Chapter 8 Psychological aspects of whiplash associated disorders

Jan Buitenhuis, Peter de Jong, Jan Jaspers, Justin Kenardy

This chapter provides an overview of current scientific knowledge regarding psychological determinants of whiplash associated disorders (WAD) and the possible relationship with aetiology, symptom severity and course.

A distinct characteristic of whiplash injury, or WAD, when compared to other chronic pain conditions, is the relationship to an accident. As a consequence, there is usually a sudden onset of symptoms. Furthermore, in many cases the accident is caused by someone else, which can lead to negative feelings towards the responsible party. The latter situation can also lead to a liability claim, which could further influence the course of symptoms.¹

Dealing with an accident requires certain emotional and stress management skills. The onset of acute or post-traumatic stress symptoms can influence the experience of symptoms and, thus, their course. Neck pain can be named or labelled in several ways. This process can lead to or be the result of anxiety, dysfunctional beliefs and negative expectations regarding the experienced symptoms.

In research on low back pain, it is well established that psychological factors are related to chronic pain and disability.² Given that chronic whiplash is also chronic musculoskeletal pain related to the spine without clear identification of a somatic cause, it seems reasonable to hypothesise that psychological parameters may play a role in the aetiology and course of persisting whiplash symptoms. Although a recent review of predictive factors for developing chronic whiplash complaints revealed only limited evidence for psychosocial variables, such as personality traits and psychosocial work factors, there is evidence that psychological distress, including affective disturbances, anxiety and depression, are associated with persistent whiplash symptoms.³^–⁵ It is becoming apparent that psychological factors, such as initial and persisting post-traumatic stress, may be involved in the aetiology and maintenance of chronic whiplash symptoms.⁶ Identification of these and other psychological factors is, therefore, of paramount importance in the facilitation of prevention and/or treatment.

Accident-related psychological factors

Acute and post-traumatic stress disorder

An important factor to consider is that neck complaints in whiplash follow an accident. An accident can be a frightening and sometimes even a terrifying experience. It is, therefore, not surprising that such an experience often gives rise to post-traumatic anxiety symptoms. Experiencing a traumatic event can also lead to the onset of a so-called acute stress disorder (ASD). The essential features of ASD are the development of anxiety, dissociative and other symptoms that occurs within one month after exposure to an extreme traumatic stressor.⁷ Following the American Psychiatric Association’s DSM IV classification, the specific diagnosis requires several criteria, including derealisation, depersonalisation or dissociative amnesia where an important aspect of the trauma cannot be recalled; recurrent images, thoughts, dreams, illusions or flashback episodes; marked avoidance of stimuli that arouse recollections of the trauma; and marked symptoms of anxiety or increased arousal. These symptoms cause clinically significant distress or impairment in social, occupational or other important areas of functioning.⁷ Also, when the formal diagnostic criteria are not met, there can obviously still be acute stress symptoms. Although research on early stress symptoms (< one month) in whiplash is rather scarce, the available evidence suggests that there is a moderate-to-severe acute stress response in about 13% of whiplash cases.⁸ Thus far it is largely unclear if acute stress symptoms are associated with whiplash symptom severity or have any predictive value regarding recovery.

Stress symptoms that persist for more than one month may eventually evolve into post-traumatic stress disorder (PTSD). PTSD is an anxiety disorder that requires a response of fear at the time of trauma together with three symptom clusters: re-experiencing, avoidance and hyperarousal symptoms. PTSD is a relatively common condition following traffic accidents.⁹^–¹² As many as 23% of traffic accident victims develop PTSD, which is known to have high psychiatric and medical comorbidity.¹³^–¹⁶ Post-traumatic stress symptoms may give rise to increased anxiety and vigilance levels, thereby fuelling catastrophic, dysfunctional interpretations of acute neck pain. PTSD shares several symptoms with whiplash, including sleep disorder, irritability and problems with attention and concentration. Therefore, it is also conceivable that post-traumatic stress symptoms may be erroneously attributed to whiplash.

There is evidence to indicate that post-traumatic stress symptoms (i.e. re-experiencing and avoidance symptoms) are related to whiplash.^6,¹⁷ More specifically, the re-experiencing and avoidance subscales of the Impact of Event Scale (IES) were found to be associated with relatively persistent whiplash complaints at six months follow-up.¹⁸ Unfortunately, many studies use the IES, thereby only testing two of the three PTSD symptom scales; the hyperarousal symptom cluster scale is not included in the IES. Nonetheless, other research has shown hyperarousal symptoms to be highly relevant in the relationship between PTSD and whiplash.¹⁹

Since anxiety is an important feature of PTSD and is known to influence the perception and experience of pain, post-traumatic stress symptoms may also alter the perception and experience of acute neck pain.^20,²¹ It has been shown that PTSD is more prevalent among car-accident victims who have post-whiplash syndrome compared to car-accident victims experiencing other symptoms. Moreover, the presence of PTSD is associated with more severe post-whiplash symptoms.^6, ^{17, 19} Additionally, the hyperarousal symptoms cluster has been found to have predictive validity for the persistence and severity of post-whiplash symptoms six and 12 months after the accident.¹⁹ This predictive validity cannot be readily attributed to either the severity of the accident or the severity of the sustained injury, as these aspects have been found to be largely independent of the development of PTSD.²² This seems to correspond with earlier research that suggests that victims with post-whiplash syndrome generally considered the accident more frightening than did other car-accident victims, suggesting the presence of higher fear levels, which in turn may elicit or indicate post-traumatic stress.²³

Because perceived threat is of paramount importance in the aetiology of PTSD, it can be hypothesised that the presence of whiplash complaints is threatening and induces anxiety complaints. This would make the accident even more frightening and could subsequently lead to more post-traumatic stress symptoms. The presence of PTSD was found to be associated with more severe whiplash complaints and poor functional recovery.^6,¹⁹ Results from research on the specific relevance of the three symptom clusters is still ambiguous. One study found that avoidance behaviour may have a stronger influence on recovery.⁶ In another study, which controlled for all three symptoms clusters, only the hyperarousal cluster was found to have predictive validity.¹⁹ Hyperarousal symptoms also include hypervigilance, which is known to be correlated with higher reported pain intensity and catastrophic thinking.²⁴ Therefore, it could be that hypervigilance results in symptom amplification, fuelling perceived symptom severity, thereby contributing to a process that leads to chronic complaints.

In the sympathetic arousal hypothesis, hypervigilance is labelled as sensory hypersensitivity. There is consistent evidence of sensory disturbances indicative of central nervous system hyperexcitability as a characteristic of whiplash. Studies have shown lowered pain thresholds and pain tolerance to various stimuli. Specific sensory features, such as cold hyperalgesia and intolerance, seem predictive of poor functional recovery.^25,²⁶ Early sympathetic disturbance was found to be associated with persistent post-traumatic stress symptoms, leading to speculation of a biological vulnerability that may trigger persistent post-traumatic stress.²⁷ All in all, studies from several directions point to a mechanism characterised by hyperarousal, hypervigilance or nociceptive sensitisation related to the prognosis of whiplash symptoms.

It is important to note that within PTSD, hyperarousal symptoms closely resemble symptoms that are often attributed to post-whiplash syndrome, such as difficulty concentrating or nervousness. It is, therefore, conceivable that these symptoms often associated with whiplash are actually related to post-traumatic stress. It is also possible that the predictive value of hyperarousal symptoms is merely due to these symptoms resembling symptoms associated with or often attributed to post-whiplash syndrome. The intensity of these symptoms is known to be related to a poor prognosis.

Anger and blame

Whiplash is, by definition, preceded by an accident. In many cases an accident may have an external cause, involving another person or persons. Feelings of anger towards those perceived to be responsible are often expressed in clinical practice. Furthermore, it has been argued that chronic whiplash symptoms seldom present in drivers who have caused the collision. Therefore, attributed blame may be associated with the prognosis.²⁸ It has been demonstrated that perceived responsibility for a traffic accident was associated with lower PTSD levels six months after the accident.²⁹ Research in other chronic pain conditions has shown that anger is associated with heightened pain expression.³⁰ In whiplash, anger was found to be associated with physical and psychological complaints six months after a motor vehicle crash (MVC).³¹ In summary, research suggests that anger is an emotion that can influence the experienced pain and is associated with persistent symptoms. This is especially so in the context of legal liability.

Coping

Coping can be defined as the way in which an individual behaviourally, cognitively and emotionally adapts to manage external or internal stressors.³² The accident itself, as well as the pain afterwards, can be considered an external stressor and, therefore, requires coping efforts. Research in the context of chronic low back pain showed that individuals’ coping style is an important moderator of the course of pain symptoms and the outcome of treatment.^33,³⁴ Because in whiplash the onset of complaints is often related to a stressful accident, this may place an even higher demand on existing coping skills. Accidents can lead to physical complaints or to temporary or long-term disability, all demanding satisfactory coping.

The experience of neck pain may be more frightening than low back pain, which, while more common, is usually believed to be benign in nature. Depending on the cultural context, acute neck pain can be associated with persistent complaints and disability, making the complaints even more frightening. Dysfunctional coping styles could lead to worsened pain experience or catastrophic interpretations of symptoms, thereby contributing to a bad prognosis. An active coping style is usually considered preferable, and improving active coping strategies is often advised as a main treatment goal.³⁵ Dysfunctional coping styles could lead to a heightened pain experience or catastrophic interpretations of symptoms, thereby contributing to a bad prognosis.

The use of passive coping styles is associated with prolonged symptoms.^36,³⁷ Previous research has shown that patients who believe they can control their pain, who avoid catastrophising about their condition and who believe they are not severely disabled appear to function better than those who do not. Such beliefs may mediate some of the relationships between pain severity and adjustment.³⁸ This finding suggests that there is a possible relationship with expectations and, hence, causal attribution. However, other research has found no evidence that coping styles influenced the outcome. This may be due to differences in the questionnaires used and, hence, in the definitions and participants.³⁹

Catastrophising and kinesiophobia

The fear-avoidance model was developed in relation to low back pain to provide an integrated model of the risk factors known to be associated with pain.^40,⁴¹ When acute pain is not perceived as threatening, patients usually continue daily activities, thereby promoting functional recovery. However, when pain is catastrophically misinterpreted, a vicious circle may be initiated in which catastrophising leads to pain-related fear, which leads to avoidance behaviour, including the avoidance of movement and physical activity, resulting in disuse and continuing pain. In support of the fear-avoidance model, studies on chronic pain conditions suggest that excessive pain catastrophising and fear of movement/(re)injury (kinesiophobia) are important in the aetiology of chronic symptoms.⁴² Pain catastrophising has consistently been associated with disability in patients experiencing pain.^43,⁴⁴ In avoidance behaviour, activities that are thought to increase or cause pain are avoided. Various studies demonstrate that patients with chronic low back pain avoid behavioural performance tasks.⁴⁰ In cases of low back pain, fear-avoidance beliefs are identified as risk factors for chronic low back pain, suggesting that these factors play a critical role.

Patients with chronic low back pain who retrospectively reported a sudden traumatic pain onset exhibited more kinesiophobia than patients who reported that the pain had started gradually.⁴⁵ In the case of whiplash, the onset of pain is often described as sudden, possibly setting the stage for the development of kinesiophobia, which in turn may contribute to a chronic course. Patients who are fearful of pain may focus on possible threats, thereby not only disrupting attentional processes, and thus leaving less attention available for other tasks but, also, experiencing intensified pain.^46,⁴⁷

Pain catastrophising refers to an exaggerated negative interpretation of actual or anticipated pain.⁴⁸ Earlier research has found that the habitual tendency to make catastrophic interpretations of pain is associated with a heightened pain experience in various patient groups.⁴⁹ Furthermore, catastrophising has been associated with heightened disability in chronic pain, independent of the level of actual physical impairment.⁵⁰^–⁵²

Because of the apparent role of kinesiophobia in the transition from acute to chronic low back pain, it may play a role in recovery from acute neck pain as well.⁵³ However, current research demonstrates ambiguous results. Some studies found kinesiophobia to be related to the development of chronic whiplash symptoms or disability.^54,⁵⁵ However, other studies showed no predictive value for kinesiophobia.^26,⁵⁶

One possible explanation for the possible limited role of kinesiophobia in whiplash could be that anxiety-related factors play a more prominent role than in low back pain. Because neck pain starts or is attributed to an often stressful MVC, this distinguishes it from most cases of low back pain and could give rise to more or different forms of anxiety. The sudden, traumatic onset could give rise to stronger somatic beliefs and related fears regarding recovery. Furthermore, it may be that neck pain in itself is experienced as more frightening than low back pain. All in all, the available research suggests that anxiety is associated with recovery from whiplash but that fear of pain or (re)injury specifically seems unrelated to the prognosis of post-traumatic neck pain.

Earlier work in the context of chronic disorders characterised by unexplained physical complaints, such as chronic low back pain, has provided evidence to suggest that pain catastrophising and attributional bias are of great importance in the development of chronic complaints.⁵⁷ It has been found that the habitual tendency to make catastrophic interpretations of pain is associated with a heightened pain experience in various patient groups.⁴⁹ Furthermore, catastrophising has been associated with greater disability in chronic pain, independent of the level of actual physical impairment.^50, ^{52, 58} It has been shown that, consistent with research into chronic pain, pain catastrophising is related to concurrent neck disability.^50,⁵² Catastrophising may lead to increased physical complaints, thereby indirectly contributing to a delayed recovery. Both catastrophising and fear of movement have been found to be predictors of disability and depression.⁵⁵ However, other research suggests that pain catastrophising is associated with neck disability but has no independent predictive value regarding recovery.⁵⁹ In summary, the fear-avoidance model and its components show some promise in helping to understand cases of whiplash-related neck pain.