Headaches and medical evacuation from the combat zone.

Over the last century the pattern of diseases and injuries among military combatants has shifted dramatically due, in large part, to advances in medical technology and disease prevention. Respiratory and infectious maladies were the top reasons for hospital admission during World Wars I and II, and the Korean War. During Operation Iraqi Freedom and Operation Enduring Freedom, musculoskeletal disorders and combat injuries have emerged as the leading causes of medical evacuation (1). Neurological disorders, including headache, rank third (1). Existing data indicate that the impact of headache disorders on the US military is substantial. Annually, 2.5% of males and 9.5% of females in the military will have a medical encounter for headache (2). An estimated 19% of US soldiers experience migraine headaches while deployed to a combat zone, impairing their ability to perform duties and contributing to sick call visits (3). Headaches are especially common among returning soldiers who have had a deployment-related concussion, with up to 97% reporting headaches and 37% having headaches that meet criteria for chronic post-traumatic headache (4). An observational study by Cohen et al. in this issue provides valuable new information about headaches as a cause of medical evacuation among US military personnel deployed to a combat zone. The medical records of 958 personnel who were medically evacuated for headaches from Operation Iraqi Freedom and Operation Enduring Freedom to Landstuhl Regional Medical Center in Germany between 2004 and 2009 were reviewed to determine the prevalence of various headache subtypes, demographics, treatment patterns, and return to duty rates. This is the first study specifically examining headache as a cause of medical evacuation from a war zone. A majority of study subjects were males (87%) and members of the Army (78%), with a mean age of 29.6 years. The most common headache disorders among military medical evacuees were post-concussive headache (34%) and migraine (30%). This is not surprising given the high prevalence of migraine and concussion in military personnel involved in combat operations in Iraq and Afghanistan. The results of the study confirm migraine and post-concussive headache as causes of unit attrition in the modern era of military conflict. The outcome of each study subject was based on their disposition from Germany, which usually occurred within 2 weeks of arrival. A positive outcome occurred if the individual returned to duty (RTD) in the combat zone. RTD is a meaningful outcome and the investigators should be commended for assessing it. Overall, 34% of those evacuated for headaches subsequently returned to duty. Nearly 40% of migraineurs returned to duty whereas only 19% of personnel with post-concussive headache returned. The authors identified multiple features associated with a lower likelihood of returning to duty to include continuous headache (as opposed to episodic), traumatic brain injury, physical trauma, and psychiatric comorbidity. The identification of prognostic factors in this study will help to inform decisions regarding medical evacuation of military service personnel with headache disorders. Moreover, the findings highlight the importance of both physical and emotional trauma as factors influencing the prognosis of headache in deployed military personnel. Notably, the study by Cohen et al. was conducted prior to the implementation of current US military policy which mandates immediate evaluation of all US military personnel exposed to potentially concussive events. Personnel with persistent symptoms after concussion and those with three or more concussions in a 12-month period are sent to higher centers of care within the combat zone for further evaluation and treatment by multidisciplinary teams that include neurologists, neuropsychologists, behavioral health specialists, and rehabilitative specialists. Early identification and