LOS ANGELES—Among US soldiers returning from deployment, 29% of those with mild traumatic brain injury (TBI) had migraine, and 12% of those without TBI had migraine, according to data presented at the 54th Annual Scientific Meeting of the American Headache Society. “This rate is considerably higher than you would generally find in a young male population,” said Ann I. Scher, PhD, Associate Professor of Epidemiology at Uniformed Services University in Bethesda, Maryland.
Among returning soldiers with migraine, 36% of those with TBI reported visual auralike symptoms, compared with 20% of those without TBI. Dr. Scher and her colleagues considered many of the auras typical, because they had a gradual onset and lasted for the appropriate amount of time (ie, 5 to 60 minutes). Most soldiers’ auras were atypical, however, either because they did not meet these criteria or soldiers were not certain whether they did.
An Ongoing Study of Soldiers With and Without TBI
These epidemiologic data are preliminary results from an ongoing study that Dr. Scher and her colleagues are conducting. The researchers plan to recruit 1,500 soldiers returning from deployment, including 750 who screen positive for mild TBI and 750 who screen negative. To screen positive for TBI, a soldier must report a relevant injury that resulted in an alteration of consciousness, such as momentary confusion. Soldiers will be enrolled at Fort Bragg and Fort Carson.
Dr. Scher presented data for 174 soldiers with mild TBI and 202 controls, all enrolled at Fort Carson. “None of these soldiers was medically evacuated, so these are all mild injuries,” she said. Headaches were assessed with a self-administered questionnaire adapted from one developed by Richard Lipton, MD, Professor of Neurology at Albert Einstein College of Medicine in the Bronx, New York, and Walter F. Stewart, PhD, Associate Professor of Epidemiology at Johns Hopkins University in Baltimore. Participants also completed the Chronic Pain Grade questionnaire developed by Michael von Korff, ScD, Senior Investigator at Group Health Research Institute in Seattle. The investigators are conducting three-month, six-month, and one-year follow-ups.
TBI Is Linked to Probable Migraine and Chronic Daily Headache
To date, 94% of participants with TBI were men. Men accounted for 98% of soldiers who screened negative for TBI. Approximately 69% of soldiers with TBI were Caucasian, compared with 62% of soldiers without TBI. About 8% of soldiers with TBI were African American, compared with 13% of soldiers without TBI. Slightly more soldiers reporting TBI were in combat-related occupational categories (57%), compared with soldiers without TBI (50%). Head injuries among soldiers in both combat and combat support roles sometimes were due to motor vehicle accidents and falls, said Dr. Scher.
In addition to soldiers meeting all criteria for migraine, 24% of soldiers with TBI had probable migraine, compared with 20% of returning soldiers without TBI. About 9% of returning soldiers with TBI had not had a headache in the previous year, compared with 21% of returning soldiers without TBI.
Approximately 22% of soldiers with TBI had chronic daily headache, including 9% with a continuous chronic daily headache. About 7% of returning soldiers without TBI had chronic daily headache. One of these soldiers had a continuous headache, and the rest had episodic very frequent headache or headache-free periods. Chronic daily headache was “considerably more common” than might be expected, said Dr. Scher. “Based on civilian populations, it should have been prevalent in 1 to 2% of men.”
Assessing Chronic Pain in Soldiers
In the chronic pain assessment, which used slightly different questions, headache and migraine, the most common symptoms, were reported by 71% of soldiers with TBI and 51% of soldiers without TBI. Back pain, however, was considered the most bothersome symptom by 34% of all soldiers, regardless of TBI history. Nearly 25% of all soldiers reported joint pain, and 6% reported neck pain. The heavy equipment that soldiers carry could explain these symptoms, according to Dr. Scher. The pain “is presumably transient, and we’ll have follow-up interviews, but for now, we can see at baseline that there’s really a lot of pain in general in this cohort,” she added.
Implications for the Treatment of Post-Traumatic Headache
The diagnostic criteria for post-traumatic headache, which are being revised, should perhaps be modified to reflect these and other data, said Dr. Scher. According to the criteria, post-traumatic headache has “no typical characteristics,” but the data suggest that post-traumatic headache often takes the form of migraine or chronic daily headache.
The criteria also require headache to occur within seven days of injury or of regaining consciousness after injury. “The seven-day rule is not optimal,” Dr. Scher told Neurology Reviews. “I don’t think we know what the number should be. Hopefully, in the future we’ll have a more empirical case definition—one that we can justify with data.
“When we finish our study and some of the other ongoing studies, we’ll have a much better idea of what the post-traumatic headache phenotype is,” added Dr. Scher. “Once we have a better feeling for what the phenotype is, we can start talking about focused clinical trials in this population.”
In addition to her ongoing study, Dr. Scher plans to examine whether continuous headache and auralike symptoms could be useful diagnostic markers for combat-related post-traumatic headaches.
Stewart WF, Lipton RB, Dowson AJ, Sawyer J. Development and testing of the Migraine Disability Assessment (MIDAS) Questionnaire to assess headache-related disability. Neurology. 2001;56(6 Suppl 1):S20-S28.
Von Korff M, Ormel J, Keefe FJ, Dworkin SF. Grading the severity of chronic pain. Pain. 1992;50(2):133-149.