Electroconvulsive Therapy in Seronegative Paraneoplastic Encephalitis With Catatonia

Autoimmune encephalitis frequently presents with prominent psychiatric symptoms and may mimic primary psychiatric disorders, particularly in the early stages. We report the case of a 38-year-old man who presented with a 2-week history of behavioral disturbance, persecutory ideation, auditory hallucinations, and fluctuating disorganization of thought and behavior, without prior psychiatric history. During hospitalization, the clinical picture evolved to include psychomotor retardation and prominent catatonic features. Given the subacute onset and atypical presentation, autoimmune encephalitis was suspected. Cancer screening identified a mixed testicular germ cell tumor, and right orchiectomy was performed. Despite tumor removal and immunotherapy, the patient showed no meaningful clinical improvement and progressed to severe catatonia. Pharmacological treatment with benzodiazepines and antipsychotic medications was ineffective. Electroconvulsive therapy was therefore initiated. After 12 bitemporal electroconvulsive therapy sessions, a marked and sustained clinical improvement was observed, with progressive resolution of catatonic, psychotic, and behavioral symptoms. This case highlights that severe catatonia may represent the dominant psychiatric manifestation of seronegative paraneoplastic encephalitis and suggests that electroconvulsive therapy may be an effective therapeutic option for refractory catatonia in this context.