A stertor is a respiratory sound characterized by heavy snoring or gasping. It is caused by partial obstruction of airway above the level of the larynx and by vibrations of tissue of the naso-pharynx, pharynx or soft palate (this distinguishes it from stridor, which is caused by turbulent air flow below or in the larynx). It is low-pitched, non-musical, and occurs during the inspiratory phase only. In general terms it is a snoring or snuffly sound. Stertorous breathing will be audible during the post-ictal phase after a tonic-clonic seizure.
Causes of stertor are:
Loss of nervous control of the pharynx, soft palate, particularly from damage for instance by stroke or tumor to the vagus and hypoglossal cranial nerves.
Obstructive sleep apnea.
Upper airway resistance syndrome