Flow Assisted Neurosurgery, Case # 102, Video Text
Courtesy F.T. Charbel, MD, Associate Professor, Dept. of Neurosurgery, University of IL at Chicago
Case Summary
A patient with cerebrovascular occlusive disease received a bypass from the superficial temporary
artery (STA) to a cortical branch of the middle cerebral artery (MCA). The micro flowprobe was used to assess the patency and adequacy of the bypass. Key measurements in
an EC-IC arterial bypass are the free flow in the artery and the post-anastomotic flow in the bypass. The free flow measurements represent the maximum capacity of the
bypasss, since resistance to flow is zero and are the surgeon's benchmark for an optimally functioning bypass. After constructing the bypass, flow is measured again in the
donor artery. Bypass flow equal to free flow shows that the bypass is technically flawless.
Step 11. Surgical field before making skin incision. The solid black line marked on the skin shows the course of the STA. The dotted line shows a branch of the STA that will be swung over to connect to the MCA cortical branch. The STA is harvested in a pedicle.
Step 12. Flow is measured in the in situ STA, while it is still attached in the scalp and
resistance to flow is relatively high. In situ flow was 15 ml/min.
Step 13. Pre-craniotomy; the STA is wrapped. Post-craniotomy, the length of the STA is
measured. The dura is incised. The diameter of the STA pedicle is measured (4 mm).
Step 14. Flow is measured in the MCA recipient vessel before doing the bypass.
Step 15. Clips are placed on the proximal and distal STA and the artery is divided. The
proximal clip is removed and the STA free flow is measured. This measurement is important because there is zero resistance to flow and this gives the surgeon a
benchmark for the maximum flow carrying capacity of the STA. Free flow was 68 ml/min. Note that ultrasonic gel is used for acoustic coupling during the free flow
measurements.
Step 16. The distal end of the STA is skeletonized. The MCA is uncovered and the STA is brought alongside it and divided.
Step 17. The MCA is temporary clipped and the anastomosis is performed. A small shunt is
inserted into the MCA to prevent a stitch from catching the back wall. The shunt is removed before completing the anastomosis.
Step 18. The clip is removed to assess back bleeding through the anastomosis. The anastomosis is completed.
Step 19. STA bypass flow is measured. Shown first while still under the microscope; then followed by a wide shot, off scope. The STA bypass flow was 75 ml/min, confirming that it's a flawless bypass. Flow in the bypass is a little higher than the free flow because of the reperfusion hyperemia in the brain.
Step 20.
Flow is measured in the MCA recipient vessel after bypass. This measurement demonstrates the improvement in flow to the MCA territory.
