Abstract TMP80: Intraoperative Blood Flow Changes Predict Angiographic Outcomes After Direct Cerebral Revascularization For Moyamoya Disease

Introduction: Moyamoya Disease (MMD) is a progressive steno-occlusive vasculopathy of the large intracranial vessels precipitating ischemic and hemorrhagic events. Cerebral revascularization is the mainstay of treatment in MMD. Intraoperative measurements of cerebral blood flow following direct intracranial bypass may be performed to quantitatively assess the anastomosis. Objectives: To correlate intraoperative flow parameters in direct cerebral bypass for moyamoya disease to postoperative angiographic and clinical outcomes. Methods: Consecutive patients undergoing direct superficial temporal artery (STA) to middle cerebral artery (MCA) bypass were retrospectively analyzed. Preoperative and 6-month postoperative patient data was collected including presenting symptoms, MRI and angiographic findings, neurological complications, and functional outcome. Intraoperative cerebral blood flow was measured from the donor and recipient arteries using a micro flow probe pre- and post-anastomosis. Results: A total of 50 direct revascularization procedures in 39 patients were analyzed, of which 40 were in females (80%). The mean flow prior to anastomosis in the M4 MCA was +2.2 ± 6.1 ml/minute and +26.8 ± 19.0 ml/min in the STA. Post-anastomosis, the mean flow was -10.9 ± 14.8 ml/min (towards the Sylvian Fissure) in the proximal M4 and +7.9 ± 9.2 ml/min in the distal M4. At 6-month follow-up angiography, the graft was patent in all cases, with 98% demonstrating direct supply. A component of indirect supply was observed in 56% of grafts. Matsushima grade A, B, and C revascularization were obtained in 64%, 20%, and 16% of cases, respectively. Amongst Matsushima grade A patients, low flow was observed in the M4 (mean 1.7 ± 4.8 ml/min) prior to bypass, which became retrograde following bypass, measuring -13.5 ± 16.0 ml/min. Lower post bypass flow was observed in grade B and C patients, with -6.8 ± 13.1 ml/min and -5.6 ± 10.3 ml/min, respectively. Postoperative stroke occurred in one patient, who had a Matsushima grade C. Conclusions: Greater intraoperative retrograde flow in the recipient MCA immediately following anastomosis was observed in patients achieving a higher Matsushima grade.