Sequential Extradural Release of the V3 Vertebral Artery to Facilitate Intradural V4 Vertebral Artery Reanastomosis: Feasibility of a Novel Revascularization Technique

BACKGROUND: Revascularization of the intradural vertebral artery (VA) usually involves V3-V4 bypass using an interposition graft. The interposition of a graft increases surgical time, adds risks, and requires 2 suture lines. OBJECTIVE: To assess the feasibility of an excision-reanastomosis of V4 by sequentially releasing V3. METHODS: Twenty specimens were prepared for surgical simulation of a far-lateral approach. The third and fourth segments of the VA were exposed through the far-lateral approach bilaterally. The V3 segment was divided into three subsegments: (1) V3(f): from entry to C1 transverse foramen to the point of exit from C1 transverse foramen; (2) V3(s): from V3(f) to the distal point of V3 within the sulcus arteriosus; and (3) V3(d): from point V3 leaves the sulcus arteriosus to its dural entrance. After transecting the VA 2 mm proximal to the posterior inferior cerebellar artery origin, each subsegment was released sequentially. We measured the lengths obtained before and after releasing each segment by pulling the VA along its main axis to recreate a V3-V4 excision-reanastomosis. RESULTS: The V3 could not be weffectively mobilized without release. When totally released, an average length of 13.15 mm was available for completing V3-V4 reanastomosis. CONCLUSION: Complete release of V3 from all its adhesions in its extracranial course can provide an average length of 13.15mm for excision-reanastomosis. The present study shows the anatomic feasibility of the use of V3 segment in primary anastomosis after excision of a diseased segment of the intradural VA, laying the basis for future clinical application.