Characteristics of clinical descriptive variables and polysomnographic findings of catathrenia.

Study objectives: Catathrenia has been classified as a sleep-related breathing disorder variant in the third edition of the International Classification of Sleep Disorders, but its validity remains unverified. We analyzed the clinical descriptive variables and polysomnographic findings of catathrenia and discussed the similarities and differences to those of obstructive sleep apnea (OSA), non-REM parasomnias, and sleep bruxism (SB).

Methods: A retrospective analysis was conducted on 47 patients diagnosed with nocturnal groaning through polysomnography. We examined sex, body mass index, age at symptom onset, weekly symptom frequency, and presence/absence of comorbidities, including OSA, periodic limb movement disorder, non-REM parasomnia, and SB. The groaning event (GE) index was calculated according to sleep position and sleep stage.

Results: The distribution of patients with catathrenia did not show sex difference (male/female = 20:27), body mass index was 20.6 ± 3.0 kg/m², and age of onset was 18.2 ± 7.4 years. The GE index was higher in stages N1 and R than in stage N3 and in the supine position than in the lateral position. There were no cases complicated with non-REM parasomnia, but the complication of SB was observed in 30% of the participants, and SB events appeared immediately before or during the interictal period of the GE episodes in these cases.

Conclusions: Given the clinical background, posture- and sleep stage-dependent appearance of GEs, and the relatively high complication rate of SB, catathrenia pathogenesis may be heterogeneous or comprise elements of different sleep disorders.