Investigation of scapular muscle endurance after neck dissection in patients with headand neck cancer: a pilot study

1. IntroductionNeck dissection is an important approach for treatment of patients with head and neck cancer. However, some complications may occur during the surgery due to the anatomical location of vital structures in the neck region. One of the most common complications is spinal accessory nerve injury [1]. It causes trapezius dysfunction [2]. Altered patterns of trapezius muscle activation is associated with scapular dyskinesis [3]. Nevertheless, there is insufficient evidence due to few studies investigated trapezius muscle thickness following neck dissection in the literature.2. Research questionIs there a change in presence of scapular dyskinesis and trapezius muscle thickness after neck dissection?3. MethodsTwelve patients with head and neck cancer (5 bilateral neck dissections and 7 unilateral neck dissections) were included in the study. A total of 17 affected shoulders were evaluated preoperatively and at 3 months postoperatively. The scapular dyskinesis test defined by McClure et al. was used for assessment of scapular dyskinesis. Participants performed five repetitions bilateral, active, weighted shoulder flexion and abduction with dumbbells according to body weight (1.4 kg for body weight <68.1 kg; 2.3 kg for body weight ≥68.1 kg). Scapular movement pattern was categorized normal motion, subtle abnormality and obvious abnormality [4]. The results were recorded as “normal” for normal motion and subtle abnormality or “dyskinesis” for obvious abnormality. Trapezius muscle thickness for the upper (C6), middle (T1) and lower (T8) trapezius muscles was measured using ultrasound imaging in prone position at rest and during contraction. While the McNemar test was used to compare the presence of scapular dyskinesis before and after neck dissection, the Wilcoxon signed-rank test was used to compare trapezius muscle thickness.4. ResultsThere was no significant difference in scapular dyskinesis between patients preoperatively versus postoperatively (p = 0.250). A significant decrease was observed in both middle trapezius (p = 0.035 at resting; p = 0.003 during contraction) and lower trapezius muscle thickness (p < 0.001 at resting and during contraction) after neck dissection.5. DiscussionOur results state that presence of scapular dyskinesis may not change after neck dissection in patients with head and neck cancer. Scapular dyskinesis may appear unrelated to the surgery due to multiple factors including bony, joint and other neurologic origins except for spinal accessory nerve injury. Furthermore, results of the study support decrease of trapezius muscle thickness following neck dissection. It will be important to determine the alteration of trapezius muscle thickness in the early postoperative period in order to maintain shoulder functions of patients.FundingThis study has been funded by project 2017.KB.SAG.053, Department of Scientific Research Projects of Dokuz Eylul University.