Physical and psychological aspects of whiplash
Physical and psychological aspects of whiplash: Important considerations for primary care assessment
From: Manual Therapy. Volume 13, Issue 2, Pages 93-102 (April 2008)
Whiplash is a heterogenous and in many, a complex condition involving both physical and psychological factors. Primary care practitioners are often the first healthcare contact for individuals with a whiplash injury and as such play an important role in gauging prognosis as well as providing appropriate management for whiplash injured patients. It is imperative that factors associated with poor outcome are recognized and managed in the primary care environment at the crucial early acute stage post injury. This paper outlines the heterogeneity of the whiplash condition in terms of both physical (particularly the sensory presentation) and psychological characteristics and the relationships between these features. The clinical assessment of these factors will be explored as well as direction for appropriate early interventions. An early co-ordinated inter-professional management approach, particularly in patients with a complex clinical presentation involving central hyperexcitability and symptoms of posttraumatic stress will be required.
The development of persistent pain and other symptoms following whiplash injury during a motor vehicle crash is common. Whilst it has generally been stated that only a minority of injured individuals will make the transition to chronic pain and disability, recent Australian data indicate that the prognosis may not be so favourable. In these studies approximately 60% of people continued to report pain and associated disability 6 months and 2 years after the original motor vehicle crash. Whiplash is a significant public health problem with most of the social and financial burden arising from those who develop chronic pain and disability.
Whiplash is a heterogenous condition. The presence of certain physical and psychological characteristics (hyperalgesia, movement loss, posttraumatic stress symptoms, moderate/severe levels of pain and disability) demonstrates a complex clinical picture in some. This clinical presentation reflects multifaceted mechanisms underlying whiplash pain, including augmented central pain processing mechanisms in association with posttraumatic stress. The early presence of these factors is predictive of poor functional recovery from the injury. This suggests that early intervention comprising management options to address these factors may be necessary in order to prevent the transition to chronic pain and disability in ‘at risk’ patients.
Primary care practitioners are often the first healthcare contact for individuals with a whiplash injury. An important role for clinicians is to not only provide ‘treatment’ but also to attempt to gauge the prognosis for the patient. This will alert the clinician that a more concerted approach to management may be necessary, one that could involve input from other health care providers. Should such an approach be deemed appropriate then the primary care clinician should aim to co-ordinate care between the various professionals involved in the patient’s management. It is imperative that factors associated with poor outcome are recognized and managed in the primary care environment at the crucial early acute stage post injury. Musculoskeletal clinicians play an important role in this regard.
Motor and sensori-motor dysfunction, including movement loss, altered cervical and shoulder girdle muscle recruitment patterns, kinaesthetic deficits and balance loss have been identified in both the acute and chronic stages of the whiplash condition .
Most of the motor deficits are present to various degrees in whiplash injured individuals irrespective of pain and disability levels and level of recovery. Additionally, these features may not be unique to whiplash and have also been identified in chronic neck pain of insidious (non-traumatic) onset. Furthermore, treatments directed at rehabilitating motor dysfunction and improving general movement show only modest effects on pain and disability. Together these findings suggest that motor deficits, although present, may not play a key role in the development of chronic symptoms following whiplash injury. This is not to say that treatment directed at ameliorating motor dysfunction should not be provided to whiplash injured people. Rather that the identification of such impairments may not equip the clinician with useful information on either prognosis or treatment responsiveness.
In contrast to the apparently uniform presence of motor dysfunction, the sensory presentation is a feature that differentiates whiplash from less severe neck pain conditions and whiplash sub-groupings. There is now consistent evidence of sensory disturbances indicative of central nervous system hyperexcitability as an important feature of some whiplash injured people.
The presence of central hyperexcitability is not unique to whiplash, with other painful conditions including fibromyalgia, tension-type headache and migraine also manifesting such signs. However, it is not a phenomenon universal to all musculoskeletal conditions or to all forms of neck pain. Scott et al. recently showed that insidious onset chronic neck pain demonstrated a very different sensory presentation. The hyperalgesia of this neck pain group was confined locally to the cervical spine with no widespread hypersensitivity that would indicate more profound central nervous system changes. Whiplash sub-groups can also be identified based on their sensory presentation. A sub-group with widespread sensory hypersensitivity indicative of central hyperexcitability can be identified from very soon after injury and it is this sub-group who show poor functional recovery. The other whiplash injured participants in this study showed a similar presentation to insidious onset neck pain—that is the presence of local cervical hyperalgesia with little evidence of more widespread changes. It is not clear why some people appear to develop central hyperexcitability following whiplash injury but there is a relationship between this phenomena and reported levels of pain and disability.
Recent evidence suggests that the clinical identification of central hyperexcitability is important. This is for two reasons, firstly some of the sensory features, particularly cold hyperalgesia and intolerance are predictive of poor functional recovery and secondly the combined presence of mechanical and cold hyperalgesia in chronic whiplash moderates the effects of physiotherapy treatment. In this study a 10-week physiotherapy programme of assurance, advice, specific exercise and manual therapy, was not effective in decreasing pain and disability in people with chronic whiplash and mechanical and cold hyperalgesia. The same treatment approach in the patients without this sensory presentation led to clinically significant reductions in pain and disability.
The psychological presentation of whiplash can be as equally diverse as the physical presentation. There is no doubt that persistent whiplash pain is associated with psychological distress including affective disturbances, anxiety, depression and behavioural abnormalities such as fear of movement. Psychological distress is also present in the acute post-injury stage with most people showing some distress regardless of symptom levels. Persistent psychological distress is likely associated with ongoing or non-resolved pain and disability. A recent large cross-sectional study showed an association between anxiety, depression and pain and disability in people whose accidents occurred over two years previously, but not in those with acute injury, suggesting that symptom persistence is the trigger for psychological distress. Longitudinal data indicate that initially elevated levels of distress decrease in those who recover, closely paralleling decreasing levels of pain and disability.
It is emerging that unique psychological factors may be involved in the aetiology and development of chronic whiplash pain. The role of fear of movement beliefs seems to be a less important factor in whiplash than in low back pain. The role of coping styles or strategies in whiplash is unclear. Some data indicate that a palliative reaction (e.g. seeking palliative relief of symptoms such as distraction, smoking or drinking) was associated with longer symptom duration. In contrast Kivioja et al. found no evidence that different coping styles in the early stage of injury influenced the outcome at 1-year post accident. The different cohort inception times of these studies may account for the differences in findings indicating that coping strategies may vary depending on the stage of the condition and this requires further investigation.
Whiplash injury differs from most other musculoskeletal pain syndromes in that it is generally precipitated by a traumatic event, namely a motor vehicle crash. The effect of the psychological stress surrounding the crash itself as opposed to distress about neck pain complaints may have an influence on outcome. Posttraumatic stress disorder is a common sequalae of severe injuries following a motor vehicle crash. Yet, it is only recently that evidence has emerged to show that it may also play a role in less severe road accident injuries including whiplash.
Posttraumatic stress disorder has been diagnosed in some patients with chronic whiplash associated disorders. In addition a moderate/high acute posttraumatic stress reaction (measured with the Impact of Events Scale—IES) is present in some whiplash injured individuals soon after injury. The presence of posttraumatic stress symptoms has been shown to be associated with more severe whiplash complaints and poor functional recovery and is a stronger predictor of poor outcome than both general psychological distress and fear of movement/reinjury. For the clinician it may be useful to consider psychological distress following whiplash injury as involving both event (motor vehicle crash) related distress and distress associated with neck pain that contribute to persistent pain and disability.
posttraumatic stress symptoms may include intrusive thoughts and/or images of the event (in this case the motor vehicle crash); avoidance behaviour associated with the event such as driving avoidance or via substance abuse; hyperarousal such as panic attacks, hypervigilance and sleep disturbance. Yet it is not clear if any of these symptoms play a specific or greater role than the others in the development of whiplash pain, disability or related adverse health outcomes. Sterling et al. showed that avoidance behaviour may have a stronger influence on recovery and Buitenhuis et al. showed that hyperarousal symptoms in the acute stage were a stronger predictor of symptom persistence. Further investigation is required to determine the relative importance of the substrates of posttraumatic stress as this may provide fruitful direction in terms of specific psychological approaches to whiplash management.
The biopsychosocial model considers pain and disability as the consequence of multiple factors, with biomedical (physiological/physical) and psychological factors intimately intertwined. However it is not clear what the relative role of each factor may be or how they interact. Anecdotally at least, clinicians would be aware of patients who fail to adequately respond to physical interventions until their psychological distress is addressed. Perhaps the continued distress exerts an influence on the physical presentation of the patient that is difficult to manage via physical means alone. There is data available to support such clinical observations. A multimodal physiotherapy programme whilst decreasing distress in some patients with chronic whiplash showed minimal benefit in patients with mechanical and cold hyperalgesia and moderate symptoms of posttraumatic stress . It is possible that the physical and psychological interactions occurring in such patients are too complex to be addressed by physical treatment alone. The exploration of the relationships between physical and psychological factors could assist in determining the nature and timing of various intervention forms.
Models have been recently proposed in an attempt to provide a basis for the complex interrelationships between physical and psychological aspects of the whiplash and other conditions. It has been suggested that the dysregulation of neurobiological pain processing (central hyperexcitability) is related to the stress response and/or sympathetic activation in the early stages following injury and this interaction may be a critical step in the development of persistent pain. Stress system dysregulation has also been described in posttraumatic stress disorder, a factor that occurs concurrently with central hyperexcitability in some whiplash injured people. Passatore and Roatta go further and outline an argument in which sympathetic activation that occurs via stress can influence motor and sensori-motor function in addition to contributing to pain processes. These authors argue that increased sympathetic outflow (via stress) leads to excessive vasoconstriction which in turn may impair muscle microcirculation and cause structural muscle changes; muscle fatigue and effects on muscle spindles leading to proprioceptive deterioration. Whilst data on blood flow to muscles in whiplash associated disorders are not available, sympathetic vasoconstrictive changes in peripheral skin, morphological muscle changes and proprioceptive deficits are present. The links, if any, between these characteristics of whiplash are not yet known but it poses interesting possibilities of the influence of psychological factors on the physical manifestations of this condition. In fact, the co-occurrence of these myriad of factors in some (but not all) of the whiplash injured has led to calls to regard the condition as a systemic type illness.
Nevertheless, there has been some investigation of relationships between the psychological and physical presentations of whiplash associated disorders. Sterling et al. demonstrated moderate associations between cold pain thresholds and both psychological distress (GHQ-28) and catastrophisation (Pain Catastrophising Scale). Notably there was no relationship between catastrophisation and the intensity of electrical stimulation required to elicit a flexor withdrawal response in biceps femoris in the same patient group. The latter test is a measure of spinal cord hyperexcitability requiring no cognitive response from the participant. These findings indicate that psychological factors play a role in the sensory presentation of whiplash but do not support the assumption that psychological factors are the only or main factors responsible for central hyperexcitability. In particular, spinal cord hyperexcitability appears not to be affected by the psychological factors that were assessed. The clinical relevance of these findings suggests that both central hyperexcitability and psychological factors will require consideration in the management of whiplash.
Relationships between sensory disturbances and posttraumatic stress symptoms have also been explored. The early presence of sensory hypersensitivity was associated with persistent (6 months) posttraumatic stress symptoms but this relationship was mediated by initial pain and disability levels. In contrast, early sympathetic disturbance (impaired peripheral vasoconstriction) was associated with persistent posttraumatic stress symptoms and showed no relationship with initial pain and disability levels. Although speculative, this may be an indication of a biological vulnerability that may trigger persistent posttraumatic stress and is an area of debate. For clinicians it may indicate that patients with higher initial pain and disability levels and/or evidence of sympathetic disturbance could be at risk of persistent posttraumatic stress symptoms and this should be considered in their management.
Sensory hypersensitivity (cold and mechanical hyperalgesia) within one month of injury was associated with persistent posttraumatic stress symptoms (posttraumatic stress symptoms) at 6 months postinjury but this relationship was mediated by pain and disability levels (Neck Disability Index—NDI). Impaired vasoconstriction measured within 1 month of injury was associated with persistent posttraumatic stress symptoms but was not related to NDI scores.
One of the aims of whiplash management is to improve movement or activity levels and to decrease pain. Indeed, there is strong evidence that the maintenance of activity and exercise are efficacious approaches in both the acute and chronic stages of the condition. A possible hindrance to patients achieving goals in regard to activity and exercise may be related to their perceived fear of pain and/or movement and this is usually recognized by clinicians. By using unique methodology of ambulatory physiological data collection methods where participants wear (for 1–2 days) a device that collects physiological data in conjunction with electronic pain diaries we have been able to explore these relationships. Preliminary data indicate that high levels of posttraumatic stress symptoms, in particular avoidance symptoms, were more strongly associated with less daily activity than high fear avoidance beliefs. The avoidance scale reflects efforts to avoid thoughts, feelings and situations associated with the motor vehicle crash rather than neck pain, so it is interesting that it was associated with behavioural withdrawal from physical activity. General activity levels were measured in this study and it is not yet clear if the influences of stress symptoms will extend to effects on the patient’s execution of prescribed exercises. Nonetheless, these findings suggest that it will be important for clinicians to identify posttraumatic stress symptoms not only to institute possible psychological referral, but also to ensure that all potential hindrances to improve movement/activity levels and restore function are considered.
