The relationship between the superior petrosal sinus and the porus trigeminus: an anatomical study.

Object During intracranial approaches to the skull base, vascular relationships are important. One relationship that has received scant attention in the literature is that between the superior petrosal sinus (SPS) and the opening of the Meckel cave (that is, the porus trigeminus). Methods Cadaver dissections were performed in 25 latex-injected adult cadaveric heads (50 sides). Specifically, the relationship between the SPS and the opening of the Meckel cave was observed. The goal was to enhance knowledge of the relationship between the SPS and the opening of the Meckel cave. Results Of the 50 sides, 68%, 18%, and 16% of SPSs traveled superior to, inferior to, and around the opening to the Meckel cave, respectively. In the latter cases, a venous ring was formed around the proximal trigeminal nerve. No sinus entered the Meckel cave. In general, the porus trigeminus was narrowed on sides found to have an SPS that encircled this region. Sinuses that traveled only inferior to the porus were in general smaller than sinuses that traveled superior or encircled this opening. No statistically significant differences were noted between the various sinus relationships and sex, age, or side of the head. Conclusions Knowledge of the relationship between the SPS and the opening of the Meckel cave may be useful to the skull base surgeon. Based on this study, some individuals may retain the early embryonic position of their SPS in relation to the trigeminal nerve.