IMPACT OF NECK DISSECTION TYPE ON SHOULDER RANGE OF MOTION IN ORAL SQUAMOUS CELL CARCINOMA PATIENTS: ANATOMICAL BASIS, COMPARATIVE FUNCTIONAL OUTCOMES AND STRATEGIES FOR PREVENTION

Abstract

Background: Shoulder morbidity following neck dissection (ND) for oral squamous cell carcinoma (OSCC) is principally attributable to injury to the spinal accessory nerve (SAN). The extent of dissection is the primary determinant of functional outcome, yet objective, longitudinal goniometric data comparing modified radical neck dissection (MRND), supraomohyoid neck dissection (SOHND), and extended supraomohyoid neck dissection (ESOHND) through the adjuvant radiotherapy period remain limited. Aim: To prospectively evaluate and compare shoulder range of motion (ROM) across MRND, SOHND, and ESOHND at defined perioperative and post-radiotherapy intervals, and to establish normative ROM values in a healthy control population. Materials and Methods: A prospective study was conducted at Gurunanak Institute of Dental Sciences and Research, Kolkata (2023–2024). Six biopsy-proven OSCC patients (9 shoulders: MRND=3, SOHND=2, ESOHND=4) constituted the study group. Seven bilateral ROM parameters — flexion, extension, abduction, horizontal abduction, horizontal adduction, internal rotation, and external rotation — were measured using a universal goniometer at preoperative, immediate postoperative (days 1, 2, 3, 10, 30), pre-radiotherapy, immediate post-radiotherapy, and 2- and 3-month post radiotherapy intervals. One-way ANOVA and paired t-tests were employed for statistical analysis (p<0.05). Results: MRND consistently yielded the highest mean ROM values, ESOHND the lowest, and SOHND occupied an intermediate position across all measured parameters. Statistically significant inter-group differences were confined to abduction at post-radiotherapy two months (p=0.019) and horizontal abduction at postoperative days 2 (p=0.014) and 3 (p=0.009). Internal rotation, external rotation, and horizontal adduction showed no significant inter-group differences at any time point. Conclusion: ROM deficits following neck dissection demonstrate a clear gradient inversely proportional to the extent of SAN dissection. Functional impairment persists even after nerve-sparing procedures, implicating traction injury, C2–C4 motor-contribution disruption, and radiotherapy-related fibrosis as additional mechanisms. These findings underscore the importance of anatomically meticulous surgical technique, limitation of dissection to oncologically necessary levels, and structured postoperative physiotherapy rehabilitation.