Jaw-neck motor function in the acute stage after whiplash trauma.

Background: Jaw-neck motor function is affected in the chronic stage following whiplash trauma. It is not known whether motor function is affected also in the early stage after neck trauma.

Objectives: To determine how jaw and head movement amplitudes and movement cycle times correlate with jaw and neck pain, and neck disability in the acute stage after whiplash trauma.

Methods: Jaw and head movements during jaw opening-closing were recorded with an optoelectronic system in 23 cases (4 men, 19 women, 18-66 years) within 1 month after whiplash trauma and compared with 27 controls without neck trauma (15 men, 12 women, 20-66 years). Jaw and head movement amplitudes, head/jaw ratio (quotient of head and jaw movement amplitude) and movement cycle times were evaluated in relation to jaw and neck pain (Numeric Rating Scale) and neck disability (Neck Disability Index). Analyses were performed with Mann-Whitney U test and Spearman's correlation.

Results: Compared with controls, cases showed smaller jaw movement amplitudes (P = .006) but no difference in head movement amplitudes, head/jaw ratios or movement cycle times. There were no significant correlations between movement amplitudes or cycle times and jaw and neck pain, and neck disability. Cases with high neck pain intensity had smaller jaw movement amplitudes compared to cases with low neck pain intensity (P = .024).

Conclusion: The results suggest that jaw-neck motor function may be affected in the acute stage after whiplash trauma and more so in cases with higher neck pain intensity.