Obstructive Sleep Apnea and Role of the Diaphragm

Abstract

Obstructive sleep apnea (OSA) causes multiple local and systemic pathophysiological consequences, which lead to an increase in morbidity and mortality in patients suffering from this disorder. OSA presents with various nocturnal events of apnoeas or hypopneas and with sub-clinical airflow limitations during wakefulness. OSA involves a large percentage of the population, particularly men, but the estimate of OSA patients could be much broader than data from the literature. Most of the research carried out in the muscle field is to understand the causes of the presence of chronic nocturnal desaturation and focus on the genioglossus muscle and other muscles related to dilating the upper airways. Sparse research has been published regarding the diaphragm muscle, which is the main muscle structure to insufflate air into the airways. The article reviews the functional anatomy of the muscles used to open the upper respiratory tract and the non-physiological adaptation that follows in the presence of OSA, as well as the functional anatomy and pathological adaptive aspects of the diaphragm muscle. The intent of the text is to highlight the disparity of clinical interest between the dilator muscles and the diaphragm, trying to stimulate a broader approach to patient evaluation.

Proposal for Manual Osteopathic Treatment of the Phrenic Nerve

“…Phrenic dysfunction could cause functional alterations of the lingual complex and related symptoms, such as dysphagia and sleep apnea, probably due to neurological relationships with the cranial nerves that innervate the tongue area, as previously described [ 27 , 89 , 91 , 110 , 111 ]. A dysfunction of the phrenic nerve could increase blood pressure, thanks to the connection with the sympathetic system, increasing sympathetic neural outflow [ 16 ].…”

“…In animal models, we know that mild inflammation is sufficient to reduce the function of the phrenic nerve [ 87 ]. Let us remember that the presence of a sub-clinical inflammatory environment can lead to the formation of scars between the different tissues, and a phrenic dysfunction cannot always cause symptoms that can easily be linked to the nerve [ 88 , 89 ]. In the absence of known causes, the phrenic nerve can undergo functional alterations (idiopathic).…”

“…Symptoms of phrenic dysfunction are not necessarily linked to dyspnea at rest or on exertion but can present as non-specific neck pain or low back pain, alterations in shoulder mobility, mood alterations, a decrease in the pain threshold, alteration of neuro-coordination, and more [ 27 , 89 - 95 ].…”

Hyoid Bone Syndrome in a Patient Undergoing Left Ventricular Assist Device Implantation

“…The middle pharyngeal constrictor muscle is managed by a central pattern generator (CPG), through complex neural connections between the spinal cord and the brain stem; CPG controls the functions of all peri-hyoid muscles [ 30 ]. The glossopharyngeal nerve (IX cranial nerve) innervates the middle pharyngeal constrictor muscle and sends parasympathetic fibers to the stylohyoid ligament [ 31 ].…”

“…We can hypothesize that persistent dysfunction of the diaphragm muscle could alter the function of the vagus nerve, negatively affecting the functionality of the pharyngeal area and tongue, and creating abnormal tensions suffered by the hyoid bone [ 30 ]. Muscular and ligamentous tensions of the hyoid bone could create non-physiological mechano-metabolic conditions, and this information could be transported in a nociceptive manner [ 32 ].…”