Abstract: BACKGROUND: There exits some similarity between symptoms of carpal tunnel syndrome (CTS) and myofascial pain related to trigger points (TPs) in the infraspinatus muscle. AIM: The aim was to examine what proportion of patients referred with a clinical suspicion of CTS had myofascial pain in the infraspinatus muscles and how their occurrence was related to the outcome of nerve conduction studies (NCS). METHODS: We examined the occurrence of CTS and of TPs in infraspinatus muscles in a cohort of patients suspected for CTS and referred to the Department of Clinical Neurophysiology, Aarhus University Hospital from October 2003 to February 2004. Patients underwent electrodiagnostic studies of the median and ulnar nerves. Additional tests were performed if necessary. Patients were examined for TPs by a blinded examiner immediately after NCS. RESULTS: We included 335 patients (202 females; 133 males, mean age 46). Two hundred one patients (60%) had abnormal NCS indicating CTS. Fifteen patients (4%) had other electrodiagnostic abnormalities. One hundred nineteen patients (36%) had normal NCS. Forty nine percent (58 out of 119) of the subjects with normal NCS had TPs in the infraspinatus muscles whereas only 26% (53 out of 201) of the patients with abnormal NCS indicating CTS had TPs. Likewise, 26% (4 out of 15) of the patients with other electrodiagnostic abnormalities had TPs. CONCLUSIONS: Approximately one third of patients referred with a clinical suspicion of CTS had TPs in the infraspinatus muscles. This occurrence was higher in the group with normal NCS than in the group with abnormal NCS indicating CTS. When CTS is suspected clinically, physicians must be aware of TPs in the infraspinatus muscles as a possible cause of the symptoms; thus, NCS are important in these patients.

Abstract: Chronic whiplash-associated disorder (WAD) represents a major medical and psycho-social problem. The typical symptomatology presented in WAD is to some extent similar to symptoms of post traumatic stress disorder. In this study we examined if the acute stress reaction following a whiplash injury predicted long-term sequelae. Participants with acute whiplash-associated symptoms after a motor vehicle accident were recruited from emergency units and general practitioners. The predictor variable was the sum score of the impact of event scale (IES) completed within 10 days after the accident. The main outcome-measures were neck pain and headache, neck disability, general health, and working ability one year after the accident. A total of 737 participants were included and completed the IES, and 668 (91%) participated in the 1-year follow-up. A baseline IES-score denoting a moderate to severe stress response was obtained by 13% of the participants. This was associated with increased risk of considerable persistent pain (OR=3.3; 1.8-5.9), neck disability (OR=3.2; 1.7-6.0), reduced working ability (OR=2.8; 1.6-4.9), and lowered self-reported general health one year after the accident. These associations were modified by baseline neck pain intensity. It was not possible to distinguish between participants who recovered and those who did not by means of the IES (AUC=0.6). In conclusion, the association between the acute stress reaction and persistent WAD suggests that post traumatic stress reaction may be important to consider in the early management of whiplash injury. However, the emotional response did not predict chronicity in individuals.

Abstract: STUDY DESIGN: Randomized parallel-group trial with 1-year follow-up. OBJECTIVE: To evaluate whether education of patients communicated orally by a specially trained nurse is superior to giving patients a pamphlet after a whiplash injury. SUMMARY OF BACKGROUND DATA: Long-lasting pain and physical disability after whiplash injuries are related to both serious personal suffering and huge socio-economic costs. Pure educational interventions after such injuries seem generally as effective as more costly interventions, but it is unknown if the way advice is communicated is of any importance. METHODS: Participants with relatively mild complaints after car collisions were recruited from emergency departments and GPs. A total of 182 participants were randomized to either: (1) a 1 hour-educational session with a specially trained nurse, or (2) an educational pamphlet. Outcome parameters were neck pain, headache, disability, and return to work. Recovery was defined as scoring pain 0 or 1 (0-10 point scale) and not being off sick at the time of the follow-ups. RESULTS: After 3, 6, and 12 months 60%, 58%, and 66%, respectively of the participants had recovered. Group differences were nonsignificant on all outcome parameters, even though the outcome tended to be better for the group receiving personal advice. CONCLUSION: Prognosis did not differ between patients who received personal education and those who got a pamphlet. However, a systematic tendency toward better outcome with personal communicated information was observed and the question how patients should be educated to reduce the risk of chronicity after whiplash is worth further investigation, since no treatment have been proven to prevent long-lasting symptoms, and all forms of advice or educational therapy are so cheap that even a modest effect justifies its use.

Abstract: OBJECTIVE: To evaluate the ability of early smooth pursuit testing to predict chronic whiplash-associated disorders, and to study whether the presence of abnormal smooth pursuit eye movements at one-year follow-up is associated with symptoms at that time. DESIGN: Prospective cohort study with one-year follow-up. SETTING: The study was carried out at a university research centre and participants were recruited from emergency units and general practitioners. SUBJECTS: In all, 262 participants were recruited within 10 days from a whiplash injury. MAIN MEASURES: Smooth pursuit eye movements were tested with electrooculography (EOG) an average of 12 days after a whiplash trauma and again after one year. Analyses of EOG recordings were computerized. Associations between test results both from baseline and one-year tests and self-reported neck pain, headache, neck disability and working ability one year after the car collision were determined. RESULTS: Results of early eye movement tests were not associated with the prognosis. Reduced smooth pursuit performance when tested in static cervical rotation at the one-year follow-up was significantly associated with higher neck pain intensity at that time (regression coefficient 0.8, 95% confidence interval (CI) 0.04-1.5), but the association was too weak for the test to discriminate between recovered participants and those with lasting symptoms. CONCLUSIONS: Although reduced smooth pursuit performance at one-year follow-up was associated with persistent neck pain, smooth pursuit eye movement tests are not useful as predictive or diagnostic tests in whiplash-associated disorders.

Abstract: BACKGROUND AND PURPOSE: Physical mechanisms are the possible factors involved in the development and maintenance of long-term handicaps after acute whiplash injury. This study prospectively examined the role of active neck mobility, cervical and extra-cervical pains, as well as non-painful complaints after a whiplash injury as predictors for subsequent handicap. METHODS: Consecutive acute whiplash patients (n = 688) were interviewed and examined by a study nurse after the median of 5 days after injury, and divided into a high- or a low-risk group by an algorithm based on pain intensity, number of non-painful complaints and active neck mobility [active cervical range of motion (CROM)]. All 458 high-risk patients and 230 low-risk patients received mailed questionnaires after 3, 6 and 12 months. Two examiners examined all high-risk patients (n = 458) and 41 consecutive low-risk patients at median 11, 109, 380 days after injury. The main outcome measures were: handicaps, severe headaches, neck pain and neck disability. RESULTS: The relative risk for a 1-year disability increased by 3.5 with initial intense neck pain and headaches, by 4.6 times with reduced CROM and by four times with multiple non-painful complaints. CONCLUSION: Reduced active neck mobility, immediate intense neck pain and headaches and the presence of multiple non-painful complaints are the important prognostic factors for a 1-year handicap after acute whiplash.

Abstract: Local sensitization to noxious stimuli has been previously described in acute whiplash injury and has been suggested to be a risk factor for chronic sequelae following acute whiplash injury. In this study, we prospectively examined the development of tender points and mechano-sensitivity in 157 acute whiplash injured patients, who fulfilled criteria for WAD grade 2 (n=153) or grade 3 (n=4) seen about 5 days after injury (4.8+/-2.3) and who subsequently had or had not recovered 1 year after a cervical sprain. Tender point scores and stimulus-response function for mechanical pressure were determined in injured and non-injured body regions at specific time-points after injury. Thirty-six of 157 WAD grade 2 patients (22.9%) had not recovered, defined as reduced work capacity after 1 year. Non-recovered patients had higher total tender point scores after 12 (p<0.05), 107 (p<0.05) and 384 days (p<0.05) relative to those who recovered. Tenderness was found in the neck region and in remote areas in non-recovered patients. The stimulus-response curves for recovered and non-recovered patients were similar after 12 days and 107 days after the injury, but non-recovered patients had steeper stimulus-response curves for the masseter (p<0.02) and trapezius muscles (p<0.04) after 384 days. This study shows early mechano-sensitization after an acute whiplash injury and the development of further sensitization in patients with long-term disability.

Abstract: STUDY DESIGN: Randomized, parallel-group trial. OBJECTIVE: To compare the effect of 3 early intervention strategies following whiplash injury. SUMMARY OF BACKGROUND DATA: Long-lasting pain and disability, known as chronic whiplash-associated disorder (WAD), may develop after a forced flexion-extension trauma to the cervical spine. It is unclear whether this, in some cases disabling, condition can be prevented by early intervention. Active interventions have been recommended but have not been compared with information only. METHODS: Participants were recruited from emergency units and general practitioners within 10 days after a whiplash injury and randomized to: 1) immobilization of the cervical spine in a rigid collar followed by active mobilization, 2) advice to "act-as-usual," or 3) an active mobilization program (Mechanical Diagnosis and Therapy). Follow-up was carried out after 3, 6, and 12 months postinjury. Treatment effect was measured in terms of headache and neck pain intensity (0-10), disability, and work capability. RESULTS: A total of 458 participants were included. At the 1-year follow-up, 48% of participants reported considerable neck pain, 53% disability, and 14% were still sick listed at 1 year follow-up. No significant differences were observed between the 3 interventions group. CONCLUSION: Immobilization, "act-as-usual," and mobilization had similar effects regarding prevention of pain, disability, and work capability 1 year after a whiplash injury.

Abstract: BACKGROUND: Recent studies have reported a potential analgesic effect of botulinum toxin A (BTXA) in musculoskeletal pain. The present double-blind, randomized, placebo-controlled, parallel clinical trial studied the effect of BTXA on pain from muscle trigger points and on EMG activity at rest and during voluntary contraction. METHODS: Thirty patients with trigger points in the infraspinatus muscles received either 50 units/0.25 mL of BTXA or 0.25 mL of isotonic saline. Baseline measures were determined during a run-in period of 1 week. Outcome measures including local and referred spontaneous pain, pain detection and tolerance thresholds to mechanical pressure, and shoulder movement were assessed at 3 and 28 days after injection. The interference pattern of the EMG during maximal voluntary effort of infraspinatus muscle was recorded and a standardized search for spontaneous electrical motor endplate activity at the trigger points was performed before and 28 days after BTXA or saline injection. RESULTS: BTXA reduced motor endplate activity and the interference pattern of EMG significantly but had no effect on either pain (spontaneous or referred) or pain thresholds compared with isotonic saline. CONCLUSIONS: The results do not support a specific antinociceptive and analgesic effect of botulinum toxin A.

Abstract: Muscle pain is often accompanied by a feeling of muscle fatigue and weakness. We examined the effect of experimental muscle pain on the electromyogram (EMG) during maximal voluntary contraction (MVC), and on the compound muscle action potential (CMAP) of the brachial biceps muscle. Twenty-one healthy subjects were injected intramuscularly with 0.1 ml/30 microg of the vanilloid receptor agonist (capsaicin) or 0.2 ml of 5% hypertonic saline. A Teflon-coated cannulated EMG needle was used to record the EMG interference pattern (IP) at MVC. The CMAP of the brachial biceps muscle was obtained by stimulation of the musculocutaneous nerve at the axilla using surface electrodes. Amplitude, mean frequency of the power spectrum, and turns/s of the interference pattern were reduced after pain induced by capsaicin or hypertonic saline. Latency, amplitude, and area-under-curve of the CMAP did not change after injection of either substance. Acute stimulation of muscle nociceptors thus produced a fatiguelike change in the interference pattern during MVC, possibly due to a decrease in motoneuron firing rate and increased muscle fatigability.

Abstract: Whiplash injury and chronic whiplash syndrome represent major health problems in certain western communities, pain being the main symptom. Sensitization of the nociceptive system may play a role for non-recovery after whiplash injury. AIMS: This study examined if tolerance to endure pain stimuli may predict outcome in whiplash injury. In a prospective fashion, 141 acute whiplash patients exposed to rear-end car collision (WAD grade 1-3) and 40 ankle-injured controls were followed and exposed to a cold pressor test, respectively, 1 week, 1, 3, 6 and 12 months after the injury. VAS score of pain and discomfort was obtained before, during and after immersion of the dominant hand into cold water for 2 min. The McGill Pain Questionnaire showed that ankle-injured controls had higher initial pain scores than the corresponding whiplash group, while whiplash-injured subjects had higher scores at 6 months; pain scores being similar at other time points. No difference was found in cold pressor pain between recovered whiplash patients and ankle-injured subjects. Non-recovery was only encountered in whiplash injury. Eleven non-recovered whiplash patients (defined as: handicap after 1 year) showed reduced time to peak pain from 1 week to 3 months (P<0.001), 6 months (P<0.01), but not 12 months after the injury. A larger pain area was seen in non-recovered vs. recovered whiplash-injured subjects during the entire observation period (P<0.001). Non-recovery after whiplash was associated with initially reduced cold pressor pain endurance and increased peak pain, suggesting that dysfunction of central pain modulating control systems plays a role in chronic pain after acute whiplash injury.