Indirect revascularization for nonmoyamoya intracranial arterial stenoses: clinical and angiographic outcomes

Abstract

Object: Symptomatic intracranial arterial stenoses have a high rate of recurrent stroke despite medical and endovascular treatments. The authors present clinical and angiographic quantitative outcomes of indirect revascularization for patients with symptomatic intracranial stenosis.

Methods: Patients treated for symptomatic intracranial arterial stenosis by indirect revascularization were included. The patient population comprised those in whom medical management had failed and for whom endovascular therapy was unsuitable or had failed. Patients underwent encephaloduroarteriosynangiosis (EDAS) with or without bur holes. Preoperative and postoperative angiograms were evaluated for change in caliber of extracranial blood vessels (superficial temporal artery [STA] and middle meningeal artery [MMA]) and for evidence of neovascularization.

Results: Thirteen patients underwent EDAS. Ischemic symptoms ceased within the follow-up period in all patients, returning in a delayed fashion in only 2. No other patients had recurrent TIAs or strokes after the initial postoperative period. Donor blood vessels increased in size relative to preoperative sizes in all but 1 case (average increase of 52% for proximal STA [p=0.01], 74% for midpoint of STA [p=0.01], and 84% for the MMA [p=0.02]). In addition, 8 of 11 patients demonstrated direct spontaneous anastomoses from extracranial to middle cerebral artery branches, and all patients demonstrated angiographic evidence of vascular blush and/or new branches from the STA and/or MMA.

Conclusions: Indirect revascularization appears to be a safe and effective method to improve blood flow to ischemic brain due to intracranial arterial stenosis. Neovascularization and enlargement of the branches of the ECA were observed in all patients and correlated with improvement in ischemic symptoms. Indirect revascularization is an option for patients in whom medical therapy has failed and who are not suitable for endovascular treatment.

Figures

Fig. 1

Illustration showing the EDAS revascularization. The donor artery is placed close to the superficial brain arteries. A network of collaterals forms between the donor artery and the adjacent brain vessels without a surgical anastomosis.

Fig. 2

Case 13. Angiograms obtained in a 61-year-old woman with a history of hypertension, diabetes, and hypercholesterolemia who presented with recurrent TIAs and stroke and a near complete occlusion of the distal left internal carotid artery. She had previously undergone endovascular stenting that rapidly restenosed. A: The measurements of the STA and MMA were normalized to a fixed landmark, the anteroposterior extent of the sella turcica, to account for differences in magnification and allow comparison of pre- and postoperative angiograms. B and C: Angiographic demonstration of increased vessel size after indirect revascularization. Preoperative (B) and postoperative (C) selective ECA injections demonstrating an increase in size of the STA (white arrows) and MMA (black arrows). Direct filling of cortical MCA branches can be seen.

Fig. 3

Graphs demonstrating the change in the corrected measurements for the STA proximally (A), at its midpoint (B), and for the MMA (C) pre- and post-EDAS. The asterisks indicate the patient whose vessels decreased in size after surgery, the values on the y axis represent the size ratio (STA/sella turcica or MMA/sella turcica).

Fig. 4

Angiograms of spontaneous direct anastomoses from branches of the ECA to intracranial vessels in 6 patients. In each example, the cortical branches of the MCA fill directly from a selective ECA injection. CCA = common carotid artery.