Physical and psychological factors predict outcome following whiplash injury

Does the presence of sensory hypersensitivity influence outcomes of physical rehabilitation for chronic whiplash? – A preliminary RCT

Patients with chronic whiplash associated disorders present with varied sensory, motor and psychological features. In this first instance it was questioned whether a multimodal program of physical therapies was an appropriate management to be broadly prescribed for these patients when it was known that some would have sensory features suggestive of a notable pain syndrome. A randomised controlled trial was conducted with 71 participants with persistent neck pain following a motor vehicle crash to explore this question. Participants were randomly allocated to receive either a multimodal physiotherapy program (MPT) or a self-management program (SMP) (advice and exercise). In the randomisation process, participants were stratified according to the presence or not of widespread mechanical or cold hyperalgesia. The intervention period was 10 weeks and outcomes were assessed immediately following treatment. Even with the presence of sensory hypersensitivity in 72.5% of subjects, both groups reported some relief of neck pain and disability (Neck Disability Index) and it was superior in the group receiving multimodal physiotherapy (p=0.04). Post-hoc observations however suggested that relief was marginal in the subgroup with both widespread mechanical and cold hyperalgesia. Further research is required to test the validity of this sub-group observation and to test the effect of the intervention in the long term.

Evaluation of the core outcome measure in whiplash

STUDY DESIGN

Reanalysis of data derived from longitudinal cohort studies.

OBJECTIVE

To comprehensively evaluate the psychometric properties of a 5-item version of the Core Outcome Measure in people with whiplash.

SUMMARY OF BACKGROUND DATA

The 7-item Core Outcome Measure was initially proposed as a brief health outcome measure for use in low back pain. To date, this measure has not been comprehensively assessed in a whiplash population. METHOD.: Data were sourced from 3 separate whiplash cohorts (total 481) encompassing acute, early chronic, and late-chronic whiplash among primary care and insurance populations. Subjects completed a 5-item version of the Core Outcome Measure for whiplash (Core Whiplash Outcome Measure [CWOM]), the Functional Rating Index, Neck Disability Index, SF-36, and perceived recovery questionnaires at baseline and short and long-term follow-up periods. Psychometric evaluation of the CWOM included assessing questionnaire responses, internal consistency, construct validity, and internal and external responsiveness.

RESULTS

Internal consistency was excellent at all stages of whiplash (Cronbach alpha = 0.76 in the acute stage and 0.83 in the late-chronic stage). Convergent validity was observed between the CWOM and Functional Rating Index (Pearson r = 0.81), Neck Disability Index (Pearson r = 0.76), and SF-36 physical health summary measure (Pearson r = -0.65). Divergent validity was observed between the CWOM and SF-36 mental health summary measure (Pearson r = -0.45). The internal and external responsiveness of the CWOM was similar to other neck-specific outcome measures.

CONCLUSIONS

We recommend the 5-item CWOM as a brief clinical measure for whiplash because it is quick to administer and score, and has excellent measurement properties. The CWOM may need to be supplemented with other questionnaires (e.g., when assessment of psychological or emotional health is required).

[Problems involved in expert opinions on acceleration injuries of the cervical spine]

Reasons for problems in stating an expert opinion on acceleration injuries of the cervical spine are numerous. The presence of unexpected or the absence of expected symptoms, the lack of objective proof for alterations or the presence of complaints that are difficult to prove, the discrepancy between recognizable force of the impact versus the resulting damage to the injured as well as the chance of being completely incapable of rendering proof that unquestionably a potentially damage-causing event is--beyond any reasonable doubt--the origin of an observed alteration in an injured individual are some of the problems a medical expert has to face when dealing with the analysis of injuries of the cervical spine. Unsatisfactory documentation in the patient's records, discussions about the reliability of diagnostic means or the interpretation of their results, difficult to procure evidence of accident-specific biomechanics and their direct or indirect impact on the body or neck of the injured person as well as distinguishing cervical sprain from mild brain damage, post-traumatic distress syndrome, cognitive disorder, psychiatric disease, aggravation, or malingering makes it hard for an expert to state an expert opinion.

The influence of prognostic factors on neck pain intensity, disability, anxiety and depression over a 2-year period in subjects with acute whiplash injury

The influence of potential prognostic factors (occupant- and crash-related factors, initial neck pain intensity and headache, whiplash injury severity, helplessness, locus of control, socioeconomic status) on neck pain intensity (VAS), disability (DRI), anxiety and depression (HADS) was estimated in a cohort of 3704 subjects with whiplash injury following a motor vehicle crash. Questionnaires were administered (baseline, 1-, 6-, 12-, 24-month follow-ups). VAS was trichotomized; "low" (0-30), "moderate" (31-54), "severe" (55-100). A cumulative logit model with a proportional odds assumption was applied. Results regarding depression differed somewhat from the other outcomes. Overall, initial neck pain intensity was an important prognostic factor, but acted also as an evident effect modifier. Females had slightly increased odds for all outcomes but depression, for which no gender differences were shown. Injury severity was associated with all outcomes, but was most pronounced regarding disability among those who perceived numbness/pain in arms/hands and also had severe initial neck pain (proportional odds ratio [OR] 6.5; 95% confidence interval [CI] 2.5-17.0). Initial headache influenced all outcomes. Income was not related to any of the outcomes, whereas a lower level of education was associated with all outcomes but depression. Locus of control was not a factor of importance. In contrast, helplessness was related to all outcomes, but was most pronounced regarding neck pain intensity and depression for subjects with severe initial neck pain (OR 4.8; 95% CI 2.9-7.8; OR 6.6; 95% CI 2.6-17.0). Associations seem to be established early, and then to be relatively constant over time.

A prospective cohort study of health outcomes following whiplash associated disorders in an Australian population

OBJECTIVE

To define health outcomes of whiplash associated disorders (WAD) at three months, six months, and two years after injury and to examine predictors of these outcomes.

DESIGN

Prospective cohort study.

SETTING

New South Wales, Australia.

SUBJECTS

People with compensable motor crash injuries who reported whiplash as one of their injuries.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Functional Rating Index (FRI), Short Form 36 (SF-36) at three months, six months, and two years after injury, ascertained by telephone interview.

RESULTS

At three months, 33.6% of the cohort was recovered (as defined by FRI<or=25), increasing marginally at six months (38.9% recovered), but more significantly at two years (51.7% recovered, p = 0.001). The mean physical component score of the SF-36 improved at each time point (p = 0.002), while the mean mental component score did not (p = 0.59). Predictors of recovery at two years (as defined by global perceived effect) included a lower FRI index at baseline (p = 0.001) and closure of the claim at two years (p = 0.02).

CONCLUSION

Whiplash injury had a large effect on the health of this Australian cohort of whiplash sufferers, with only 50% of the cohort recovered at two years. Physical measures of health appear to improve over time, whereas mental measures of health did not. Despite this, this cohort is largely able to participate in activities and work at two years. Prevention of chronic disability may lie with concentration of resources to those who score highly on the FRI at baseline. In addition, chronic psychological ill health may be prevented by directing treatment to those with poor scores on sensitive measures of psychological ill health at baseline.

Influence of sympathetic nervous system on sensorimotor function: whiplash associated disorders (WAD) as a model

There is increasing interest about the possible involvement of the sympathetic nervous system (SNS) in initiation and maintenance of chronic muscle pain syndromes of different aetiology. Epidemiological data show that stresses of different nature, e.g. work-related, psychosocial, etc., typically characterised by SNS activation, may be a co-factor in the development of the pain syndrome and/or negatively affect its time course. In spite of their clear traumatic origin, whiplash associated disorders (WAD) appear to share many common features with other chronic pain syndromes affecting the musculo-skeletal system. These features do not only include symptoms, like type of pain or sensory and motor dysfunctions, but possibly also some of the pathophysiological mechanisms that may concur to establish the chronic pain syndrome. This review focuses on WAD, particular emphasis being devoted to sensorimotor symptoms, and on the actions exerted by the sympathetic system at muscle level. Besides its well-known action on muscle blood flow, the SNS is able to affect the contractility of muscle fibres, to modulate the proprioceptive information arising from the muscle spindle receptors and, under certain conditions, to modulate nociceptive information. Furthermore, the activity of the SNS itself is in turn affected by muscle conditions, such as its current state of activity, fatigue and pain signals originating in the muscle. The possible involvement of the SNS in the development of WAD is discussed in light of the several positive feedback loops in which it is implicated.

Randomized controlled trial of exercise for chronic whiplash-associated disorders

Whiplash-associated disorders are common and incur considerable expense in social and economic terms. There are no known effective treatments for those people whose pain and disability persist beyond 3 months. We conducted a randomized, assessor-blinded, controlled trial at two centres in Australia. All participants received 3 advice sessions. In addition the experimental group participated in 12 exercise sessions over 6 weeks. Primary outcomes were pain intensity, pain bothersomeness and function measured at 6 weeks and 12 months. Exercise and advice was more effective than advice alone at 6 weeks for all primary outcomes but not at 12 months. The effect of exercise on the 0-10 pain intensity scale was -1.1 (95%CI -1.8 to -0.3, p=0.005) at 6 weeks and -0.2 (0.6 to -1.0, p=0.59) at 12 months; on the bothersomeness scale the effect was -1.0 (-1.9 to -0.2, p=0.003) at 6 weeks and 0.3 (-0.6 to 1.3, p=0.48) at 12 months. The effect on function was 0.9 (0.3 to 1.6, p=0.006) at 6 weeks and 0.6 (-0.1 to 1.4, p=0.10) at 12 months. High levels of baseline pain intensity were associated with greater treatment effects at 6 weeks and high levels of baseline disability were associated with greater treatment effects at 12 months. In the short-term exercise and advice is slightly more effective than advice alone for people with persisting pain and disability following whiplash. Exercise is more effective for subjects with higher baseline pain and disability.

Mechanisms underlying development of spatially distributed chronic pain (fibromyalgia)

Chronic fibromyalgia (FM) pain is prevalent (estimated as high as 13%), predominantly affects women, and is associated with a variety of focal pain conditions. Ongoing FM pain is referred to deep tissues and is described as widespread but usually is maximally located within a restricted region such as the shoulders. Palpation of deep tissues reveals an enhanced nociceptive sensitivity that is not restricted to regions of clinical pain. Similarly, psychophysical testing reveals allodynia and hyperalgesia for cutaneous stimulation at locations beyond regions of clinical pain referral. The combination of widely distributed clinical pain and generalized hypersensitivity is highly disabling, but no satisfactory treatment is regularly prescribed. A thorough understanding of mechanisms will likely be required to develop and document adequate therapies. The generalized hypersensitivity associated with FM has focused considerable interest on central (CNS) mechanisms for the disorder. These include central sensitization, central disinhibition and a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis. However, the central effects associated with FM can be produced by a peripheral source of pain. Chronic nociceptive input induces central sensitization, magnifying pain, and it activates the HPA and the sympathetic nervous system. Chronic sympathetic activation indirectly sensitizes peripheral nociceptors and sets up a vicious cycle. Thus, it appears that central mechanisms of FM pain are dependent on abnormal peripheral input(s) for development and maintenance of this condition. A substantial literature defines peripheral-CNS-peripheral interactions that are integral to FM pain. These reciprocal actions and related phenomena of relevance to FM pain are reviewed here, leading to suggestions for testing of therapeutic approaches.

Central Hypersensitivity in Chronic Pain: Mechanisms and Clinical Implications

The available literature consistently shows increased pain sensitivity after sensory stimulation of healthy tissues in patients who have various chronic pain conditions. This indicates a state of hypersensitivity of the CNS that amplifies the nociceptive input arising from damaged tissues. Experimental data indicate that central hypersensitivity is probably induced primarily by nociceptive input arising from a diseased tissue. In patients, imbalance of descending modulatory systems connected with psychologic distress may play a role. There is experimental support in animal studies for the persistence of central hypersensitivity after complete resolution of tissue damage. This is particularly true for neuropathic pain conditions, whereby potentially irreversible plasticity changes of the CNS have been documented in animal studies. Whether such changes are present in musculoskeletal pain states is at present uncertain. Despite the likely importance of central hypersensitivity in the pathophysiology of chronic pain, this mechanism should not be used to justify the lack of understanding on the anatomic origin of the pain complaints in several pain syndromes, which is mostly due to limitations of the available diagnostic tools. Treatment strategies for central hypersensitivity in patients have been investigated mostly in neuropathic pain states. Possible therapy modalities for central hypersensitivity in chronic pain of musculoskeletal origin are largely unexplored. The limited evidence available and everyday practice show, at best, modest efficacy of the available treatment modalities for central hypersensitivity. The gap between basic knowledge and clinical benefits remains large and should stimulate further intensive research.

Physical and psychological factors maintain long-term predictive capacity post-whiplash injury

Higher initial levels of pain and disability, older age, cold hyperalgesia, impaired sympathetic vasoconstriction and moderate post-traumatic stress symptoms have been shown to be associated with poor outcome 6 months following whiplash injury. This study prospectively investigated the predictive capacity of these variables at a long-term follow-up. Sixty-five of an initial cohort of 76 acutely injured whiplash participants were followed to 2-3 years post-accident. Motor function (ROM; kinaesthetic sense; activity of the superficial neck flexors (EMG) during cranio-cervical flexion), quantitative sensory testing (pressure, thermal pain thresholds and brachial plexus provocation test), sympathetic vasoconstrictor responses and psychological distress (GHQ-28, TSK and IES) were measured. The outcome measure was Neck Disability Index (NDI) scores. Participants with ongoing moderate/severe symptoms at 2-3 years continued to manifest decreased ROM, increased EMG during cranio-cervical flexion, sensory hypersensitivity and elevated levels of psychological distress when compared to recovered participants and those with milder symptoms. The latter two groups showed only persistent deficits in cervical muscle recruitment patterns. Higher initial NDI scores (OR 1.00-1.1), older age (OR 1.00-1.13), cold hyperalgesia (OR 1.1-1.13) and post-traumatic stress symptoms (OR 1.03-1.2) remained significant predictors of poor outcome at long-term follow-up (r2=0.56). The robustness of these physical and psychological factors suggests that their assessment in the acute stage following whiplash injury will be important.

Predictors of persistent neck pain after whiplash injury

OBJECTIVE

To establish the aetiological influences of persistent neck pain following a motor vehicle collision and to construct a model for use in the emergency department for identifying patients at high risk of persistent symptoms.

DESIGN

Prospective cohort study. Patients recruited from hospital emergency departments were sent a questionnaire to gather information on various exposures. They were followed up at 1, 3, and 12 months to identify those with persistent symptoms.

MAIN OUTCOME MEASURE

Persistent neck pain (pain at 1, 3, and 12 months after collision).

RESULTS

The baseline survey included 765 patients. Subsequently, 480 completed a questionnaire at each follow up time point, of whom 128 (27%) reported neck pain on each occasion. Few collision specific factors predicted persistent neck pain. In contrast, a high level of general psychological distress, pre-collision history of widespread body pain, type of vehicle, whiplash associated symptoms, and initial neck disability best predicted the persistence of symptoms. Furthermore, these factors, in combination, accounted for more than a fivefold increase in the risk of persistent neck pain.

CONCLUSION

The greatest predictors of persistent neck pain following a motor vehicle collision relate to psychological distress and aspects of pre-collision health rather than to various attributes of the collision itself. With these factors, and those relating to initial injury severity, it is possible to identify a subgroup of patients presenting with neck pain with the highest risk of persistent symptoms. Thus, it is possible to identify whiplash patients with a poor prognosis and to provide closer follow up and specific attention to management in these individuals.

The relationship between sensory and sympathetic nervous system changes and posttraumatic stress reaction following whiplash injury--a prospective study

OBJECTIVE

To investigate differences in sensory and sympathetic nervous system (SNS) function between whiplash-injured persons with and without a posttraumatic stress reaction (PTSR). To explore associations between sensory, SNS function, and persistent PTSR at 6 months postinjury.

METHODS

Seventy-six acutely (<1 month) whiplash-injured persons (10 with PTSR persisting to 6 months postinjury, 14 with early PTSR that resolved, and 52 with no PTSR) were prospectively investigated.

RESULTS

Those with persistent PTSR showed sensory hypersensitivity and impaired peripheral vasoconstriction compared to those whose PTSR resolved and those without PTSR (P<.05). The early presence of sensory hypersensitivity was associated with PTSR at 6 months, but this relationship was mediated by pain and disability levels. Impaired vasoconstriction and higher pain and disability levels were associated with PTSR at 6 months.

CONCLUSION

Sensory disturbances following whiplash injury are associated with persistent PTSR but may be mediated by levels of pain and disability.

Persistent myalgia following whiplash

Persistent myalgia following whiplash is commonly considered the result of poor psychosocial status, illness behavior, or failing coping skills. However, there is much evidence that persistent myalgia may be due to neurophysiologic mechanisms involving peripheral and central sensitization. Myofascial trigger points may play a crucial role in maintaining sensitization. Recent research suggests that the chemical environment of myofascial trigger points is an important factor. Several consequences are reviewed when central pain mechanisms and myofascial trigger points are included in the differential diagnosis and in the management of patients with persistent pain following whiplash.

The development of persistent pain and psychological morbidity after motor vehicle collision: integrating the potential role of stress response systems into a biopsychosocial model

OBJECTIVES

Persistent pain and psychological sequelae are common after motor vehicle collision (MVC), but their etiology remains poorly understood. Such common sequelae include whiplash-associated disorders (WAD), fibromyalgia, and posttraumatic stress disorder (PTSD). Increasing evidence suggests that these disorders share overlapping epidemiologic and clinical features. A model is proposed in which central neurobiological systems, including physiologic systems and neuroanatomical structures involved in the stress response, are an important substrate for the development of all 3 disorders and interact with psychosocial and other factors to influence chronic symptom development.

METHODS

Epidemiologic and clinical characteristics regarding the development of these disorders after MVC are reviewed. Evidence suggesting a role for stress response systems in the development of these disorders is presented.

RESULTS

Contemporary evidence supports a model of chronic symptom development that incorporates the potential for interactions between past experience, acute stress responses to trauma, post-MVC behavior, and cognitive/psychosocial consequences to alter activity within brain regions which process pain and to result in persistent pain, as well as psychological sequelae, after MVC. Such a model incorporates factors identified in prior biopsychosocial theories and places them in the landscape of our rapidly developing understanding of stress systems and CNS pain-modulating pathways.

CONCLUSION

New models are needed to stimulate deeper examination of the interacting influences of initial tissue damage, acute pain, psychosocial contingencies, and central stress pathways during chronic symptom development after MVC. Deeper understanding could contribute to improved treatment approaches to reduce the immense personal and societal burdens of common trauma-related disorders.