CHARLOTTE, N.C. – What may be the largest case-based study of patients with migraine and sleep-disordered breathing to date has found that, counter to prevailing thought, they may not be at higher risk of having obstructive sleep apnea (OSA) than nonmigraine patients, although further prospective studies are needed to validate that finding.
“This in no way for me changes the fact that, for patients that complain of headaches, sleep apnea remains to be something that should be considered as possible cause of their headaches,” neurologist and Cleveland Clinic postdoctoral fellow Eric Gruenthal, MD, said in an interview after he presented his results at the annual meeting of the Associated Professional Sleep Societies.
Dr. Eric Gruenthal
The study suggested that patients with migraine may have an OSA risk that “may be a little lower” than their nonmigraine counterparts, Dr. Gruenthal said. “But we have really yet to determine whether that’s true or not.”
Large case-based study
The retrospective case study included 4,783 migraine cases from the Cleveland Clinic electronic health record database who were case matched on a 1:3 basis with 14,287 controls. Patients with migraine had an average age of 47.5 years (±13.3) and body mass index of 33.7 kg/m2 (±8.6), and 76.4% were White. All patients had polysomnography (PSG) at a Cleveland Clinic facility from 1998 to 2021.
The analysis evaluated the collected data in two domains: sleep architecture, consisting of arousal index (AI), total sleep time (TST) and percentage of sleep stage time; and sleep-disordered breathing, including apnea hypopnea index (AHI) and mean oxygen saturation. The key findings of the migraine patients versus controls include:
- Lower AI, 19.6 (95% confidence interval, 12.8-30.9) versus 22.6 (95% CI, 14.7-34.9; P < .001).
- Shorter TST, 359 (95% CI, 307-421) versus 363 (95% CI, 306-432.5) minutes (P = .01).
- With regard to sleep stage, the percentage of N2 sleep was higher, 67.8% (95% CI, 59.6%-75.6%) versus 67% (95% CI, 58.4%-74.8%; P < .001); but the percentage of REM was lower at 16.7% (95% CI, 10%-22%) versus 17% (95% CI, 11.1%-22.2%; P = .012).
- Lower AHI, 7.4 (95% CI, 2.6-17) versus 9.5 (95% CI, 3.7-22.1, P < .001).
- Higher mean oxygen saturation, 93.7 (±2.4) versus 93.3% (±2.6; P < .001).
“Also,” Dr. Gruenthal added, “we found that the percentage of sleep time with oxygen saturation below 90% was lower among patients with migraine, at 1.3% versus 2.4%” (P < .001).
A unique profile?
The goal of the study was to determine whether migraine patients would have a unique PSG profile, Dr. Gruenthal said. “We were trying to overcome some of the limitations of previous studies, most notably those that use small sample sizes, and in some cases a lack of controls.”
The findings that migraine patients would have higher AI and elevated AHI ran counter to the study’s hypotheses, but fell in line with the expectation that they would have reduced TST, Dr. Gruenthal said.
Patients with migraine “may, in fact, exhibit a lower burden of sleep-disordered breathing, and that’s based on our findings such as the lower AHI and decreased burden of hypoxemia,” he said. “We theorized that this may be related to patients with migraine having a unique CGRP [calcitonin gene-related peptide] and serotonin physiology.” He noted that previously published research has shown that sleep CGRP and serotonin have a central role in causing arousal in response to rising CO2 levels during sleep, which can occur during apneas and hypopneas.
Dr. Gruenthal noted that the researchers are still analyzing the findings. “We theorized that possible indication bias may be present in our study,” he said. “It may be the case that patients with migraine are more likely to get their PSG done because of their headache and not for things like snoring and witnessed apneas, which may be more predictive of significant sleep apnea.” They’re also evaluating the “question of medicine confounding.”
Dr. Gruenthal added that “the big unanswered question out there is, if you have a patient with migraine who also has sleep apnea, by treating the sleep apnea will that improve their migraine?”