[Relationship between sleep apnea and cerebral blood flow].

OBJECTIVE: To study the cerebral blood flow in patients with and without sleep apnea syndrome (SAS). METHOD: Thirty patients with SAS were studied, with 32 patients without SAS as controls. The age, sex and baseline diseases were comparable between these two groups. Subjects were studied by polysomnography and transcranial Doppler ultrasonography. The systolic (VS) and mean (VM) cerebral blood flow velocities, resistent index (RI), and frequency spectral shape were determined. Anterior, middle and posterior cerebral arteries were examined by transcranial Doppler ultrasonography in all patients. RESULT: VS and VM were significantly lower in patients with SAS than those in the control subjects (P < 0.05 and P < 0.01). RI of the right PCA in SAS patients (0.56 +/- 0.06) was significantly higher than that in the controls (0.48 +/- 0.09, P < 0.05). Changes in the cerebral blood flow frequency spectral shape were remarkably increased in the SAS group as compared to control group. VS and VM were negatively correlated with apnea index (r = -0.413 and -0.628, P < 0.05 and 0.01), but positively correlated with SaO2(r = 0.435 and 0.712, P < 0.05 and 0.01). CONCLUSION: The results suggest that SAS patients have decreased cerebral blood flow velocities and more frequency shape abnormalities. These may decrease cerebral perfusions, and lead to cerebral atherosclerosis and stroke.