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

Abstract

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. Repeatedmeasures 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 beer 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. Copyright © 2012 Journal of Orthopaedic & Sports Physical Therapy.