Teaching NeuroImage: Hyperglycemia-Induced Occipital Lobe Seizures

Abstract

A 64-year-old man was admitted with right-sided headache and confusion. He experienced episodes of left-sided flashing lights evolving to left-beating nystagmus with impaired awareness, suggesting right occipital lobe-onset seizures, for which levetiracetam was prescribed. Between episodes, he had left homonymous hemianopia. Brain MRI showed right occipital lobe swelling with cortical T2-fluid-attenuated inversion recovery (FLAIR) hyperintensity and diffusion restriction (Figure). Blood glucose on admission was 21.8 mmol/L (normal: 3.4-11 mmol/L) and HbA1C was 12.8%, indicating a new diagnosis of diabetes mellitus and raising concern for hyperglycemia-induced occipital lobe seizures.1,2 Testing for alternative etiologies including CSF bacterial culture, viral PCRs, cytology, and autoimmune encephalitis antibodies, as well as serum anti-myelin oligodendrocyte glycoprotein (MOG), was negative. After blood glucose normalization, his symptoms resolved. Repeat brain MRI 8 weeks later was unremarkable (Figure). Occipital lobe seizures are a rare but characteristic manifestation of hyperglycemia. Glycemic control generally results in their resolution, emphasizing the importance of prompt diagnosis.1,2