Clinical case-control study of the proprioceptive innervation of the pharynx in patients with obstructive sleep apnea

OBJECTIVE: To investigate the morphological aspects of the sensory innervation of the palatoglossus, palatopharyngeus, and superior pharyngeal constrictor muscles in a control group with normal sensory function and no obstructive sleep apnea, and a group of apneic patients. METHODS: Subjects consisted of 7 case patients with Obstructive Sleep Apnea (OSA) diagnosed by polysomnography and prior indication of pharyngeal surgery to treat obstructive sleep-disorder-related breathing, and 6 control patients with prior surgical indication of palatine tonsillectomy for the treatment of chronic tonsillitis or recurrent tonsillitis and without moderate/severe OSA. The specimens were collected in vivo through tonsillectomy in the control group and lateral pharyngoplasty in the case group. Histomorphometry of nerve endings was assessed using hematoxylin-eosin staining in optical microscopy, and by immunofluorescence detection of nervous structures, with detailed analysis performed using confocal microscopy. RESULTS: In the control group, muscle spindles were visualized in the palatoglossus muscle, and free, and complex nerve endings were identified in all three muscles, including Meissner, Golgi, and Ruffini-like formations, as well as spiral-wharves nerve structures in the palatoglossus and superior pharyngeal constrictor muscles. In the case group, morphological abnormalities were observed in the sensory corpuscles, with a high prevalence of unclassifiable complex nerve formations, and a reduction in the perivascular plexus. Spiral-wharves nerve formations were observed in all muscles of the apneic patients. The superior pharyngeal constrictor muscle was the most affected in the case group, showing a lower variety of nerve formations. CONCLUSION: In OSA, the complex arrangement of the human pharynx is impaired, with inflammation and distortion of the nervous formations, potentially impairing the pharyngeal function and contributing to the symptoms related to this disease. LEVEL OF EVIDENCE: Level 3.