Evaluation of Cerebrovascular Reactivity and Reserve Capacity in Patients with Middle Cerebral Artery Stenosis
QI Feng, XU En, LU Xuefen, Chen Xiumei Institute of Neuroscience, the Second Affiliated Hospital of Guangzhou Medical C ollege, Guangzhou 510260, China
Objective: To investigate the cerebrovascular reactivity and reserve capacity in patients with middle cerebra l artery(MCA)stenosis. Methods: Seven ty-five ischemic stroke patients with MCAs stenosis were enrolled in this study . All the patients were routinely examined with transcranial Doppler (TCD), and then TCD 8.0 software was used to evaluate the cerebrovascular reactivity and re serve capacity. Hypercapnia was induced by inhaling the 5% CO 2 and 95% O 2 mixed gas from modified anesthesia air sac, and hypocapnia was induced by volunt ary hyperventilation. The changes of velocities were recorded in both sides of M CA. Results: Routine examination: 75 pa tients with 105 MCA stenoses, 44( 41.9% )of the MCA stenoses were mild grad e, 36(34.3%)of them were moderate and 25( 23.8% )of them were severe. Af ter 5% CO 2 inhalation and voluntary hyperventilation, the percentage of veloc ities in the both experiment groups was significantly lower than that of the two control groups ( P 0.01). With the aggravatio n of MCA stenosis, the changing rate of velocity gradually decreased. Conclusion: Because MCA stenosis, bloodstream is blocked in patients with MCA stenosis in ischemic stroke, both cerebrovascular r eactivity and reserve capacity decrease; the severer the stenostic grade, the lo wer the declination of cerebrovascular reactivity and reserve capacity, and the higher the risk of low perfusion stroke.