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Published on: April 18, 2015
Muscle fibre type and habitual snoring
S Smirne1, S Iannaccone, L Ferini-Strambi
1Sleep Disorders Centre, State University and Scientific Institute, Milan, Italy.
Habitual snoring, an early sign of obstructive sleep apnea (OSA), is linked to abnormal muscle fiber types in the upper airway. Specifically, habitual snorers show altered medium pharyngeal constrictor muscle (MPCM) structure, suggesting a role for muscle tone dysregulation in OSA.
Area of Science:
- Physiology
- Sleep Medicine
- Muscle Biology
Background:
- Obstructive sleep apnea (OSA) is associated with upper airway anatomical abnormalities.
- Muscle tone dysregulation is also implicated in OSA pathogenesis.
- Habitual snoring is considered an initial stage of OSA.
Purpose of the Study:
- To investigate the structural characteristics of the medium pharyngeal constrictor muscle (MPCM) in habitual snorers compared to non-snorers.
- To explore potential muscle-based mechanisms contributing to habitual snoring and OSA.
Main Methods:
- Histological analysis of MPCM fibre types (I, IIa, IIb) from 13 adult men (4 habitual snorers, 9 non-snorers).
- Comparison of MPCM fibre distribution and diameter between snorers and non-snorers.
- Assessment for myopathic or neurogenic changes.
Main Results:
- MPCM in non-snorers showed smaller fibre diameters than typical limb muscles, with a higher proportion of type I and IIa fibres and fewer type IIb fibres.
- Habitual snorers exhibited significantly abnormal MPCM fibre distribution (low type I and IIb, high type IIa) compared to non-snorers (p < 0.001).
- Type IIa fibres in habitual snorers were hypertrophic, with no evidence of myopathic or neurogenic disease.
Conclusions:
- Habitual snoring is associated with specific alterations in upper airway muscle (MPCM) fibre type distribution and hypertrophy.
- These findings suggest a potential role for muscle tone dysregulation and adaptive changes in motor neuron activity in the development of habitual snoring and OSA.
- Further research is warranted to elucidate the precise mechanisms linking motor neuron function to MPCM adaptations in snorers.
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