Cancer-related radiation injury of tensor veli palatine and its contribution to otitis media with effusion: insights from a tree shrew model

Nasopharyngeal carcinoma (NPC) is commonly treated with intensity-modulated radiation therapy (IMRT), which, despite its effectiveness, causes off-target radiation injury to surrounding tissues, leading to complications such as otitis media with effusion (OME). OME, a chronic condition characterized by fluid accumulation in the middle ear, is one of the most common complications following radiotherapy for NPC. The tensor veli palatine (TVP), a muscle essential for the function of the Eustachian tube, is believed to be critical in the development of OME after radiotherapy. However, the mechanistic relationship between TVP injury and OME remains unclear, prompting the need for an animal model to investigate this process. 20 animals were divided into control group ( n = 10) and experimental group ( n = 10). Examinations by Micro-CT and surgical operation microscopy were executed; H&E and Sirius red staining to identify TVP pathological changes; ultrastructural was characterized by TEM; SOD and MDA were analyzed by TBA; IHC analyzed expressions of TGF-β1 and MMP-9. There was a yellowish jelly-like secretion in the auditory vesicles after radiotherapy. Micro-CT examined five tree shrews, and the presence of an effusion sign could be seen. Compared with the control group, myofiber injury and fibrosis of TVP were significant after radiotherapy ( p < 0.001), TGF-β1 ( p < 0.001), and MMP-9 ( p < 0.01) expression increased significantly, SOD activity decreased ( p < 0.01), and MDA content increased in muscle homogenate ( p < 0.001). By exposing the TVP muscle area to radiation, a tree shrew model of radiation-induced injury of TVP was established, and OME was observed, suggesting that radiation-induced fibrosis of TVP may be one of the causes of OME after radiotherapy for NPC.