Chronic Daily Headache in U.S. Soldiers After Concussion

Brett J. Theeler, MD; Frederick G. Flynn, DO; Jay C. Erickson, MD, PhD

Disclosures

Headache. 2012;52(5):732-738. 

In This Article

Abstract and Introduction

Abstract

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.

Introduction

Over 160,000 U.S. military service members have been diagnosed with traumatic brain injury since 2000.[1] Concussions occur in 15–23% of U.S. service members deployed in support of Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF).[2–4] Headache is one of the most common symptoms after a concussion and may persist for months to years after injury. The prevalence of headaches in returning U.S. military service members who had a concussion while deployed to Iraq or Afghanistan ranges from 22% to 97%.[2,3,5]

Chronic daily headache (CDH), defined as 15 or more headache days per month, is one of the most disabling headache syndromes with a prevalence of 4–5% in the general population.[6,7] A number of primary headache disorders may manifest as CDH. Chronic migraine is one of the most common and most disabling forms of CDH among primary headache disorders. Secondary headache disorders can also manifest as CDH. Head trauma has been suggested as an important risk factor in the development of chronic daily headache in civilians. It has been estimated that 15% of cases of CDH in the general population are attributable to head or neck trauma.[8]

Little is known about CDH in military populations. Given the association between head trauma and CDH in civilians, we hypothesized that CDH would be highly prevalent among service members who had a concussion while serving in Iraq or Afghanistan. We previously reported the prevalence, characteristics, and impact of headaches in a large cohort of returning U.S. soldiers who had a concussion while deployed to Iraq or Afghanistan.[5] The aim of the current study was to determine the prevalence and characteristics of, and factors associated with, CDH in this same cohort of U.S. soldiers who had a deployment-related concussion.

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