Catathrenia is a rare sleep-related breathing disorder characterized by prolonged expiratory groaning. It is often underrecognized and can be misinterpreted as obstructive sleep apnoea (OSA), central sleep apnoea (CSA), or a parasomnia. Accurate identification of its clinical and polysomnographic features is necessary to avoid misdiagnosis and to guide management decisions.
This report presents a retrospective observational review of adult patients diagnosed with catathrenia at the Serviço de Medicina do Sono de Coimbra. Diagnosis required attended overnight polysomnography (PSG) with synchronized audio-video recording. The investigators collected demographic data, presenting symptoms, documented comorbidities, PSG variables, treatment modalities, and clinical outcomes from the medical records.
Catathrenia events were operationally defined in the study as a pattern of deep inhalation followed by prolonged exhalation producing monotonous groaning, confirmed on synchronized audio-video PSG recordings.
Ten patients fulfilled the diagnostic criteria for catathrenia and were included in the analysis. The median age was 46 years, with a reported range from 27 to 78 years. The cohort was predominantly female, comprising 70% of cases.
Reported comorbid conditions included obesity in four patients, depression in two patients, Parkinson's disease in one patient, and restless legs syndrome in one patient. These comorbidities were recorded from the clinical histories available in the retrospective chart review.
All catathrenia episodes identified in this series occurred exclusively during REM sleep, a finding emphasized by the authors as a distinguishing feature. Events were visually and audibly confirmed on PSG as the defined sequence of deep inspiration followed by a prolonged, monotonous expiratory groan. Seven patients in the series had excessive daytime sleepiness, defined as an Epworth Sleepiness Scale score greater than 10.
Six of the ten patients (60%) had coexisting obstructive sleep apnoea (OSA) documented on PSG. The presence of OSA highlights the potential for diagnostic confusion and the importance of audio-video correlation to differentiate catathrenia from apnoeic events or parasomnias.
The most frequently used therapeutic modality in this cohort was continuous positive airway pressure (CPAP). CPAP therapy was associated with objective or subjective improvement in most patients who received it, according to the retrospective outcome data reported.
In addition to CPAP-treated cases, two patients in the series experienced spontaneous remission of catathrenia without active intervention. The report does not provide detailed longitudinal follow-up durations or standardized outcome measures beyond the statement that CPAP was linked to improvement and that spontaneous remission occurred in two individuals.
The authors underscore that catathrenia remains underdiagnosed and can mimic other sleep disorders, particularly OSA, CSA, and parasomnias. The REM-sleep predominance of events on PSG and the characteristic audio pattern (deep inhalation followed by prolonged expiratory groaning) are key diagnostic clues that may reduce misclassification.
Individualized management is recommended, and the case series suggests that PAP therapy, most commonly CPAP, can reduce symptoms in many patients. The observation of spontaneous remission in a subset of patients indicates variable natural history and supports a case-by-case approach to treatment decisions.
As a retrospective observational series from a single tertiary sleep service, the report is limited by small sample size and the constraints inherent to chart review. Specific details such as standardized severity measures, objective long-term outcome data, and precise CPAP settings or adherence data were not reported in the abstract. Because the full dataset is not presented here, additional methodological limitations cannot be further detailed from the source abstract.
In this real-world series of ten adults with catathrenia diagnosed by attended PSG with synchronized audio-video, the condition was predominantly observed in middle-aged adults and females, commonly co-occurred with OSA, and manifested exclusively during REM sleep. CPAP therapy was the most used treatment and correlated with symptomatic improvement in most treated patients, while spontaneous remission occurred in two cases. The authors emphasize the need for recognition of PSG and clinical features to avoid misdiagnosis and to guide individualized management.