Posttraumatic Stress Disorder and Posttraumatic Stress Disorder-Like Symptoms and Mild Traumatic Brain Injury

Article excerpt

INTRODUCTION

The role of subtle persistent brain injury in the development and course of acute stress disorder (ASD) and posttraumatic stress disorder (PTSD) has been controversial, although many clinicians and medical authorities, as well as the public and media, assume that a relationship exists [1]. The military conflicts Operation Enduring Freedom (OEF) and Operation Iraqi Freedom (OIF) have brought to the forefront the issue of the relationship of concussion and blunt head trauma to combat stress reactions and combat-induced PTSD. As of June 25, 2007, over 26,000 U.S. service members have been wounded in action in OIF (www.defenselink.mil/news/casualty.pdf). Slightly more than half of combat injuries incurred early in OIF was from explosive blasts [2]. In addition to blasts, service members are at risk for head and bodily injuries due to projectiles (bullets, fragments), transportation accidents, and other environmental and combat hazards. Between January 2003 and February 2007, 29 percent of the patients evacuated from the combat theater to Walter Reed Army Medical Center in Washington, DC, had evidence of a traumatic brain injury (TBI). *

To estimate the frequency of concussion among combat troops who do not require medical treatment and evacuation is difficult. Many may be only briefly stunned or knocked unconscious by a blast or blow. However, even mild concussion, if recurrent, can cumulatively affect brain functions. Questions assessing TBI among all homecoming service members have been proposed to be included on the Post Deployment Health Assessment (a Department of Defense [DOD] form DD2796 to be completed when a service member returns from duty). Improved data collection at unit level and higher echelons of field medical care is currently being implemented.

In combat, experiences of fear, horror, and helplessness are ubiquitous. Does the occurrence of concussion increase the severity or likeliness of PTSD? Program evaluation data from U.S. marines surveyed following OIF indicate that combat troops reporting exposure to blasts had significantly higher levels of PTSD. In studies on the relationship between PTSD and injury of Vietnam veterans, findings showed two- to threefold higher rates of PTSD among this population than those who returned unharmed [3-4]. Furthermore, recent studies show that physical injury due to combat is a major risk factor for PTSD [5]. Thus PTSD is more likely among combat veterans who are injured. A review of the literature shows an increased rate of PTSD after TBI, with data from six studies yielding an estimated relative risk of 1.8 of those who developed PTSD over a maximum period of 7.5 years [6].

In this article, we review the current literature on PTSD and PTSD-like symptoms among individuals with mild TBI or concussion. We discuss four major areas. In the first area, we present general incidence studies of PTSD and effects of mild TBI on rates of PTSD symptoms, followed by a review of the literature on predictive factors and course of development of PTSD after TBI. We also present symptoms and symptom overlap between TBI and PTSD. Second, we review the neurobiology of PTSD and TBI. In the third area, we discuss the common psychiatric comorbidities associated with PTSD. In the fourth and final area, we focus on the general treatment and outcome of PTSD in the context of TBI.

CLINICAL ASPECTS

Traumatic Brain Injury

Mechanisms and Criteria

TBI may arise from physical damage by external blunt or penetrating trauma to the head, skull, dura, or brain or from acceleration-deceleration movement such as whiplash or coup-contrecoup, resulting in tearing or shearing of nerve fibers and bruising or contusion of the brain against opposite sides of the skull. Scraping of the brain across the rough bony base of the skull can cause contusion and can also affect the olfactory, oculomotor, optic, and acoustic nerves, leading to anosmia (total loss of the sense of smell, reduction of taste), double and/or blurred vision, and dizziness and/or vertigo. …