Which static factors are involved in the pathogenesis of obstructive sleep apnea (OSA)?

Updated: Sep 15, 2020
  • Author: Himanshu Wickramasinghe, MD, MBBS; Chief Editor: Zab Mosenifar, MD, FACP, FCCP  more...
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Both static factors and dynamic factors are involved in the development of OSA. Static factors include surface adhesive forces, neck and jaw posture, tracheal tug, and gravity. Any anatomic feature that decreases the size of the pharynx (eg, retrognathia) increases the likelihood of OSA. Gravitational forces are felt simply by tilting one’s head back to where the retroposition of the tongue and soft palate reduce the pharyngeal space. For most patients, OSA worsens in the supine sleeping position.

An important static factor that has been found is the reduced diameter of the pharyngeal airway in wakefulness in OSA patients compared with non-OSA patients. In the absence of craniofacial abnormalities, the soft palate, tongue, parapharyngeal fat pads, and lateral pharyngeal walls are enlarged in OSA patients versus non-OSA patients.

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