Acoustic characteristic of catathrenia and snoring: different subtypes of catathrenia

Catathrenia (nocturnal groaning) is a rare condition characterized by monotonous irregular sounds that occur during sleep. Not infrequently, catathrenia has been confused with expiratory snoring. We aimed to clarify the subtypes of catathrenia and differentiate them from snoring using sound analyses.

We enrolled five patients with catathrenia who were confirmed by overnight polysomnography (PSG). They underwent clinical and physical evaluation, including craniofacial and oromandibular examination, and fulfilled sleep-related questionnaires. Catathrenia and snoring of patients were analyzed acoustically with a Multi-Dimensional Voice Program.

All subjects were young (mean 31.0 years, 22-39) and slim (mean 20.5 kg/m(2) body mass index) women. PSG findings showed normal ranged apnea-hypopnea indices (mean 0.8±1.4/h), respiratory disturbance indices (2.6±1.7/h), and well-preserved sleep architecture. The number of catathrenia during PSG varied between one and 55 per patient, with sound duration ranging from 0.3 to 15.1 s. Of a total of 113 episodes, 70 (61.9%) occurred during REM sleep and 43 (38.1%) during NREM sleep. All patients showed light snoring through the PSG night. In the sound analysis three patients demonstrated monotonous sinusoidal catathrenia sounds, which were of normal ranged fundamental frequency. The other two had sawtooth-shaped catathrenia signals with higher fundamental frequency. In contrast, snoring had an irregular signal in all patients.

We observed that catathrenia had morphologic regularity, with two types of sound pitches, and snoring had a different signal from catathrenia by sound analysis.