Differential changes in muscle composition exist in traumatic and nontraumatic neck pain.

STUDY DESIGN: A population based cross-sectional study. OBJECTIVE: To clarify relative constituents of viable muscle in 2-dimensional cross-sectional area (CSA) measures of ventral and dorsal cervical muscles in patients with chronic whiplash-associated disorders (WAD), idiopathic neck pain, and healthy controls. SUMMARY OF BACKGROUND DATA: Previous data using T1-weighted magnetic resonance image demonstrated large amounts of neck muscle fat infiltration and increased neck muscle CSA in patients with chronic WAD but not in idiopathic neck pain or healthy controls. METHODS: Magnetic resonance images were obtained for 14 cervical muscle regions in 136 females, including 79 with chronic whiplash, 23 with chronic idiopathic neck pain, and 34 healthy controls. RESULTS: Without fat removed, relative CSA of 7 of 14 muscle regions in the participants with chronic WAD was larger, 3 of 14 smaller and 4 of 14 similar to healthy individuals. When T1-weighted signal representing the lipid content of these muscles was removed, 8 of 14 relative muscle CSA in patients with whiplash were similar, 5 of 14 were smaller and only 1 of 14 was larger than those observed in healthy controls. Removal of fat from the relative CSA measurement did not alter findings between participants with idiopathic neck pain and healthy controls. CONCLUSION: These findings clarify that previous reports of increased relative CSA in patients with chronic whiplash represent cervical muscle pseudohypertrophy. Relative muscle CSA measures reveal atrophy in several muscles in both patients with WAD and idiopathic neck pain, which supports inclusion of muscle conditioning in the total management of these patients. LEVEL OF EVIDENCE: 3.

Magnetic resonance imaging changes in the size and shape of the oropharynx following acute whiplash injury.

STUDY DESIGN: Prospective longitudinal. OBJECTIVE: To quantify the temporal development of magnetic resonance imaging changes in oropharyngeal morphometry in subjects with varying levels of disability following a whiplash injury. BACKGROUND: A recent cross-sectional investigation has identified reductions in the size and shape of the oropharynx in subjects with chronic whiplash-related disability when compared to healthy controls. The temporal development of such changes and their relationship to persistent disability have yet to be investigated. METHODS: Forty-one subjects (30 women) with acute whiplash injury were included. Repeated measures T1-weighted magnetic resonance imaging was used to measure and compare cross-sectional area (CSA) in square millimeters and shape ratio (SR) of the oropharynx at 4 weeks, 3 months, and 6 months postinjury. Subjects were classified at 6 months by their Neck Disability Index scores into the following categories: recovered (less than 8%), mild disability (10%-28%), and moderate/severe disability (greater than 30%). The effects of time and group and the interaction effect of group by time on oropharynx morphometry (CSA, SR) were investigated using repeated-measures, linear, mixed-model analysis. Based on previous research findings, age, gender, and body mass index were entered into the analyses as covariates. Where significant main or interaction effects were detected, pairwise comparisons were performed to investigate specific differences in the dependent variable between groups and within groups over time. RESULTS: There was a significant interaction effect for group by time for both the CSA and SR values. Age significantly influenced SR (P = .024) and body mass index significantly influenced CSA (P = .001). There was no difference in CSA or SR across all groups at 4 weeks postinjury. However, at 6 months, CSA was significantly different between the recovered group and the moderate/severe group (P = .001). The recovered group demonstrated a significant increase in CSA (P = .04) over time, whereas the moderate/severe group significantly decreased (P = .01). At 6 months, the moderate/severe group had a reduced SR compared to the mild group (P = .03). No differences in CSA or SR of the oropharynx were found between the mild and recovered groups throughout the study. CONCLUSION: Temporal reductions in CSA of the oropharynx occur following whiplash and persist to a greater extent in those with moderate/severe symptoms at 6 months postinjury. Studies are planned (1) to better investigate the underlying mechanisms of CSA reductions, (2) to determine their relevance to functional recovery and production of voice following whiplash, and (3) to evaluate multidisciplinary assessment and management of these patients.