Persistent Delirium in the Elderly: A Case Report and Review of Multifactorial Contributors and Management Challenges.

Introduction: This case describes persistent delirium exceeding 18 months with prominent paranoid delusions in a 72-year-old woman with chronic hyponatremia, poststroke epilepsy, and alcohol use disorder. It highlights diagnostic and pharmacologic management challenges when standard agents carry prohibitive risks. Patient’s Main Concerns and Important Clinical Findings: A 72-year-old woman with a history of left hemispheric hemorrhagic stroke, poststroke epilepsy, and chronic alcohol use presented with acute confusion. Laboratory evaluation revealed severe hyponatremia (Na 122 mmol/L). Clinical findings included persecutory delusions, severe agitation with dangerous behaviors (attempting to leave moving vehicles, stabbing attempt), anxiety, insomnia, and fluctuating cognitive status with return to baseline between episodes. EEG demonstrated epileptiform discharges and generalized encephalopathy. Divalproex sodium levels at presentation were supratherapeutic (up to 127 mcg/mL). There was no evidence of prior dementia or progressive cognitive decline. Primary Diagnoses Interventions and Outcomes: The primary diagnosis was persistent delirium with multifactorial etiology. Interventions included hyponatremia correction, transition from divalproex to lacosamide, and initiation of mirtazapine, which was selected for its lower hyponatremia risk compared to other antidepressants, lower seizure risk compared to antipsychotics, and low deliriogenic potential. Sleep and anxiety improved with partial agitation reduction, though delirium persisted. Over 18 months, paranoid delusions evolved from episodic to continuous, creating treatment adherence barriers. Conclusion: This case underscores the potential for exceptionally prolonged delirium in medically complex older adults, diagnostic complexity in differentiating persistent delirium from ictal-related psychosis and other conditions, and individualized pharmacotherapy considerations. Early multidisciplinary intervention, capacity assessments, and caregiver support are critical.