The linear behavior of the system middle cerebral artery flow velocity and blood pressure in patients with migraine: lack of autonomic control?

BACKGROUND AND PURPOSE Migraine is considered a disorder of the autonomic nervous system. We used the frequency analysis of dynamic cerebral autoregulation to assess whether blood flow regulation disturbances can be found at the frequencies at which sympathetic and parasympathetic activity is present. METHODS We measured simultaneously mean arterial blood pressure (BP) and the mean blood velocity (V) in the middle cerebral artery using transcranial Doppler ultrasound in 33 healthy controls (mean age+/-SD; 36+/-13 years) and in 22 patients with migraine (mean age; 39+/-7 years). Apart from assessing spectral power density for BP and V, we calculated the transfer function parameters gain, phase, and coherence at the frequency range between 0.0 and 0.25 Hz. RESULTS Compared with the controls, the spectral power density of BP and V exhibited a maximum magnitude of 10(26) in the migraine patients, whereas the maximum magnitude of BP and V in the controls was 10(-3). Coherence showed no difference between patients and controls. Gain between BP and V increased in the controls >0.01 Hz but was approximately 0 or negative in the migraine patients over the whole frequency range (P<0.01). The usually observed phase lead of V against BP was absent in the migraine patients in whom BP leaded V over nearly the whole frequency range (P<0.01). CONCLUSIONS In terms of phase and gain, dynamic cerebral autoregulation is completely different in migraine patients compared with healthy subjects. Insofar, this can be interpreted as a lack of sympathetic and parasympathetic control of cerebral blood flow.