OBJECTIVETo study the pathologic changes of the palatopharyngeal muscles with transmission electronmicroscopy (TEM) in patients with obstructive sleep apnea hypopnea syndrome (OSAHS), the role of the above muscle in OSAHS pathogenesis was discussed.

METHODSThirty-eight palatopharyngeal muscle from OSAHS patients receiving uvulopalatopharyngoplasty (UPPP) were collected in in-patient department of Chinese Medical University and five palatal tumor patients receiving resection without snoring were chosen as the control. The palatopharyngeal muscle fiber and the feature of changes in mitochondrial morphology were observed by TEM.

RESULTSThe pathological changes were not observed in the normal control group. The muscle fibers were regularly arranged, and the mitochondrial between muscles were normal. The palatopharyngeal myofibrillar in mild OSAHS group was regularly arranged. The Z lines were straight, and most mitochondria structure were normal. In the moderate group, the myofibrillar was disorganized, and the Z lines were shortened or distorted. The myofibrillar in severe group was disorganized, similar to point-like or flake, and the Z lines and the structures of sarcomeres were disappeared. And organelle were disintegrated and mitochondria were disappeared similar to flocculent. There existed obvious fatty infiltration in the palatopharyngeal muscle. In the control, mild, moderate and severe group, pharyngeal muscle fiber disarrangement of the occurrence rate was 0, 2/10, 8/13, 14/15, the occurrence rate of mitochondrial degeneration was 0, 2/10, 8/13, 14/15, increased with the severity of the ultrastructural changes in the trend of increasing incidence.

CONCLUSIONSThe degree of OSAHS is correlated with the pathological changes of palatopharyngeal muscles. Incidence of myopathy is an important part of OSAHS secondary to chronic intermittent hypoxia in OSAHS and other pathological lesions, but also an important reason for increasing pharyngeal collapse.