Unilateral Approach for Bilateral Middle Cerebral Artery Aneurysms Assisted by Preoperative Understanding of Aneurysm Wall Properties: Two-Dimensional Operative Video.

Unruptured middle cerebral artery (MCA) aneurysms often exist bilaterally, and a unilateral approach for bilateral MCA aneurysms has been reported; however, this remains challenging because there are various technical nuances. Wall properties have been reported to be an important issue for this strategy. Atherosclerotic changes in the aneurysm wall can make clipping difficult. We present a video case demonstrating clipping of bilateral MCA aneurysms via a unilateral craniotomy assisted by preoperative understanding of the aneurysm wall properties using computational fluid dynamic analysis (Video 1). A 71-year-old woman had bilateral MCA bifurcation aneurysms. The oscillatory shear index color map by computational fluid dynamic analysis demonstrated that the contralateral MCA aneurysm did not have a high oscillatory shear index area in the dome, which means that there was no wall thickening, and the ipsilateral MCA aneurysm had scattered high oscillatory shear index areas, which were expected to have extreme wall thickening. After pterional craniotomy, the sylvian fissure was widely opened. As expected, the contralateral MCA aneurysm did not have a thick-walled region, enabling simple neck clipping using a straight clip. In contrast, the ipsilateral MCA aneurysm had thick-walled areas, as predicted, necessitating a multiple clip application. Postoperatively, the patient was discharged without any neurological deficits. Prediction of aneurysm wall properties using computational fluid dynamic analysis could assist in determining clippability of intracranial aneurysms, especially for aneurysms approached by narrow and deep surgical fields, such as contralateral MCA aneurysms. The patient consented to the procedure and the publication of their images.