Spectral changes of near-infrared spectroscopy signals in migraineurs with aura reveal an impaired carbon dioxide-regulatory mechanism.

Subjects suffering from migraine with aura (MwA) present an altered cerebral autoregulation during migraine attacks. It is still unclear whether MwA sufferers present a normal autoregulation during attack-free periods. In this study, we characterized cerebral autoregulation in the frequency domain by analyzing the spontaneous oscillations superimposed on the cerebral hemodynamic signals, as detected by near-infrared spectroscopy (NIRS). Ten healthy women (age: 38.4 +/- 9.5 years) and ten women suffering from MwA (age: 35.2 +/- 10.5 years) underwent NIRS recording in resting conditions and during breath-holding (BH). Being the NIRS signals during BH nonstationary, we used the Choi-Williams time-frequency distribution to perform spectral analysis. We considered 256 s of signals and quantified the variation in the power of the very-low frequencies (VLF: 20-40 mHz) and of the low frequencies (LF: 40-140 mHz) as response to BH. Results showed that BH increases the power in the LF band both in healthy and MwA subjects. Considering the signal of the deoxygenated hemoglobin, the average power increase in the LF band was equal to 20% +/- 15.4% for the healthy group and significantly lower, 4.8% +/- 8.3%, in the MwA group (Student's t test, P < 0.02). No significant difference was observed in the VLF band or in the oxygenated hemoglobin signal power variations of the LF and VLF bands. The resulting data reveal a possible impairment in the carbon dioxide-regulatory mechanism in MwA subjects.