course of IV steroids, IVIG infusions and plasma exchange. Results: Patient’s EEG showed ictal discharges from the right occipital region that correlated with her visual hallucinations. Her brain MRI revealed unilateral temporo-parietal and occipital T2 FLAIR hyperintensities, with transiently restricted diffusion on DWI sequences, whereas in previously described cases of VGKC-associated LE MRI changes most often include T-2 signal changes in one or both temporal lobes or hippocampi and frontal lobes. Initial lumbar puncture showed 6 red blood cells, 1 nucleated cell (5% segmented neutrophils, 83% lymphocytes, 12% monocytes) and normal protein and glucose. Ultimately, multiple autoimmune antibodies were tested and VGKC antibody was found to be elevated at 249 pmol/L. In order to control her epilepsia partialis continua, patient was started on 5 antiepileptic medications, and continued to have frequent breakthrough seizures. She had good response to immunotherapy; and her repeat MRI two months later was normalized with repeat VGKC antibody.  Conclusions: To the best of our knowledge, this is the first case report of VGKC-associated encephalitis in which patient’s symptoms involve visual rather than auditory hallucinations with EEG correlate with visual symptoms. This case could provide further guidance for recognition of autoimmune encephalitis as a cause of some cases of hallucinations and perhaps increase awareness of autoimmune causes of new onset adult epilepsia partialis continua. Funding: none