A new study published in BMC Neurology found that sleep apnea is common in myasthenia gravis (MG), and respiratory patterns during sleep may differ depending on antibody subtype.
Researchers conducted overnight sleep studies in 27 participants, including nine people with acetylcholine receptor antibody-positive MG (AChR-MG), nine with muscle-specific tyrosine kinase antibody-positive MG (MuSK-MG) and nine healthy controls. All participants underwent a full sleep study followed by a daytime sleepiness test, along with validated sleep questionnaires and clinical MG assessments.
Testing detected obstructive sleep apnea in 89% of people with AChR-MG and 78% of those with MuSK-MG, compared with 34% of healthy controls. Both MG groups had significantly higher apnea–hypopnea index scores than controls, indicating more frequent breathing interruptions during sleep.
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Although the overall severity of sleep apnea was similar between the two MG groups, the researchers identified distinct patterns in when breathing disruptions occurred. In AChR-MG, respiratory events were more likely to happen during rapid eye movement (REM) sleep, the stage associated with muscle relaxation. In contrast, participants with MuSK-MG experienced more breathing disturbances during non-REM sleep and when lying on their back.
These differences may reflect the unique ways the disease affects muscles. AChR-MG is often linked to fluctuating weakness in the muscles involved in breathing, which can worsen during REM sleep. MuSK-MG, on the other hand, is associated with more persistent involvement of bulbar and axial muscles, which may predispose these individuals to position-related or non-REM sleep breathing difficulties.
Importantly, many participants diagnosed with sleep apnea did not report significant sleep complaints, highlighting the possibility that sleep-related breathing problems in MG may go unnoticed without formal testing.
The researchers say their findings underscore the importance of routine sleep evaluation in MG, even in clinically stable patients. Identifying subtype-specific breathing patterns could also help guide practical treatment advice. For example, individuals with MuSK-MG might benefit from side sleeping or using specialized pillows to optimize sleep posture.
“These observations suggest that antibody-specific neuromuscular involvement may influence nocturnal respiratory physiology in MG,” the study’s authors concluded. “Recognizing these patterns may help guide more individualized sleep evaluation and management strategies in patients with myasthenia gravis.”
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