ARTICLE IN BRIEF
After excluding people who reported headaches prior to 9/11, investigators reported that 43 percent of the remaining 765 people reported frequent headaches in the four weeks preceding study enrollment and 54.6 percent reported exposure to the initial WTC dust cloud, which was found to be a risk factor for developing headaches.
Nearly nine years after the 9/11 attack on the World Trade Centers (WTC), the health effects on local residents and workers exposed to the attack and its aftermath are still being felt. Several conditions, listed on the WTC Medical Monitoring and Treatment Program Web site, www.wtcexams.org, have been linked to WTC exposure or injury, including aerodigestive disorders, mental health conditions, and musculoskeletal disorders
Not on this list are headaches. Although surveys show that headaches were a common symptom in people living and working in the WTC area on and after 9/11, according to investigators at the Bellevue WTC Environmental Health Center, no data exist on whether headaches have persisted over time for these people.
“We became interested in studying this population when we saw a higher than expected incidence of headache in our World Trade Center clinic population,” said Katherine Henry, MD, associate professor of neurology at the New York University (NYU) School of Medicine and Bellevue Hospital Center, one of the study authors.
The investigators at the Bellevue's WTC Environmental Health Center hypothesized that, like respiratory symptoms, persistent headaches would be found and may be linked to prolonged exposure to the dust and fumes during and after the towers' collapse.
RESULTS OF ANALYSIS
The study included 803 consecutive patients enrolled in the Bellevue Hospital WTC Environmental Health Center between December 2005 and March 2009 who were asked to document their exposure to WTC dust and fumes and new onset headaches and other physical symptoms.
After excluding people who reported headaches prior to 9/11, the investigators reported that 43 percent of the remaining 765 people reported frequent headaches in the four weeks preceding study enrollment and 54.6 percent reported exposure to the initial WTC dust cloud, which was found to be a risk factor for developing headaches. In addition, the people who reported headaches also were more likely to report wheezing, dyspnea with exercise, nasal drip and sinus congestion, and gastroesophageal reflux disease.
According to lead author Sara Crystal, MD, an instructor of neurology at NYU School of Medicine, who will present the study at the upcoming AAN annual meeting in Toronto next month, these findings support the hypothesis that headaches are a predominant and persistent symptom in people exposed to the WTC dust and fumes. What remains unknown from their study, however, is the exact association between the exposure to the dust and fumes and persistent symptom of headaches.
Commenting on the study, Stephen Silberstein, MD, professor of neurology at Jefferson Medical College of Thomas Jefferson University in Philadelphia, said teasing out the reason behind the headaches is difficult. “I don't doubt the persistent headaches found in the study,” he said, “but I think they are more related to post-traumatic stress.”
Dr. Silberstein, who was not involved with the study, noted that other studies had shown that headaches are common in military personnel returning from combat. He noted that it was difficult to separate out exposure to fumes and exposure to stress. “The problem is that the two coexist,” said Dr. Silberstein.
Dr. Crystal said that the study did not explore the relationship between mental health symptoms and headache. But she said there is a need for further studies to “better understand the interplay between headaches, other physical symptoms, and mental health complaints.” Studies are presently under way by the investigators to further explore this relationship.
Drs. Crystal and Henry agreed that correctly identifying the mechanisms underlying headaches and the suggestive role played by environmental factors is important to help guide treatment for people in whom headaches can have a huge impact on their daily functioning. “Disasters may play a larger role than previously thought in triggering primary headache disorders,” said Dr. Crystal.
Until a link can be established between the development of persistent headaches and exposure to the dust and fumes from the WTC attacks, patients who have had persistent headaches associated with fumes may best be helped by treating their headache disorder, trigger management, and addressing the psychological sequelae of 9/11, according to the investigators.
The study was conducted as part of a larger NIH-funded study at Bellevue's WTC Environmental Health Center, along with Joan Reibman, MD, a pulmonolgist and director of the Center, and her team of researchers.
Environmental Factors As Headache Triggers
Data from previously published studies that show an association between environmental factors and headaches have focused primarily on the role of the environment as a trigger to developing a headache. Among these data are studies that show an association between exposure to air pollution and headaches.
A 2009 paper in the American Journal of Epidemiology looked at the association between air pollution and daily numbers of hospitalizations for headache in seven communities in Chile between 2001 and 2005. The study authors reported that the number of headaches severe enough to warrant hospitalization was increased on days of greater air pollution. Ozone was found to be the pollutant most consistently associated with individual air pollutants. Other specific pollutants included carbon monoxide, nitrogen dioxide, sulfur dioxide, and particulate matter.
Although the study could not prove a causal relationship between air pollution and headaches, the authors suggested a plausible causal relationship based on biology. “Nociceptive stimuli may trigger headache, and neural and vascular changes are thought to be important in the pathophysiology of headache,” they wrote. “Sulfur dioxide and ozone are irritants, and air pollution influences neural and vascular activity.”
Similar findings were reported in a 2009 paper in the International Journal of Occupational Medicine and Environmental Health that examined the association between air pollution and emergency department (ED) visits for migraine headaches in five cities in Canada. The investigators reported that the highest ED visits for migraines for women was on warm days with increased sulphur dioxide in the air, and for men on warm days with increased nitrogen dioxide in the air.
Further evidence on the role the environment plays in triggering headaches comes from military studies. A 2009 paper in Headache reported that environmental factors were the most commonly reported trigger for headaches in both 150 active-duty service members as well as 22 military dependents (or civilians) participating in the study. Of the total cohort of 172 patients, 128 (74 percent) reported environmental factors as the most common trigger. Environmental factors included noise, light/sun, heat, cold, fumes, odor, smoke, and vibration.
“Fumes, odors, and smoke were reported as triggers in our study population,” said Brett J. Theeler, MD, a neurologist at the Madigan Army Medical Center in Tacoma, WA, who led that study. “Our study supports the notion that environmental factors are important headache triggers in the military population including deployed U.S. soldiers.”
The study also found that stress was the second most common trigger reported in patients (60 percent), and was significantly more common in active duty soldiers than in the civilian military personnel.
Although the study did not assess the association between stress and environmental factors in triggering headaches, the study showed that headache triggers in a civilian population – including environmental- and stress-related triggers – are the same headache triggers that are the most common in a military population.