Post-traumatic stress disorder and pain following motor vehicle collisions

What is post-traumatic stress disorder?

The theoretical explanations of post-traumatic stress disorder (PTSD) have become increasingly complex over the last two decades. Whereas initial descriptions of this disorder treated it as a traumatically induced fear condition,[1] more recent theories have integrated a wealth of data and view it as a condition maintained to a great extent by individual appraisals of danger, personal competence, and the trustworthiness of the world,[2] as well as negative emotional responses to resource loss.[3]

Post-traumatic stress disorder is a diagnosis given to distressed individuals who have been exposed to some event that threatens their life or physical well-being.[4] Symptoms include:

• Involuntary intrusive thoughts. 
• Images or dreams of the traumatic event. 
• Symptoms of physiological hyperarousal (e.g., concentration deficits, sleep disturbance, irritability). 
• Frequent attempts to avoid activities, thoughts, or emotions that remind the person of the traumatic event. 
• A state of decreased interests or emotional numbness.

To meet diagnostic criteria for PTSD, an individual must suffer from at least one re-experiencing, three avoidance/numbing, and two hyperarousal symptoms. Failure to meet the avoidance/numbing symptom criterion is the most common cause of distressed individuals failing to meet full criteria for PTSD. These symptoms must have lasted at least 1 month and cause significant distress and/or disability. Diagnostic errors most common among clinicians include:

• Failing to review patients’ exposure to traumatic events. 
• Relying on one favorite symptom (e.g., nightmares) as a so-called “cardinal” symptom of PTSD and thus not conducting a full symptomatic review. 
• Adhering to a confirmatory bias once a traumatic event (e.g., rape, MVC) has been identified without detailed symptomatic review. 
• Failing to review the extent of related work or social disability associated with symptoms.

The first error leads to substantial under-diagnosis of PTSD, while the latter three errors result in over-diagnosis of PTSD.

How common is PTSD following MVCs?

A well-designed epidemiological study found that civilian traumas (sexual and physical assault, MVCs) were the most common precipitants of PTSD with conditional prevalence of 12% and 11% respectively.[5] PTSD criteria were met at 3 months post-admission to physical trauma units following MVCs in 13% of consecutive admissions.[6] A further 17% were symptomatic but did not meet full diagnostic criteria. Thus, among MVC survivors sustaining some type of physical injury, the prevalence of PTSD is in excess of 10%, with a substantial number of sub-threshold cases that miss formal diagnostic criteria.

Remission of PTSD

It is important to understand the natural course of PTSD left untreated. While initial assessments of motor vehicle collision survivors suggest between 25% and 39% meet criteria for PTSD during the first 4 months post-collision, rapid remission is the rule. Thus, between one-half and two-thirds of original PTSD cases remit fully within 1 year. However, this leaves nearly 15% of original accident victims with PTSD 1 year following the collision.[7,8]

PTSD affects subjective health perceptions and health care use

PTSD symptom severity has been shown to be the mediating variable between traumatic life events and physical health problems in a sample of female Vietnam veterans.[9] Hyperarousal symptoms (e.g., hypervigilance, heightened startle response) were uniquely related to physical health concerns. Results from a sample of 1773 male Vietnam veterans showed that PTSD was related to greater use of general medical services, independent of other psychiatric disorders.[10] Primary care patients with PTSD were found to be overly frequent users of general medical care, with particularly high rates of complaints concerning musculoskeletal, digestive, neurologic, chest pain, gynecologic, ear, nose, throat, cardiovascular, and pulmonary symptoms.[11]

In a 5-year follow-up study of 1007 young adult patients of a health maintenance organization in the United States, individuals with a history of PTSD had higher levels of all somatization (physical complaint) symptoms in comparison to all other psychiatric disorders, as well as in comparison to non-distressed subjects.[12] An initial history of PTSD was associated with a later increased risk for chronic pain and other somatic conditions. Somatoform disorder patients are also much more likely to have histories of PTSD than of other anxiety disorders.[13]

Chronic pain occurs concurrently with PTSD

The severity of whiplash pain complaints in motor vehicle collision survivors is highly related to PTSD symptoms,[14] and post-traumatic headache patients have a very high incidence of PTSD.[15-17] Individuals with accident-related chronic pain conditions and high levels of PTSD symptoms report more severe pain and more depressive symptoms than chronic pain patients without PTSD.[18] In short, individuals with PTSD use much more in the way of general medical care, and traumatically induced pain patients are very likely to meet criteria for PTSD where PTSD appears to exacerbate pain complaints.

Physical pain exacerbates PTSD

Conceptually, physical pain can contribute to emotional conditions such as PTSD via two pathways. First, poorly controlled acute pain may serve as the traumatic event that fuels PTSD symptoms.[19] Theoretically, this explanation should be supported by evidence showing that objectively quantified severe physical injuries are more likely to produce PTSD. Unfortunately, the empirical evidence is mixed on this point. On one hand, the severity of injuries as assessed by the Abbreviated Injury Scale[20] has been shown to predict the onset of PTSD in motor vehicle collision survivors.[21,22] It was also noted that collision victims with PTSD symptoms had suffered more severe physical injuries.[23] However, other studies failed to find such a relationship between injury severity (measured in diverse ways) and PTSD symptoms.[24-28] The presence of fears of death at the time of the collision was as good a predictor of subsequent PTSD symptoms, as was injury severity.[25] Thus, the severity of the collision victim’s initial physical injuries is only a modest predictor of PTSD status.

Chronic pain as a trauma reminder or resource loss

Alternatively, chronic pain may serve as a reminder of the traumatic event. Physical pain symptoms may remind the individual of the traumatic event and thus contribute to a high state of emotional arousal. As well, chronic pain or slow recovery from a physical injury may serve as a highly salient reminder of resource loss and provide evidence to survivors that they have been permanently changed, or are incapable of controlling themselves or their environment.

Does chronic pain adversely affect PTSD? Possibly; the physical status of motor vehicle collision victims several months post-collision predicted the later development of PTSD.[29,30] Even physical health problems 5 years post-collision could predict the absence of PTSD remission.[31] In an open trial of cognitive behavioral therapy for MVC-PTSD, it was found that pain severity and disability were prominent predictors of response to treatment.[32]

Why does chronic pain have such a strong influence on PTSD? Perhaps an individual’s responses to traumatic stressors are influenced by their perceived resource loss.[3] These resources can be of many kinds, such as financial and social, but also include the resource of physical well-being. To the extent that individuals suffer permanent resource losses, they will be more distressed. It has also been learned that psychological distress is exacerbated by the trauma survivors’ perception that they have suffered a permanent change.[33,34] Coupled with the relentless course of aging and the known unreliability of retrospective memory for physical and emotional symptoms, individuals who suffer a very slow recovery from physical injuries incurred in a collision will often perceive a marked contrast between their physical well-being before and after the event, concluding that some permanent (pathological) loss in their physical well-being has occurred, and therefore remain psychologically distressed.

In short, physical well-being is an important resource to emotional well-being. When individuals suffer sudden losses in physical health, they become distressed. When an event is related to that decline in health, the average person tends to over-estimate pre-injury health and thus create a distressing comparison between pre-injury and post-injury health. If the individual perceives this as a permanent change, he or she will remain distressed. This distress often takes the form of PTSD.

Treatment of PTSD

To date, pharmaceutical treatments have had mixed success, with limited evidence of long-term benefits. Cognitive behavioral therapy, usually including a procedure called prolonged exposure, has received the most consistent support in research studies. Prolonged exposure is, as it sounds, a treatment that involves the client repeatedly reliving the memory of the traumatic event for lengthy periods of time (i.e., an hour or more) until his or her anxiety diminishes. Within cognitive behavioral therapy treatment protocols, prolonged exposure is often combined with graduated in vivo exposure exercises. For example, motor vehicle collision victims often suffer a residual fear of car travel. In vivo exposure exercises in this case involve driving (or riding as a passenger) repeatedly through feared situations such as unmarked intersections or highway on-ramps.

Forms of cognitive therapy are also often used in treating PTSD, including exercises to develop a more adaptive and realistic perception of threat or to re-evaluate the implications of trauma exposure to one’s future life. Most experts in the cognitive behavioral therapy treatment of PTSD believe that two changes are necessary for PTSD clients to show clinical improvement. The first is reduced avoidance behavior. Avoidance behavior may be overt (reduced driving in cars), or covert (avoidance of memories). The reliving exercise is meant to reduce covert avoidance and the in vivo exposure exercises are meant to reduce overt avoidance.

The second necessary change for successful treatment is to enable the client to change his or her appraisals of situations related to the collision. These appraisals may be about the trauma survivor him- or herself. For example, he or she may be permanently changed for the worse. Collision victims with physical injuries may view their entire lifestyle and self-image to have changed because of trauma-related change in physical functioning. Frequently, trauma victims come to believe that certain activities (such as car travel) are much more dangerous than previously assumed, and adopt excessively high levels of vigilance for specific types of threat. Finally, trauma victims are often disappointed in the safety net provided by society. They may come to believe that family, friends, employers, or insurance companies are non-supportive or adversarial. Such cognitive change is not always easy because a number of societal and social influences may reinforce trauma victims’ maladaptive beliefs (e.g., “There are so many bad drivers out there”).

Cognitive behavioral therapy treatments are effective for many PTSD sufferers in 15 or fewer hours of therapy. Despite our increasing knowledge of treatments that work, a number of PTSD sufferers do not improve with current treatments. For example, individuals who have chronic pain conditions resulting from the same trauma that precipitated their PTSD show less improvement. Individuals who are more severely depressed or who have high levels of anger about the trauma also do worse in treatment.[35]

Summary

PTSD is a common emotional disorder that can be linked to the physical and emotional trauma of motor vehicle collisions, as well as chronic physical pain disorders as they impact upon an individual’s control of his or her life and environment. If not recognized, PTSD can take on the characteristics of other emotional or physical maladies. Early recognition and conservative management through cognitive therapy and prolonged exposure therapy to the trauma memories can reduce the functional impact upon those victims.

Competing interests

Dr Koch has been given honoraria for speaking at CME meetings for the WCB and the Western Canadian Association of Disability Managers, has been paid as a consultant on ICBC and WCB claims, and has held research grants from ICBC.

William J. Koch, PhD

Dr Koch is a clinical professor in the Department of Psychiatry, University of British Columbia, and director of Psychology Residency Training at Vancouver Hospital and Health Sciences Centre.