Acousticofacial-glossopharyngeal triangle: an anatomic model for rapid surgical orientation

The cerebellopontine angle (CPA) poses a surgical challenge due to the complexity and variation of its associated structures. This study examined the relationship between the glossopharyngeal nerve (CN IX) and the acousticofacial complex (AFC). Retrosigmoid suboccipital dissections were preformed on 10 cadaveric specimens. A triangle formed by the AFC, CN IX, and the skull base was consistently observed. The cisternal portions of the AFC and CN IX formed two sides of the triangle. The base was formed by a line traversing the respective dural portals of these nerves at the skull base. Triangular proportions were utilized to predict distances from five points along the course of CN IX to a corresponding point along the course of the AFC. Predicted distances were not statistically different when compared with cadaveric measurements in all 10 specimens (p > 0.05). A table of predicted distances between CN IX and the AFC at all five points along CN IX was developed, revealing a quantitative model to predict the native location of the AFC in the lateral pontine cistern. The triangle and predicted location of the AFC can serve as points of reference for the identification and preservation of these structures in CPA surgery.