Improvement of Atypical Nocturnal Vocalization Accompanied with Obstructive Sleep Apnea after Continuous Positive Airway Pressure Treatment

ABSTRACT

Catathrenia is a rare chronic disorder characterized by expiratory groaning during sleep. Neither the origin of this sound nor the pathophysiology underpinning catathrenia is understood. Although the International Classification of Sleep Disorders, 2nd edition (ICSD-2) included catathrenia among "other parasomnias," catathrenia was classified as a respiratory disorder in the 2014 ICSD-3. Several case series of this condition have been reported, but the clinical descriptions of the sound duration and intensity, usual stage of sleep at which it occurs, and treatment response differ across cases. The possibility that catathrenia is not a single disorder has also been considered. When typical catathrenia symptoms are present, but overnight polysomnography findings do not meet the typical diagnostic criteria, a diagnosis of atypical nocturnal vocalization is given. We report a case of atypical nocturnal vocalization mimicking catathrenia that accompanied obstructive sleep apnea and improved after continuous positive airway pressure therapy.