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Toward Optimal Early Management After Whiplash Injury to Lessen the Rate of Transition to Chronicity: Discussion Paper 5

Jull, Gwendolen A., PT, PhD*; Söderlund, Anne, PT, PhD; Stemper, Brian D., PhD; Kenardy, Justin, PhD§; Gross, Anita R., PT, MSc; Côté, Pierre, DC, PhD; Treleaven, Julia, PT, PhD*; Bogduk, Nikolai, MD, PhD**; Sterling, Michele, PT, PhD††; Curatolo, Michele, MD, PhD‡‡

doi: 10.1097/BRS.0b013e3182388449
Focus Papers: Roundtable
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Study Design. Expert debate and synthesis of research to inform future management approaches for acute whiplash disorders.

Objective. To identify a research agenda toward improving outcomes for acute whiplash-injured individuals to lessen the incidence of transition to chronicity.

Summary of Background Data. International figures are concordant, estimating that 50% of individuals recover from pain and disability within 3 to 6 months of a whiplash injury. The remainder report continuing symptoms up to 1 to 2 years or longer postinjury. As no management approach to date has improved recovery rates, new clinical/research directions are required for early management of whiplash-injured patients.

Methods. A group of multidisciplinary researchers critically debated evidence and current research concerning whiplash from biological, psychological, and social perspectives toward informing future research directions for management of acute whiplash.

Results. It was recognized that effective treatments for acute whiplash are constrained by a limited understanding of causes of whiplash-associated disorders. Acute whiplash presentations are heterogeneous leading to the proposal that a research priority was development of a triage system based on modifiable prognostic indicators and clinical features to better inform individualized early management decisions. Other priorities identified included researching effective early pain management for individuals presenting with moderate to high levels of pain; development of best education/information for acute whiplash; testing the efficacy of stratified and individualized rehabilitation, researching modes of delivery considering psychosocial modulators of pain and disability; and the timing, nature, and mode of delivery of cognitive-behavioral therapies. Directions were highlighted for future biomechanical research into injury prevention.

Conclusion. The burden of whiplash injuries, the high rate of transition to chronicity, and evidence of limited effects of current management on transition rates demand new directions in evaluation and management. Several directions have been proposed for future research, which reflect the potential multifaceted dimensions of an acute whiplash disorder.

Current management of acute whiplash fails to impact rates of chronicity, demanding new clinical/research directions. These include creating a valid triage system to inform early individualized management of this heterogeneous disorder, better pain management, research-informed education and rehabilitation and behavioral therapies, and research into possible tissue damage and its prevention.

*CCRE Spinal Pain, Injury, and Health, Division of Physiotherapy, The University of Queensland, Australia

School of Health, Care and Social Welfare, Mälardalen University, Västerås, Sweden

Department of Neurosurgery, Medical College of Wisconsin, Milwaukee

§Centre of National Research on Disability and Rehabilitation, School of Medicine; School of Psychology, The University of Queensland, St Lucia, Queensland, Australia

Department of Physiotherapy, McMaster University, Hamilton, Ontario, Canada

Dalla Lana School of Public Health, University of Toronto, Toronto and Western Research Institute, Toronto Western Hospital, Toronto, Ontario, Canada

**Department of Clinical Research, Newcastle Bone and Joint Institute, The Royal Newcastle Centre, Newcastle, New South Wales, Australia

††Centre for National Research on Disability and Rehabilitation Medicine, The University of Queensland, Australia

‡‡University Department of Anaesthesiology and Pain Therapy, University of Bern, Inselspital Bern, Switzerland

Address correspondence and reprint requests to: Gwendolen Jull, PhD, CCRE Spinal Pain, Injury, and Health, Division of Physiotherapy, The University of Queensland, St Lucia 4072, Queensland, Australia; E-mail: g.jull@uq.edu.au.

Acknowledgment date: June 16, 2011. First revision date: August 4, 2011. Second revision date: August 25, 2011. Acceptance date: September 19, 2011.

The manuscript submitted does not contain information about medical device(s)/drug(s).

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Whiplash-associated disorders (WAD) are heterogeneous in presentation and recovery rates are variable.1,2 International figures are reasonably concordant indicating that approximately 50% of individuals will recover from pain and disability within 3 to 6 months of injury but the remainder will continue to report symptoms up to 1 to 2 years or longer after the motor vehicle crash.3 Of those who do not recover, between 30% and 40% are likely to have persistent mild to moderate levels of pain and between 10% and 20% will have moderate to severe pain syndromes.4,5 This lack of recovery creates personal, economic, and social burdens. To reduce this burden, the number of individuals who transition to chronicity after whiplash injuries must be reduced. It can be argued that appropriate and effective early management would be pivotal to achieving this aim.

Although the manner in which the whiplash-injured patient is managed in the early stages may be critical to long-term outcome, early management has received comparatively scant attention. The recent review by Teasell et al6 of interventions for the management of acute whiplash (implemented within 2 weeks of injury) identified only 16 randomized controlled trials of varying methodological quality and five nonrandomized trials in the English literature over the past 30 years. The trials involved eclectic approaches in various configurations, including advice to remain active or prescription of exercise in various forms (with or without manipulative therapy), immobilization in a collar, educational interventions, acupuncture, and pulsed electromagnetic field therapy. One study focused on pharmaceutical agents for pain management. The authors concluded on available evidence that activity-based therapies seemed to be more effective. Nevertheless, inspection of these trials reveals that outcomes pertaining to recovery and nonrecovery rates remain relatively consistent, in accord with the findings of a recent systematic review on the course of whiplash.3 No early management approach to date has substantively lessened the incidence of those transitioning to persistent symptoms.

This clearly indicates that new clinical/research directions are required for the early management of the whiplash-injured patient. Research into whiplash has increased and covered injury mechanisms, attendant sensory, psychophysical, sensorimotor, and psychological responses, as well as the potential influences of health care and compensation environments on outcome. It exposes the variety of responses across the biopsychosocial domains, which may help to explain different recovery paths between individuals. Numbers of prospective studies are increasing to better identify prognostic indicators of recovery and nonrecovery, and systematic reviews are providing a clearer, albeit yet incomplete, picture of prognostic factors that may help to inform early evaluation and management approaches.1,2 We have used this knowledge to outline possible future research directions toward optimal early management of WAD, which include the development of a triage system to direct early more individualized management, interventions for identified physical and psychological responses (education, pain management, physical therapies, psychological interventions), as well as research to identify possible tissue lesions and their prevention.

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TRIAGE SYSTEM TO DIRECT EARLY MANAGEMENT

A first priority for a new research direction investigating the management of acute whiplash is recognition that whiplash presents as a heterogeneous disorder from both physical and psychosocial perspectives13,7 and individuals have different recovery paths.5,8 Presentations vary from mild, comparatively simple disorders to complex multifaceted disorders. This suggests that treating patients after a whiplash injury classifiable as WAD I or II9 as a homogenous group with a single treatment approach, as in evidence in many clinical trials to date, may not be the most appropriate approach. Management pathways that recognize heterogeneity and are individualized to patients’ presentations are proposed as a first and vital step toward improving treatment outcomes. This could be facilitated by research informed development of a triage or a subgrouping system10,11 and ultimately the development of a triage tool for use in primary care practice. Ideally, the functions of a triage system would be (1) early identification of categories of persons with likely indicators for good, moderate, or poor long-term prognoses, together with (ii) the clinical identification of pain, psychophysical, physical, psychological responses, or individual factors that could serve to direct early management decisions and appropriate interventions.

Prognostic indicators that are potentially modifiable could form the basis of a triage system. Research into prognostic indicators is evolving. As yet, there is no comprehensive, validated prediction model, but there is sufficient evidence emerging to begin the development of a triage system at this time. The strength of evidence varies for prognostic indicators across biopsychosocial domains, but the level of initial pain and disability is a strong and consistent predictor.14,10,12 There is evidence of three basic patterns of recovery relating to initial pain and disability levels that could be used as the basis to initially triage patients into streams with an anticipated good, moderate, or poor long-term prognosis.5,8 This subgrouping could be strengthened with other features demonstrating prognostic potential. Together with high levels of pain, factors emerging as potentially indicative of a poor prognosis include the presence of headache and multiple symptoms,2,10,11 physical features such as the presence of cold hyperalgesia,4,13 marked loss of neck range of movement,4,13 indicators of psychological distress including symptoms of post-traumatic stress, pain catastrophization, generalized anxiety,2,8 and individual factors such as illness perceptions and poor pain-coping skills.14,15 Notably cold hyperalgesia is absent in those with good to moderate prognoses and its absence distinguished these groups from those with poorer prognoses.4,11,16

In developing a triage system to guide relevant management decisions, presenting clinical features must augment prognostic indicators. There is an increased understanding of psychophysical, neuromuscular, sensorimotor, and psychological responses that can present in the whiplash-injured individual.7,1726 Sociological influences on recovery have also been studied.3,27 Accurate assessment across biopsychosocial domains can potentially provide more precise directions for construction of a management approach that is individualized to the patient as presentations are heterogeneous even within prognostic bands. All possible responses and influences will not be present in all patients, suggesting stratified management approaches as informed by the individual's presenting features and circumstances across a range of domains. This may be facilitated by constructing (currently) best (possible) algorithms for management as part of a future triage tool.

The notion of developing a triage system to guide management is sound in principle, but it demands a body of research. Such a system must be tested for validity and stability and show that it influences outcomes positively and has demonstrable cost benefit. The optimal timing of the use of a triage system needs to be established as pain levels and psychological distress can be very dynamic in the days or weeks after injury. Decisions regarding interventions may be counterproductive if made too early.28,29 Questions to be researched include the relative benefits of a “wait and see” period immediately after injury compared to immediate application of a triage system or whether triage is more effectively implemented at time periods, 1, 2, or 4 weeks after the injury. Alternately, it may be more beneficial to design a staged triage system, for example, one triage for the immediate postinjury period and another for an optimal predetermined time point after injury when initial pain and psychological distress are more stable. In addition, the effect of nonmodifiable prognostic indicators such as no secondary school education, older age, female sex2 on triage, and care pathways needs to be understood. Translational work would be required using best evidence, implementation approaches to skill primary care providers in triage evaluation, and management options as well as to inform patients of care pathways.

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MANAGEMENT APPROACHES

A triage system may identify individuals with good, moderate, and poor prognoses and identify their presenting features, but outcomes will not improve unless management approaches can effectively address these features and restore the individual's functional status. No management approach has substantively lessened the incidence of transition to chronicity. There is debate on fundamental issues such as whether whiplash should be regarded and managed as a medical problem (i.e., a musculoskeletal injury) or whether psychosocial, health care, and societal factors are dominant in WAD leading to the recommendation that early management should be nonmedicalized.30,31 Appropriately designed prospective research (e.g., diamond design)32 could investigate this fundamental issue of comparative effectiveness of early medicalized or nonmedicalized management approaches and simultaneously answer questions of the beneficial or iatrogenic effect of early versus delayed active intervention (i.e., no early medical intervention).

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Interventions

The early management of whiplash-injured individuals has largely been within a traditional medical model. Rates of transition to chronicity have remained stable over several decades, regardless of intervention.3,4,33,34 Lesions of zygapophysial joints after a whiplash injury have received most attention in basic, applied, and clinical research3537 and can be identified in vivo with invasive diagnostic procedures.35 However, it seems that lesions can potentially occur to any cervical structure,38 but there are currently no validated tools to identify or negate their presence in patients. Future research is important to determine the value of detection of sources of nociception to test a hypothesis that targeted preventive and treatment strategies of the injuries affect the outcome of whiplash.

Management is largely based on presenting clinical features. A question is whether current early management methods are optimal and whether improvement in their construction, delivery, and timing of delivery (early or later) could reduce the transition to chronicity. We see future research needs in four areas: education, pain management, physical rehabilitation, and psychological intervention in line with the pain syndromes, physical, and psychological responses documented in association with whiplash. This is an artificial separation as interventions overlap. Evidence of the potential for certain interventions to dominate at specific time points is emerging and will increase rapidly as research reveals pathophysiological and psychological interactions, drivers, and modifiers of symptom complexes presenting in the whiplash-injured individual.5,8,39,40 Importantly, any intervention must consider patient acceptability and preference and cause no harm.41

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Education

Any search in the Internet quickly reveals a large amount of information about whiplash, its mechanisms, management, and, occasionally, its potentially dire effects. The quality of information available for consumers is highly variable and some are potentially destructive. Information, assurance, and education are important aspects of patient management. Whiplash information booklets, Web sites, and videos have been developed4245 and tested for patient comprehension and acceptability,46 but education alone has not been shown in good- to high-quality trials to reduce the transition to chronicity.47,48 Currently, there appears to be wide variability in the nature of information and advice provided to a patient, suggesting that best information or education approaches as well as strategies for behavior change and system change are yet to be established.4951

In a patient-specific context, the impact of providing prognostic information about whiplash recovery should be explored with mixed-methods research. Information is required on the positive or negative impact on recovery rates, coping skills, psychological distress, treatment compliance, and costs if patients were fully informed in a nonalarmist manner about prognoses and different recovery paths in the early stages of their disorder. The question is whether stratification of advice according to recovery pathways has beneficial or iatrogenic effects; that is, does knowledge of allocation to a poor recovery group increase the likelihood of a poor recovery, or does it increase treatment compliance toward improving outcome?

Best methods to provide information to positively influence patient behavior/outcome require investigation in a whiplash context. Preliminary evidence shows that education delivered face-to-face has benefit over a pamphlet,48 but in this era of technology and time-pressured lifestyles, Internet-based options may be a preferred and successful method.52 Trials of acute whiplash have involved provision of formal information and education on a single occasion with limited effect on outcome.45,47,48 The effects of reinforcement of education and advice and opportunities for discussion/problem solving on outcomes requires investigation. Any research into knowledge translation should consider the construct of an education intervention including the type of learner cluster (relationship of instructor to learner), the medium, the technique used, pedagogical characteristics, the type of follow-up, and behavior change principles. The area could be well informed by the experiences of implementation of self-management in other domains.53 It will be essential to understand patients’ preferences for content of information, methods of delivery, and overall management approaches. As the nature of messages provided to the individual with whiplash in the initial consultation and early period may be potent determinants of their ensuing trajectory, a necessary component of translational research will be education for primary care providers for optimal education and communication with the patient in a trauma and compensation environment.

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Pain Management

Current evidence suggests that the pain of many patients with acute whiplash can be managed successfully with a combination of education, physical treatments such as activation, manual therapy, and gentle exercise.6 Some trials have used simple analgesics and/or nonsteroidal anti-inflammatory drugs as a cointervention with physical treatment, but it is questioned whether an emphasis on pain management for those with initial moderate to high pain levels and at risk of moderate to poor prognoses could improve outcomes and reduce the rate of transition to chronicity. There has been little dedicated research into pharmaceutical management of pain of acute whiplash6 and, in general, pain management guidelines lack any concerted focus on management of moderate to severe acute musculoskeletal pain states.54 One preliminary study investigated the use of a methylprednisolone infusion versus a placebo control55 in the management of acute whiplash (within 8 hours of injury). Outcomes were positive in terms of disabling symptoms and time off work. However, this work has not been pursued.

Future research into acute pain management strategies for patients with moderate to high pain levels relies on the development of knowledge of early neurobiological processes underpinning higher pain levels to establish models on which pharmaceutical or other interventions for pain management can be tested. The mooted hypothesis is that correction of these processes would lead to better outcomes. Such evidence would also help to validate models that propose a role of neurobiological processes in determination of patient outcome. Pettersson and Toolanen55 postulated an inflammatory model to test their intervention of a methylprednisolone infusion. High levels of pain in association with cold hyperalgesia are a strong predictor of poor outcome,4,8,13 suggesting a need for interventions to address central pain processing or, in some cases, a neuropathic pain state. In addition, there is growing evidence of a relationship between stress response systems and central pain processing39,56,57 with possible genetic predisposition.39 This may open new avenues for research into pharmaceutical or multimodal multidisciplinary management. Trials of drug management for pain in whiplash, especially those with initial moderate and high pain levels, are required to determine effects on long-term outcomes. Major considerations that need to be incorporated in any studies on pharmaceutical interventions for pain in whiplash include risk/benefit analysis of potential adverse side effects, the possible role of psychological profiling of patients for these interventions, as well as consideration of patient preference and compliance.

Early effective pain management for those with moderate or poor prognosis is deemed one of the more important areas for future research to reduce the transition to chronicity. In addition to inevitable psychological sequelae of high-level and persistent pain, pain will challenge the patients’ functional capacity and physical rehabilitation with adverse consequences on neuromuscular function.5862 It has been shown, albeit in a chronic whiplash population, that the outcomes of physical rehabilitation were marginal in those patients who reported higher levels of pain associated with widespread mechanical and cold hyperalgesia.63 Outcomes were substantively better in patients without this sensory presentation. As the presence of widespread mechanical and cold hyperalgesia has been documented in patients with high pain levels soon after a whiplash injury,23 it is reasoned that early implementation of effective pain management for those with early moderate to high pain levels is critical in attempts to lessen the transition to chronicity. Trials are required to test the effects of improved pain management on physical and psychological features, the rehabilitation process, and long-term outcomes.

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Physical Rehabilitation

Studies have demonstrated the potentially widespread physical responses, which can present in association with the neck pain, headache, feelings of dizziness, unsteadiness, and restricted function that patients may report after a motor vehicle crash. Physical responses include sensory disturbances (local or widespread), restricted neck motion, and an array of disturbances in neuromuscular and sensorimotor control.18,19,24,6469 There is often coexisting pain and dysfunction in the thoracic and low back regions.70 Most clinical trials for acute whiplash have evaluated physical rehabilitation approaches.6 However, interventions are heterogeneous and have been composed of various configurations of exercise and manual therapies. Although trials have provided evidence of benefit of these physical therapies for many patients, the incidence of transition to chronicity persists. Increasing knowledge of neurobiological and psychosocial features in whiplash points to several priorities in future clinical trials, toward improving rehabilitation outcomes.

In relation to trial design, clinical trials for acute whiplash have treated whiplash cohorts as homogenous populations, despite heterogeneity in presentation and a range of recovery paths. The presence or not, and the magnitude of disturbances across physical domains, is variable whether considering sensory features, movement abnormalities, or disturbances in neuromuscular and sensorimotor systems. A case can be argued for treating patients pragmatically on the basis of presenting features with management pathways matched to the individual. Management pathways will likely range from simple minimal intervention for more minor, noncomplex presentations to more concerted multiprofessional/multimodal interventions for more major, complex presentations. Future clinical trials should consider more individualized interventions in association with triaging or subgrouping of patients to determine whether this approach enhances outcomes and lessens the rate of transition to chronicity.

In relation to interventions, the current heterogeneity in interventions is of concern and future interventions need to be research informed toward improving outcomes. Much more is now known of the neuromuscular and sensorimotor disturbances accompanying WAD, which can inform new and innovative rehabilitation approaches. Not unexpectedly, evidence is emerging that exercise approaches specifically designed to deal with particular neuromuscular and sensorimotor disturbances appear to be more effective in addressing these features than generic exercises.7173 The outcomes of more specifically designed and targeted exercise against general exercise need to be evaluated, particularly in relation to lessening the transition to a chronic or recurrent disorder. Other issues require consideration in the development of exercise programs. Most types of exercise have pain-relieving effects,74 and pain scales and questionnaires are the most common primary outcome measures used in clinical trials. Physical function measures are often included as secondary or tertiary outcomes, but the importance of full restoration of neuromuscular and sensorimotor function and its relationship to the transition to chronicity is unknown. Further research is needed to test the impact of restoration of neuromuscular and sensorimotor function on long-term outcomes. In this light, Teasell et al6 observed that dosages of exercise in the clinical trials seemed to be provided in an arbitrary manner, which is a fundamental issue. There is a critical need for further physiological research to inform future clinical trials on the nature and dosages of exercise required to retrain the various neuromuscular and sensorimotor disturbances.

Methods and timing of delivery of physical rehabilitation and cointerventions also require attention for acute whiplash, given the heterogeneity across biopsychosocial domains. High initial pain is a strong predictor of poor outcome and an initial emphasis on maintenance of activity14,10,12 and physical rehabilitation may be inappropriate or, at worst, have detrimental effects in such individuals. Pain management may need prioritization in this case. With respect to activity and physical rehabilitation, the effect of delaying rehabilitation or conversely, the optimal timing for physical rehabilitation for patients with acute moderate to severe pain, requires examination.

Patients’ individual traits and psychological features can also modulate the pain experience and influence the rehabilitation process.8,14,75 The effect on outcomes of managing issues such as self-efficacy, coping skills and expectations, and anxieties and fears by delivering rehabilitation within a behavioral context needs to be evaluated. Patient preferences in management can affect treatment compliance and outcomes41 and modes of delivery need to be considered in development of innovative management options.

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PSYCHOLOGICAL REHABILITATION

Several psychological responses may present in the whiplash-injured patient. It is recognized that individual traits such as coping skills, self-efficacy, and psychological responses, for example, fear-avoidance beliefs, catastrophization, depression, expectations, and perceived injustice can amplify or modulate the pain experience and influence recovery trajectories. Stress responses may contribute to the pain experience through neurobiological mechanisms. Symptoms of post-traumatic stress disorder (PTSD) have been documented in acute whiplash and there is evidence that early, elevated scores on questionnaires for PTSD symptoms are associated with poor prognosis. The management of psychological features is ripe for research. Although psychological features have been recognized, there have been no studies investigating the effectiveness of early psychological interventions applied in the management of acute whiplash on recovery nor on the transition to chronicity.

The research agenda for the management of psychological responses and clinical trials of the impact of such management on lessening the incidence of transition to chronicity has several priorities. First, the compensation environment of whiplash and patient issues such as validation of their condition suggests that formal assessments of psychological features in the acute stages of the disorder may need careful timing to avoid patient antagonism. Second, many clinical trials use an assessment at a single time point of psychological state, which is not sufficiently informative to prescribe a formal psychological intervention, because of the typically remitting course of psychological distress. Rather the prescription of any intervention should be guided by how the psychological status does or does not change over time and this needs to be taken into account in future trial designs.

Best practice methods for managing psychological modulators of pain in management of acute whiplash need to be developed. For example, there could be value in developing a cognitive-behavioral therapy program for parallel management of catastrophization, fear-avoidance beliefs, and self-efficacy. Specific cognitive change approaches that address beliefs of perceived injustice are yet to be developed. Work has been done on the early intervention for acute stress disorder,76 some with specific motor vehicle crash populations, but this has not been integrated into specific whiplash management. Cognitive-behavioral therapy for the treatment of PTSD has been piloted with patients who have chronic whiplash.77 However, it is unclear whether this management is effective in the context of acute whiplash. Although it may be advantageous to recognize and target those with early stages of the disorder, there is some evidence that if certain types of early psychological intervention are applied, the outcomes are less than optimal.29 Appropriate timing of early psychological intervention is by no means clear. However, a period of 4 weeks has been suggested as a waiting period before any formal psychological intervention.78 This timeframe coincides with the minimum duration post-trauma required before a diagnosis of PTSD is possible. However, this approach is yet to be validated. Clinical trials are needed to test the timing and effectiveness of early management of post-traumatic stress on outcomes of pain and function in addition to psychological status.

Many initial psychological responses can change and be influenced by other treatment effects; for example, fear avoidance and anxiety have been shown to decrease in parallel with reduced pain and disability.79 However, it might be useful to directly intervene for some psychological features during the acute postinjury period. A related issue is which care provider(s) is/are best placed to deliver intervention for psychological modulators of pain in the immediate postwhiplash period. It may not be ideal to defer all psychological intervention to an external psychologist when the patient has chosen to come under physical care. The psychologist might better be included as part of a care team to provide consultation as needed and supervision, if necessary, for the primary care provider. A future research direction to explore is whether patients’ psychological responses can be effectively managed by primary care providers trained in the use of specific cognitive-behavioral therapy techniques with a specialist psychologist working as a consultant with the primary care provider. An exception would be patients with symptoms suggestive of a psychiatric diagnosis such as PTSD, anxiety disorder, or major depressive disorder.

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FUTURE DIRECTIONS IN RESEARCH FOR THE PREVENTION OF THE INJURY

Prevention of injury is the ideal. Clinical, epidemiological, and biomechanical research conducted over the past 20 years has effectively identified injury mechanisms and injured tissues during low-velocity automotive rear impacts. This research has led to the incorporation of head restraints and, more recently, active head restraints that reduce the loads sustained by cervical spine tissues during these events.8083 However, despite these advances, whiplash injuries continue to occur and patients continue to sustain chronic symptoms.84 Epidemiological studies have identified specific populations that may have an elevated risk of injuries. Moreover, some have warned us about the possibility of creating iatrogenic disability.30,85 For example, occupant-related factors including sex, age, and awareness of impending impact have all been reported to influence injury outcomes in automotive rear impacts.16,86,87 Likewise, head restraint and seat positioning at the time of impact can influence injury risk. Future clinically and experimentally based research should focus on defining population characteristics and specific attributes that contribute to greater risk of soft-tissue injury or enhanced symptoms. For example, a number of biomechanical studies have identified greater cervical spine motion and soft tissue distortion in women during simulated rear impacts. However, a basic understanding of the mechanism underlying increased motion in women has not yet been defined. Greater motion could result from increased soft tissue elasticity, more slender cervical columns, smaller body size, or decreased neck muscle force-generating capacity. The direct influence of these factors on the dynamic biomechanics of the cervical spine during rear impacts has not been well defined.

Laboratory-based postmortem human subject experimentation will continue to play a role in understanding the biomechanics of injury tolerance during automotive rear impacts as these surrogates provide the most realistic model of human response. However, advances in computational modeling have progressed the field of biomechanics by providing a cost-effective alternative. Statistically based finite element models may improve understanding of injury tolerance by providing a probabilistic outcome as opposed to a deterministic solution. A hybrid approach incorporating postmortem human subject experimentation and comprehensively validated and verified finite element models may be the most appropriate protocol to parametrically study the influence of occupant and crash-related factors on injury outcomes during automotive collisions. Likewise, a basic understanding of subfailure tissue tolerance and its correlation to nociception are required as inputs for computational models to define injurious conditions. Traditional catastrophic tissue tolerances are not appropriate for the study of whiplash injuries as these rarely induce complete tissue failure. Injuries and chronic pain in whiplash-injured patients are more likely the result of tissue strain exceeding the threshold for nociceptor activation. Once strained beyond the physiologic limit, subfailure tissue injuries may be aggravated with continued postinjury movements and this may lead to chronic pain. Continued research focus in these areas, both basic and clinically applied, can provide a comprehensive understanding of the mechanical aspects of whiplash injuries on a more fundamental level and lead to more effective automotive countermeasures to protect all occupants during automotive rear impacts.

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CONCLUSION

Effective early management is a core ingredient to meet the challenge of lessening the rate of transition to chronicity for the acute whiplash-injured individual. At present, no management or preventative method has fully conquered this challenge and fundamental questions relating to basic philosophies of medicalization and nonmedicalization of the disorder persist. The field requires further dedicated research. The outcomes of discussions of an international multidisciplinary meeting have identified research priorities across the biopsychosocial spectrum toward optimization of the management of whiplash in the acute phase with the aim to lessen the incidence of chronicity.

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Key Points

  • Acute whiplash presentations are heterogeneous, suggesting triage to inform diagnosis, and individualized management decisions are important.
  • Development of optimal pain management is urgently required for individuals presenting with moderate to high pain levels.
  • Research informed that rather than arbitrarily delivered education/information, physical and psychological rehabilitation is required.
  • Research is required on the occurrence of tissue damage and its prevention.
  • Future high-quality clinical trials are needed to test the impact of new strategies on the rate of transition to chronicity.
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      Keywords:

      acute whiplash; cervical spine; management

      © 2011 Lippincott Williams & Wilkins, Inc.