PHILADELPHIA — Migraineurs—especially those with aura—have a significantly increased risk of developing deep matter white lesions and subclinical brain infarcts in the posterior circulation than do control subjects.
The findings of CAMERA II, a 9-year follow-up study, confirm those seen in the original Cerebral Abnormalities in Migraine, an Epidemiological Risk Analysis (CAMERA I): Patients with migraine are more likely to have subclinical brain lesions than were those without migraine.
CAMERA II wrapped up just days before the annual meeting of the International Headache Society, where Dr. Michel Ferrari presented the unadjusted data and said that a more refined analysis would be forthcoming.
CAMERA I included 140 controls, 164 migraine patients who experienced aura, and 134 migraine patients without aura who underwent magnetic resonance imaging, and clinical and cognitive testing. Although there were no significant overall differences in the prevalence of infarcts between controls and patients, patients with migraine and aura had a significantly higher prevalence of infarcts in the posterior circulation than controls (5% vs. 0.7%)—an adjusted odds ratio of 14. The highest risk was seen in patients with migraine and aura who experienced one attack or more per month (OR 16).
Women with migraine also had a significantly increased risk of a high volume of deep matter white lesions (OR 2). The risk increased with increasing attack frequency, being highest in those with more than one attack per month (OR 3).
“The most interesting finding in CAMERA I was this recurrent theme of higher risk with having had more migraine attacks,” said Dr. Ferrari, chairman of the Leiden (the Netherlands) Center for Translational Neuroscience at Leiden University. “That suggested to us that there must be progression, so we decided to do this follow-up study.
CAMERA II included 66% of the CAMERA I cohort (83 controls and 203 patients with migraine). Subjects underwent another MRI, cognitive testing, transcranial Doppler imaging for right-left shunting, and cerebellar test battery. The investigators used equipment and protocols similar to those used in CAMERA I.
In a comparison of volume of deep white matter lesions, patients with migraines had greater increases than controls from CAMERA I to CAMERA II. The difference was significant in patients with migraine and aura: In CAMERA I, the mean volume was 0.19 mL, increasing to 1.28 mL in CAMERA II.
There was also a significant increase between the studies in the percentage of migraineurs with infarcts. In CAMERA I, 9% of patients with migraine had any infarct, compared with 15% in CAMERA II. Posterior circulation infarcts increased as well, from 5% in CAMERA I patients to 9% in CAMERA II. “Among the 11 migraineurs in CAMERA I who had a posterior circulation infarct, 3 had had a new one by CAMERA II,” Dr. Ferrari said. “CAMERA II also showed seven incident posterior circulation infarcts in migraineurs, although there were no incident infarcts among the controls.”
The findings must be carefully considered, he said, since there were some significant baseline differences between those who developed infarcts and those who did not. Those with infarcts were older (62 vs. 57 years), more likely to be taking statins (39% vs. 17%) and antihypertensives (61% vs. 27%), and more likely to have hypertension (94% vs. 58%).
Without controlling for those factors, he said during the question-and-answer period, it's not possible to tell whether the migraines caused the infarcts, or whether they are more likely to be related to an unfavorable cardiovascular risk profile.