1Department of Nerurology, Stroke Center, Kobe City Medical Center General Hospital, 2Department of Nerurosurgery, Stroke Center, Kobe City Medical Center General Hospital, 3Stroke Center, Osaka University Hospital
Severe carotid artery stenosis is a principle causes of ischemic stroke. For the patient with carotid stenosis, carotid endarterectomy (CEA) and carotid artery stenting (CAS) can prevent ischemic cerebrovascular diseases. In these carotid interventions, periprocedural neurological complications are caused primarily by (1) distal embolism, (2) decrease cerebral blood flow, and (3) hyperperfuion. Periprocedural transcranial Doppler (TCD) monitoring can detect changes in blood flow velocity and microemboli in real-time and, is useful for early detection and management of complications. In CEA, TCD detected microembolic signals (MES) during dissection and wound closure, >90% middle cerebral artery (MCA) velocity decrease during the period of cross-clamping, and >100% pulsatility index increase at clamp release, all of which have been associated with intraoperative stroke. In CAS using balloon protection devices, >90% MCA velocity decrease at balloon occlusion and MES after balloon protection release are related to development of neurological symptoms and new ischemic lesions. In CAS using filter protection devices, decrease in MCA velocity during protection suggests occurrence of no flow/slow flow phenomenon, both of which are associated with higher risk of distal embolic stroke. In both CEA and CAS, post-operative >100% increase in MCA velocity may be associated with development of hyperperfusion syndrome. TCD monitoring thus appears useful during and after carotid interventions when monitoring is deemed necessary.