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Updated: Aug 11, 2026
Functional Transcranial Doppler Ultrasound for Monitoring Cerebral Blood Flow
Published on: March 15, 2021
Hemodynamic flow patterns evaluated by transcranial color-coded duplex sonography after STA-MCA bypass for internal
Atsushi Umemura1, Kazuo Yamada, Atsuo Masago
1Department of Neurosurgery, Nagoya City University Medical School, Nagoya, Japan. aume@med.nagoya-cu.ac.jp
Insights
Superficial temporal artery-middle cerebral artery bypass surgery aids intracranial circulation. Preoperative collateral absence and poor cerebral perfusion predict successful bypass flow, assessed noninvasively by transcranial color-coded duplex sonography.
Area of Science:
- Neurosurgery
- Vascular Neurology
- Medical Imaging
Background:
- Extracranial-intracranial (EC-IC) bypass, specifically superficial temporal artery-middle cerebral artery (STA-MCA) bypass, is used for internal carotid artery occlusion.
- Predicting the contribution of bypass flow to intracranial circulation remains challenging.
Purpose of the Study:
- To examine intracranial hemodynamics after STA-MCA bypass.
- To correlate postoperative bypass flow contribution with preoperative collateral circulation and cerebrovascular perfusion status.
Main Methods:
- Retrospective study of 10 patients undergoing STA-MCA bypass.
- Intracranial hemodynamics assessed using transcranial color-coded duplex sonography (TCCD).
- Classification of MCA hemodynamics into three patterns based on bypass flow dependency.
Main Results:
- Three hemodynamic patterns identified: complete MCA perfusion dependency on bypass (A), M2 segment dependency (B), and inefficient bypass with collateral supply (C).
- Absence of anterior communicating artery collateral flow and Type 3 cerebral perfusion (reduced cerebral blood flow and vasoreactivity) predicted successful bypass hemodynamics.
Conclusions:
- TCCD is an effective, noninvasive tool for evaluating intracranial circulation post-EC-IC bypass.
- Preoperative assessment of collateral status and perfusion is crucial for predicting bypass efficacy.
Abstract:
Extracranial-intracranial (EC-IC) bypass surgery had been widely performed for the treatment of internal carotid artery occlusion. However, it is presently difficult to predict how the bypass flow will contribute to intracranial circulation. We examined intracranial hemodynamics by transcranial color-coded duplex sonography (TCCD) after superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and retrospectively studied the relationship between the postoperative contribution of the bypass flow and the preoperative collateral circulation and cerebrovascular perfusion status in 10 patients. Hemodynamics in the MCA detected by TCCD were classified into three patterns. In pattern A, perfusion of the whole MCA area is completely dependent on the bypass flow. In pattern B, perfusion of the M2 segment is dependent on the bypass flow, but perfusion of the M1 segment is independent of the bypass flow. In pattern C, perfusion of the whole MCA area is supplied by collateral flow and the bypass does not function efficiently. Preoperative absence of collateral flow via anterior communicating artery and cerebral perfusion status type 3 (reduced regional cerebral blood flow and regional cerebral vasoreactivity) seems to predict hemodynamic usefulness of the bypass flow after surgery. TCCD is an easy and noninvasive method for evaluating intracranial cerebral circulation after EC-IC bypass surgery.
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