Functional Coma: Two Case Reports and a Review of the Literature

Background: Psychiatric illness can mimic a comatose state. The most common is a conversion reaction resulting in a functional coma, which poses a unique diagnostic challenge to the clinician. Little is known about this condition, and the literature is limited by inconsistent terminology and by a lack of high-quality evidence. Objective: To provide a conceptual definition of functional coma, describe case examples, summarize management, and increase recognition of this often underacknowledged entity. Methods: We present two cases and provide a comprehensive review of the literature on the differential diagnosis, pathophysiology, workup, and management. Results: Functional coma is defined as an involuntary coma-like state that occurs in the absence of structural or metabolic damage to the brain and that is distinct from catatonia. This term should supplant the previous phrase of “psychogenic coma.” Psychiatric disorders are frequently present premorbidly, but are not required for the diagnosis. About half of the cases occur in the perioperative setting. Physical exam can provide helpful clues, including passive resistance to eye opening or avoidance of the face with arm drop. Additional work-up, including laboratory studies, brain imaging, and electroencephalography, should be obtained but are unremarkable in functional coma. Case studies suggest that the episodes last for several hours, with a range of 45 minutes to 4 days. Treatment includes supportive management and careful psychoeducation. Conclusions: Functional coma should be conceptualized as a distinct condition from catatonia and psychogenic non-epileptic seizures. Additional clinical and translation research is needed to further explore the etiology of this condition.