Differences in Reactivity of Middle and Posterior Cerebral Artery in Patients with Neurocardiogenic Syncope

J Korean Neurol Assoc > Volume 26(1); 2008 > Article

Journal of the Korean Neurological Association 2008;26(1): 28-34.

신경심장성실신 환자들에서 중대뇌대동맥과 후대뇌동맥의 뇌혈관 반응 차이

박태환, 이은희a 윤영철a 김상욱b

서울의료원 신경과, 중앙대학교 의과대학 신경과학교실a, 심장내과b

Differences in Reactivity of Middle and Posterior Cerebral Artery in Patients with Neurocardiogenic Syncope

Tai Hwan Park

Department of Neurology, Seoul Medical Center; Department of Neurologya and Cardiologyb, Chungang University College of Medicine, Seoul, Korea

Abstract

Background: Neurocardiogenic syncope (NCS) is the most common type of neurally mediated syncopes. Though presyncopal symptoms may represent hypoperfusion in posterior circulation, studies for evaluating the cerebrovascular response of posterior circulation in patients with NCS were scanty. We evaluated the cerebrovascular response of the posterior circulation using transcranial Doppler monitoring in patients with NCS.
Methods: We measured the blood flow velocity (BFV) of the middle cerebral artery (MCA) and contralateral posterior cerebral artery (PCA) simultaneously in 11 patients with a diagnosis of NCS both at rest and during the head-up tilt test (HUT) for 5 minutes. The mean arterial pressure (MAP), pulse rate (PR), and end-tidal pCO2 (EtCO2) were also monitored. The obtained data were compared with those of 17 normal control subjects.
Results: The syncope patients showed a significantly larger decline in BFV of PCA (P<0.05) and a larger increase in pulsatility indexes of MCA and PCA during HUT compared to those of control subjects. In control subjects BFV of PCA decreased less than those of MCA. On the contrary, in patients with NCS, those of PCA decreased more. These different regional cerebrovascular responses to HUT were accompanied with neither presyncopal symptoms nor decrease in MBP.
Conclusions: The regional cerebrovascular response to HUT in NCS patients was different in the PCA flow. Impairment of autonomic neural control of posterior circulation may play an important role in the pathophysiology of NCS.KeyWords:Syncope, Transcranial Doppler, Posterior cerebral artery