Mild Traumatic Brain Injury and Pain in Operation Iraqi Freedom/ Operation Enduring Freedom Veterans

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INTRODUCTION

Pain is endorsed as one of the most frequent problems in veterans of Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) [1]. Gironda et al. studied OIF/OEF servicemembers registered for medical care at a southeastern Department of Veterans Affairs (VA) hospital and found that 42 percent of 533 patients reported a current problem with pain [2]. Over 50 percent of these patients endorsed pain levels in the clinically significant range (defined as a pain rating of greater than 4 on an intensity scale of 0-10). Similarly, in OIF/OEF veterans presenting for evaluation at a postdeployment health clinic, Helmer et al. found chronic widespread pain--defined in terms of the duration, distribution across the body, and perceived intensity of the pain--in 29 percent of the sample [3]. Further, the presence of chronic pain was associated with greater home and work-related disability. Back pain and headache were the most frequently reported pain symptoms in OIF/ OEF veterans [4].

While these studies highlight pain as an important postdeployment concern in the veteran population, it remains unclear what factors lead to such a high prevalence of pain in this population. One of the most obvious potential contributors to pain is a history of physical injury. Veterans are predisposed to overuse and traumatic orthopedic injuries by nature of their training and combat [5-6], and some of these injuries result in chronic musculoskeletal pain.

A second possible contributor to the relatively high prevalence of pain in returning veterans is mild traumatic brain injury (mTBI), the most common form of brain injury in veterans. Studies estimate that as many as 12 to 19 percent of OIF/OEF soldiers sustained deployment-related mTBI [7-8]. While most people completely recover in a matter of weeks to months following an mTBI [9-12], a small percentage of individuals report persistent postconcussive symptoms, including physical, cognitive, and emotional symptomology [13]. In addition to these commonly recognized persistent symptoms in a minority of individuals with a history of mTBI, pain is also quite commonly reported. The overall prevalence of chronic pain in the civilian TBI population is between 22 and 95 percent [14-15], with the prevalence of pain greater in the mTBI population than in those with more severe brain injuries. A meta-analysis of 10 studies with 1,046 individuals with a history of mTBI reported a pain prevalence rate of 75.3 percent (72.7%-77.9%); analysis of nine studies with 1,063 severe TBI patients reported a chronic pain prevalence rate of 32.1 percent (29.3%-34.9%) [16]. More than just another self-reported symptom, pain conditions can negatively affect recovery, vocational outcomes, and psychosocial functioning [3,17].

A third contributor to the pain experience is emotional functioning. The relationship between pain and psychological distress, particularly depression and anxiety, has been well documented (e.g., Sherbourne et al. [18]). Research suggests that psychological distress may increase pain and negatively affect a person's ability to manage and cope with pain [19]. Similarly, emotional distress has been shown to increase pain experience and has a profound effect on pain report with regards to frequency, intensity, and duration.

Pain has also been identified as a risk factor for developing mental health problems. The presence of chronic pain has been found to increase risk for developing psychological disorders, specifically depression [20]. Pain interference, as measured by functional limitations secondary to pain, has been linked to depression, and there is some evidence that pain interference is a stronger predictor of depression then actual pain severity [21]. Comorbid pain and psychological factors have also been linked to poor prognostic outcome [19].

Comorbid pain and posttraumatic stress disorder (PTSD) is a commonly reported problem in veterans. …