Catathrenia


Catathrenia is a sleep-related breathing disorder, consisting of end-inspiratory apnea and expiratory groaning during sleep. This disorder is more prevalent during REM sleep, however some studies have documented catathrenia during NREM sleep. The term catathrenia originates from the Greek kata and threnia and describes a rare condition which occurs during sleep being characterized by monotonous irregular groans also known as nocturnal groaning. Multiple studies have described nocturnal vocalisation among animals and have also reported some cases in humans, especially in patients with Parkinson's disease. The nocturnal vocalisation can be groaning, moaning, or different sounds produced while asleep, the most encountered being catathrenia and sleep talking. The duration of the groaning sound varies from two to 49 s and it is known to appear more often during expiration REM sleep than in NREM sleep. Catathrenia is distinct from both somniloquy and obstructive sleep apnea. The sound is produced during exhalation as opposed to snoring, which occurs during inhalation. It is usually not noticed by the person producing the sound but can be extremely disturbing to sleep partners. Bed partners generally report hearing the person take a deep breath, hold it, then slowly exhale; often with a high-pitched squeak or groaning sound.
Catathrenia typically, sometimes even exclusively, occurs during REM sleep, although it may also occur to a lesser degree during NREM sleep. Catathrenia begins with a deep inspiration. The person with catathrenia holds her or his breath against a closed glottis, similar to the Valsalva maneuver. Expiration can be slow and accompanied by sound caused by vibration of the vocal cords or a simple rapid exhalation with no sound. Despite a slower breathing rate, no oxygen desaturation usually occurs. Certain side effects include sore throat, fatigue, and dizziness.
There is debate about whether the cause is physical or neurological, a question that requires further study. While some speculate about a direct correlation to high anxiety and stress or the concept that catathrenia is purely psychological, there is only anecdotal evidence of either proposed cause.

Classification

Catathrenia has been defined as a parasomnia in the International Classification of Sleep Disorders Diagnostic and Coding Manual, but there is debate about its classification. Importantly, in the latest version of the International Classification of Sleep Disorders, catathrenia has been included in the category of respiratory disorders, and thus it has been removed from the parasomnia category, as it was in the second version of the manual; nevertheless, a debate about the nature and classification of the disorder, still exist.

Signs and symptoms

Because catathrenia itself is not considered life-threatening, there has been very little research done in the medical community, and many experts assume that the way to treat catathrenia is to treat the underlying sleep apnea, though there is no conclusive evidence published that catathrenia results from sleep apnea, and sleep studies show that not all people with catathrenia have been diagnosed with sleep apnea. While doctors tend to dismiss it as an inconvenience, people with catathrenia routinely describe the condition's highly negative effects on their daily lives including tiredness, low energy, dizziness and vertigo, work problems, relationship and social issues, and other physical and mental problems that could be associated with low sleep quality.

Common characteristics in reported cases

There are reported characteristics that are shared among patients with catathrenia. The main characteristics are:
There are a few other similaritiesamongst people with catathrenia that have not yet been studied properly:
It was in 1983 when the first case of catathrenia was described. The disorder is especially rare and many sleep specialists and otolaryngologists are still unfamiliar with this atypical sleep pattern. Catathrenia must be distinguished from moaning during epileptic seizures, central sleep apnea, sleep-related laryngospasm, snoring, and stridor. Since polysomnography alone is insufficient to correctly distinguish catathrenia from central sleep apnea, a video-polysomnography with audio recording is necessary to diagnose catathrenia and avoid mistakes. Despite the fact that the incidence of catathrenia might be underestimated due to misdiagnoses, an institution in Norway has found an incidence of 4 out of 1,004 among patients with sleep and/or wake problems over a 1-year period. A previous study in Japan found an incidence of 25 out of 15,052 among patients with sleep and/or wake problems over a 10-year period.

Management

Sleeping in a more upright position seems to lessen catathrenia. Performing regular aerobic exercise, where steady breathing is necessary may lessen catathrenia. Strength exercise, on the other hand, may worsen catathrenia because of the tendency to hold one's breath while exercising. Yoga and/or meditation focused on steady and regular breathing may lessen catathrenia.
Some evidence indicate that continuous positive airway pressure can be an effective treatment for catathrenia: in a study, the subject using CPAP significantly decreased the sounds typically produced because of the disorder, which almost disappeared.