Central Sensitization Is Modulated Following Trigger Point Anesthetization in Patients with Chronic Pain from Whiplash Trauma. A Double-Blind, Placebo-Controlled, Crossover Study.

Objective: Central sensitization (CS) with low peripheral pain thresholds (PPTs) is a common finding among patients with chronic pain after whiplash (CPWI). While it has been proposed that myofascial myofascial trigger points (MTrPs) may act as modulators of central sensitization, previously reported findings are conflicting and inconclusive. The present study was designed to investigate immediate responsiveness of CS to alterations in nociceptive input. Design: Controlled, double-blind, cross-over. Subjects: Thirty-one patients with chronic pain (trapezius myalgia) and CS after whiplash. Methods: Participants were referred by randomization to group A for injection of a single peripheral pain generator (MTrP or other discrete tender point) with local anesthetic or to group B for sham injection and cross-over. Documentation of PPT (Algometer), maximum jaw opening (caliper), and grip strength (Vigorimeter), as well as subjective overall pain (visual analog scale [VAS]), was made before and after each intervention. Results: Statistical analysis of data (Student's t test, analysis of variance) confirmed that peripheral pain thresholds were significantly higher and maximum jaw opening significantly greater after anesthetizing a focal pain generator in the trapezius, but not after a sham injection. In contrast with the objective variables, subjective generalized pain improved (VAS) after not only an injection of local anesthetic, but also, and to a similar extent, after a sham injection. Conclusions: CS, as expressed by lowered PPT, is a rapidly adjusting physiological response to nociceptive stimuli in some patients with chronic pain after whiplash. PPT are likely modulated by myofascial tender points in selected patients with CS. With reference to the present findings, surgical ablation of MTrPs is discussed as a potential treatment modality for CS.

Case report: whiplash-associated disorder from a low-velocity bumper car collision: history, evaluation, and surgery.

STUDY DESIGN: Case report of a patient with a whiplash-associated disorder following a bumper car collision. Imaging studies failed to provide an anatomic explanation for the debilitating symptoms. OBJECTIVES: To report a chronic, debilitating pain syndrome after a low-velocity bumper car collision while using complex range-of-motion data for the diagnosis, prognosis, and surgical indication in whiplash-associated disorder. SUMMARY OF BACKGROUND DATA: The controversy of whiplash-associated disorder mainly concerns pathophysiology and collision dynamics. Although many investigations attempt to define a universal lesion or determine a threshold of force that may cause permanent injury, no consensus has been reached. METHODS: Eight years after a low-velocity collision, the patient underwent surgical excision of multiple painful trigger points in the posterior neck. Computerized motion analysis was used for pre- and postoperative evaluations. RESULTS: Surgical treatment resulted in an increase in total active range of motion by 20%, reduced intake of pain medication, doubled the number of work hours, and generally led to a dramatic improvement in quality of life. CONCLUSIONS: This case of whiplash-associated disorder after a low-velocity collision highlights the difficulty in defining threshold of injury in regard to velocity. It also illustrates the value of computerized motion analysis in confirming the diagnosis of whiplash-associated disorder and in the evaluation of prognosis and treatment.