Prolonged Impaired Consciousness and Periodic Sharp Wave Complexes on Electroencephalogram in an Elderly Female With Severe Lithium Intoxication.

Lithium is commonly used in bipolar disorder but carries a high risk of neurotoxicity. We present a 79-year-old female on lithium for several years who was admitted with fever and altered consciousness that was initially complicated by a urinary tract infection. Based on persistent symptoms and medical history, the patient was found to have a serum lithium level of 3.96 mEq/L (therapeutic range: 0.60-1.20 mEq/L). Despite urgent hemodialysis, her deep coma persisted for nearly two weeks after serum lithium concentration normalized. During the admission course, an electroencephalogram (EEG) revealed periodic sharp wave complexes. This case highlights the importance of maintaining a high index of suspicion for lithium toxicity in bipolar patients with altered mental status and the necessity of supportive care as clinical recovery may be delayed despite normalization of laboratory values.