Delirious Mania with Mild Encephalitis and a Reversible Splenial Lesion Successfully Treated with Electroconvulsive Therapy: A Case Report.

Delirious mania is a rare but severe neuropsychiatric condition characterized by the acute onset of manic symptoms, agitation, delirium, and catatonia. It constitutes a psychiatric emergency and is often misdiagnosed as infectious or autoimmune encephalitis due to overlapping clinical features. Mild encephalitis/encephalopathy with a reversible splenial lesion (MERS) is a radiological entity typically associated with viral infections, metabolic imbalances, or neuroinflammation, presenting as an acute encephalopathic state. We report the case of a 37-year-old male with bipolar disorder who presented with acute-onset aggressive behavior, delusions, disorganized speech, and autonomic instability. Despite the initial pharmacological intervention, his symptoms persisted. Brain magnetic resonance imaging revealed a splenial lesion consistent with MERS. Given the poor response to conventional treatment, electroconvulsive therapy (ECT) was initiated, resulting in significant clinical improvement. This case illustrates the rare co-occurrence of delirious mania and MERS, emphasizing the diagnostic and therapeutic challenges posed by such presentations. It further underscores the potential utility of ECT in managing treatment-resistant delirious mania, particularly in the context of neuroinflammatory involvement. The observed clinical improvement suggest that ECT may exert therapeutic effects beyond conventional psychiatric symptom management. Although this report may help clinicians in the treatment of similar presentations, further research is warranted to elucidate the relationship between neuroinflammation and psychiatric disorders and to establish the role of ECT in similar cases.