An incidence of anteroinferior cerebellar artery/posteroinferior cerebellar artery anatomic variants penetrating the subarcuate fossa dura: operative technique and identification with 3-dimensional fast imaging employing steady-state acquisition magnetic resonance imaging.

OBJECTIVE: This case series reports an incidence of anomalous vascular anatomy within the cerebellopontine angle. The relevant literature effectively describes techniques for mobilization yet underestimates the incidence. There has been no literature on the use of magnetic resonance imaging (MRI) to preoperatively identify this anatomic variant. METHODS: We identify 8 cases of anomalous vascular anatomy within the cerebellopontine angle over a period of 6 years. They were uniformly identified through a retrosigmoid approach. Retrospective review of available 3-dimensional fast imaging employing steady-state acquisition (3D-FIESTA) sequences was performed. Intraoperative video capture of technique for mobilization was obtained. Institutional neurosurgical database review identified retrosigmoid craniotomies performed by the senior surgeon. RESULTS: We identify 8 of 192 cases (4.2%) as having this anomalous vascular anatomy. This aberrant vascular loop resulted in subtotal resection in 3 of 8 cases (37.5%) and significant morbidity in 1 of 8 cases (12.5%). The retrospective review of the 3D-FIESTA MRI sequences positively identified this aberrant vascular course in 5 of 5 cases (100%). The digital video recording is of high quality and demonstrates proper technique for mobilization. CONCLUSION: The presence of this vessel creates the potential for technical difficulty and significant complications. We report the incidence and techniques of mobilization. This variant can potentially be identified on preoperative 3D-FIESTA MRI sequences. Knowledge of this anatomy may guide neurosurgeons in their case preparation.