Isolated ACTH Deficiency Presenting with a Glucocorticoid-Responsive Triphasic Wave Coma

We report the case of a 58-year-old woman who presented with acutely developed coma characterized by electroencephalographic triphasic waves (TWs) in the absence of metabolic derangement. The patient's coma and TWs were promptly resolved after the administration of glucocorticoids, and thereafter isolated ACTH deficiency was diagnosed. Isolated ACTH deficiency may present with glucocorticoid-responsive acute encephalopathy without hypoglycemia, hyponatremia, or systemic hypotension. Electroencephalographic TWs or bursts of slow waves may be a clue to the diagnosis of this rare condition in patients with coma of unknown origin.