Computed tomography, magnetic resonance imaging, and electromyographic studies of tensor veli palatini muscles in patients with nasopharyngeal carcinoma.

One of the factors that induces eustachian tube dysfunction caused by the invasion of nasopharyngeal carcinoma is paralysis of the tensor veli palatini muscle. Electromyography (EMG), computed tomography (CT), and/or magnetic resonance imaging (MRI) were used to study the tensor muscle and the related paratubal structures and parapharyngeal space. This study, from 44 patients with nasopharyngeal carcinoma, showed that 67% of tensor muscles on the side of the symptomatic ear yielded abnormal electromyographic waveforms, which usually indicated a neurogenic disorder. In the majority of the abnormal EMG cases, CT or MRI often revealed that the pharyngobasilar fascia and the tensor muscle were compressed anterolaterally and the upper prestyloid parapharyngeal space was infiltrated. It was found that an abnormal electromyogram of the tensor muscle generally suggested a more advanced T stage and eustachian tube dysfunction. Otitis media with effusion in the stage I cases was usually not caused by paralysis of the tensor muscle. The invasion of some early cancers, especially localized on the torus tubarius, could also cause the effusion.