M2 plane rotation technique for approaching M2 perpendicularly to obliterate aneurysms with interlocking clipping: Technical case report

•The interlocking tandem clipping technique can obliterate complex MCA aneurysms.•A trajectory perpendicular to the M2 plane is required to apply the clips.•Perpendicular application to the M2 plane is sometimes challenging.•The present technique allows perpendicular application of clips to the M2 plane. The interlocking tandem clipping technique allows a surgeon to effectively obliterate the morphologically complex middle cerebral artery aneurysm. However, applying clips perpendicular to the M2 plane is sometimes challenging, even after meticulous arterial dissection and wide dissection of the Sylvian fissure. We present herein a surgical case of a middle cerebral artery aneurysm, and demonstrate a feasible method by which to rotate the M2 plane and apply the clip perpendicular to the M2 plane. A 44-year-old woman presenting with severe headache was admitted to our hospital. Cerebral digital subtraction angiography showed a small saccular aneurysm arising from the left M2 bifurcation. Due to aneurysm neck overhang of the posterior aspect of the bifurcation, the base of the aneurysm was likely to remain following simple parallel clipping of the efferent artery. Therefore, an interlocking tandem clipping technique was considered. Clip application was needed perpendicular to the M2 plane, but the M2 plane was not perpendicular in the line of sight, even after meticulous arterial dissection. We pushed the superior division of the middle cerebral artery inferiorly and pulled the artery medially using an aspiration tube, which allowed the M2 plane to be rotated medially. This allowed application of both a straight mini-clip and an angled fenestrated mini-clip perpendicular to the M2 plane, resulting in successful aneurysm obliteration without a remnant. The presented feasible method allows easy rotation of the M2 plane and application of the clip perpendicular to the M2 plane.