Cerebral hemodynamics in obstructive sleep apnea.

We have investigated cerebral blood flow velocity (CBVF) in 14 patients with marked obstructive sleep apnea syndrome using transcranial Doppler ultrasonography during sleep. The CBFV increased during apnea, with a mean acceleration of 0.9 cm/s2, followed by a rapid decrease during snoring. The same effect was obtained by voluntary apnea in healthy subjects, showing a smaller acceleration rate (0.6 cm/s2). These results provide evidence for a normal CO2 regulation of cerebral vessels during sleep apnea and do not support the notion of cerebral hypoperfusion during sleep being a risk factor for stroke.