Inclusion Criteria:

• Patients being 18 years old or more referred to the sleep laboratory of a tertiary care university hospital for a baseline polysomnography for suspected OSA.

Exclusion Criteria:

• Anticoagulation (though not a contraindication for the endoscopic laryngopharyngeal sensory test, anticoagulation is an exclusion criteria for this validation study in order to keep it a minimal-risk study).
• Bleeding diathesis.
• Basal awake oxygen saturation by pulse oximetry below 88%.
• Not agree to participate in the study.
• Glasgow coma scale below of 15 (to avoid confusion with involvement of laryngopharyngeal reflexes due to neurological disease accompanied by decreased level of consciousness).
• Baseline polysomnography that does not meet validity criteria to be interpreted (according to the American Academy of Sleep Medicine).
• Baseline polysomnography performed more than 15 days before the sensory testing. Ordinarily, the sensory testing will be performed the same day or the next day of baseline polysomnography.
• More than 5% of total apnoea events being of central origin.
• History of maxillofacial or pharyngeal surgery (to avoid confusion with involvement of laryngopharyngeal reflexes due to surgery in this region).
• Laryngopharyngeal tract malignancies (to avoid confusion with involvement of laryngopharyngeal reflexes due to tumours).
• Central Nervous System (CNS) surgery in the last three months or that has left neurological sequelae (to avoid confusion with involvement of laryngopharyngeal reflexes due to sequelae of CNS surgery).
• Traumatic brain injury in the last three months or more than three month with neurological sequelae.
• History of active neuromuscular disease that affects the muscles of head and neck or with sequels present at the time of the sensory testing (to avoid confusion with involvement of laryngopharyngeal reflexes due to neuromuscular disease).
• History of cerebrovascular disease (to avoid confusion with dysphagia or sensory compromise secondary to cerebrovascular disease).
• Diabetes (to avoid confusion with diabetic neuropathy that compromises the laryngopharyngeal region).
• Chronic use of systemic corticosteroids at a dose greater or equal to 20 mg per day of prednisone or equivalent (to avoid confusion with steroid myopathy that compromises the laryngopharyngeal region).
• Upper respiratory tract infection within 15 days prior to the testing (to avoid confusion with neuropathy associated with respiratory viral disease that compromises the laryngopharyngeal region).
• Patient's inability to cooperate during the examination (to avoid measurement error caused by the lack of cooperation of the patient).