A Tailored Combined Petrosal Approach for the Resection of a Petroclival Meningioma With Pneumatized Apex: Checkmate to the Trigeminal Nerve: 2-Dimensional Operative Video.

Petroclival meningiomas are a challenge in skull base surgery, despite the advances in the knowledge of this pathology, there are still many controversies regarding their optimal treatment.1 The proximity and adherence to cranial nerves, major vessels such as the basilar artery, and brainstem compression explain the significant surgical risk.2,3 We present the case of a woman with a petroclival meningioma (WHO grade I) and pneumatization of the petrous apex. A tailored combined petrosal approach with a wide pedicled flap was performed for reconstruction of the pneumatized petrous apex. The decision to choose an appropriate surgical approach in this type of tumor depends on multiple factors including the surgeon's skill. We believe that in this particular case the pneumatization of the petrosal apex and the involvement of the trigeminal nerve by the tumor demanded a surgical approach that allowed a 360-degree view of the trigeminal nerve and at all angles of attack on the site of tumor implantation, we call this a checkmate of the trigeminal nerve. Transposition of the trigeminal nerve may be necessary in cases such as the one we present for adequate visualization of the petroclival region. This surgical video discusses the nuances of technique, surgical pearls, and anatomic landmarks in the combined petrosal approach. The patient consented to the procedure and to the publication of her image, and appropriate consent was obtained for publication of the cadaver's image.

The M-Point A Novel Landmark in Middle Fossa Surgery: A Cadaveric Morphometric Study.

BACKGROUND: The arcuate eminence (AE) is an anatomically consistent bony protrusion located on the upper surface of the petrous bone that has been previously studied as a reference for lateral skull base approaches. There is a paucity of information in the neurosurgical literature seeking to improve the safety of the extended middle cranial fossa (MCF) approach using detailed morphometric analysis of the AE. OBJECTIVE: To evaluate the use of the AE as an anatomical landmark to help with early identification of the internal acoustic canal (IAC) in MCF approaches by means of a cadaveric study, using a new morphometric reference termed the "M-point." METHODS: A total of 40 dry temporal bones and 2 formalin-preserved, latex-injected cadaveric heads were used. The M-point was established as a new anatomic reference by identifying the intersection of a line perpendicular to the alignment of the petrous ridge (PR), originating from the midpoint of the AE, with the PR itself. Subsequent anatomical measurements were performed to measure the distance between M-point and IAC. Additional distances, including PR length and the anteroposterior and lateral AE surfaces, were also measured. RESULTS: The mean distance between the M-point and the center of the IAC was 14.9 mm (SD ± 2.09), offering a safe drilling area during an MCF approach. CONCLUSIONS: This study provides novel information on identification of a new anatomic reference point known as the M-point that that can be used to improve early surgical identification of the IAC.