Muscle trigger points, pressure pain threshold, and cervical range of motion in patients with high level of disability related to acute whiplash injury

STUDY DESIGN: Cross-sectional cohort study. OBJECTIVE: To analyze the differences in the prevalence of trigger points (TrPs) between patients with acute whiplash-associated disorders (WADs) and healthy controls, and to determine if widespread pressure hypersensitivity and reduced cervical range of motion are related to the presence of TrPs in patients with acute WADs. BACKGROUND: The relationship between active TrPs and central sensitization is not well understood in patients with acute WADs. METHODS: Twenty individuals with a high level of disability related to acute WAD and 20 age- and sex-matched controls participated in the study. TrPs in the temporalis, masseter, upper trapezius, levator scapulae, sternocleidomastoid, suboccipital, and scalene muscles were examined. TrPs are defined as hypersensitive spots in a palpable taut band, producing a local twitch response and referred pain when palpated. Pressure pain threshold (PPT) was assessed bilaterally over the C5-6 zygapophyseal joints, second metacarpal, and tibialis anterior muscle. Active cervical range of motion, neck pain, and self-rated disability using the Neck Disability Index were also assessed. RESULTS: The mean ± SD number of TrPs for the patients with acute WADs was 7.3 ± 2.8 (3.4 ± 2.7 were latent TrPs; 3.9 ± 2.5 were active TrPs). In comparison, healthy controls had 1.7 ± 2.2 latent and no active TrPs (