Chronic daily headache in U.S. soldiers after concussion.

OBJECTIVE To determine the prevalence and characteristics of, and factors associated with, chronic daily headache (CDH) in U.S. soldiers after a deployment-related concussion. METHODS A cross-sectional, questionnaire-based study was conducted with a cohort of 978 U.S. soldiers who screened positive for a deployment-related concussion upon returning from Iraq or Afghanistan. All soldiers underwent a clinical evaluation at the Madigan Traumatic Brain Injury Program that included a history, physical examination, 13-item self-administered headache questionnaire, and a battery of cognitive and psychological assessments. Soldiers with CDH, defined as headaches occurring on 15 or more days per month for the previous 3 months, were compared to soldiers with episodic headaches occurring less than 15 days per month. RESULTS One hundred ninety-six of 978 soldiers (20%) with a history of deployment-related concussion met criteria for CDH and 761 (78%) had episodic headache. Soldiers with CDH had a median of 27 headache days per month, and 46/196 (23%) reported headaches occurring every day. One hundred seven out of 196 (55%) soldiers with CDH had onset of headaches within 1 week of head trauma and thereby met the time criterion for posttraumatic headache (PTHA) compared to 253/761 (33%) soldiers with episodic headache. Ninety-seven out of 196 (49%) soldiers with CDH used abortive medications to treat headache on 15 or more days per month for the previous 3 months. One hundred thirty out of 196 (66%) soldiers with CDH had headaches meeting criteria for migraine compared to 49% of soldiers with episodic headache. The number of concussions, blast exposures, and concussions with loss of consciousness was not significantly different between soldiers with and without CDH. Cognitive performance was also similar for soldiers with and without CDH. Soldiers with CDH had significantly higher average scores on the posttraumatic stress disorder (PTSD) checklist compared to soldiers with episodic headaches. Forty-one percent of soldiers with CDH screened positive for PTSD compared to only 18% of soldiers with episodic headache. CONCLUSIONS The prevalence of CDH in returning U.S. soldiers after a deployment-related concussion is 20%, or 4- to 5-fold higher than that seen in the general U.S. population. CDH following a concussion usually resembles chronic migraine and is associated with onset of headaches within the first week after concussion. The mechanism and number of concussions are not specifically associated with CDH as compared to episodic headache. In contrast, PTSD symptoms are strongly associated with CDH, suggesting that traumatic stress may be an important mediator of headache chronification. These findings justify future studies examining strategies to prevent and treat CDH in military service members following a concussive injury.