Homonymous hemianopia in nonketotic hyperglycemia is an ictal phenomenon.

Extended video-EEG or 18F-fluorodeoxyglucose PET (FDG-PET) was obtained in 3 adult patients with hemianopia secondary to nonketotic hyperglycemia. Two male patients presented with left hemianopia and episodic left gaze deviation and one male patient presented with right hemianopia and visual hallucinations. None of the 3 patients had a history of seizures or known epilepsy risk factors. All 3 patients were found to have elevated serum glucose (267 mg/dL, 320 mg/dL, and 487 mg/dL) without acidosis or urine ketones. In all 3 patients, video-EEG recorded recurrent ictal discharges originating from the posterior quadrant contralateral to their hemianopia. In 2 patients, FDG-PET demonstrated corresponding focal areas of hypermetabolism. Resolution of visual symptoms was achieved with antiepileptic drugs, hydration, and tight glycemic control.