Measurement of the trapezius muscle volume: A new assessment strategy of shoulder dysfunction after neck dissection for the treatment of head and neck cancers

Background The purpose of this study was to determine the actual degree of shoulder muscle change and its relation to symptoms after neck dissection for head and neck cancers. Methods Forty-two patients who underwent unilateral neck dissection were selected. Data obtained from each subject were trapezius muscle volume ratio and a Shoulder Disability Questionnaire (SDQ) score. Patients who had undergone neck dissection with spinal accessory nerve (SAN) preservation were compared with those who had received radical neck dissection. The preservation group was further separated into subgroups by the extent of neck dissection. Results Trapezius muscle volume ratio was higher and SDQ score was significantly lower in the SAN preservation group compared to the radical neck dissection group. However, the SAN preservation subgroups did not differ from each other. In addition, a good correlation between the muscle volume ratio and SDQ score was observed. Conclusion With trapezius muscle volume ratio, clinicians may be able to diagnose shoulder dysfunction after neck dissection. Further research on the subject is warranted. This suggests a novel strategy for assessing the degree of shoulder dysfunction.