The pterional transsylvian transtentorial approach to ventrolateral pontine cavernomas: indications and techniques

The authors describe a pterional transsylvian transtentorial approach to the ventrolateral pons based on its clinical application to cavernomas.

Consecutive patients in their database with brain stem cavernomas who underwent surgical removal from April 2009 to December 2012 were retrospectively analyzed. Four patients who underwent anterolateral pontine cavernoma removal via the pterional transsylvian transtentorial approach were included in the current study. The surgical indications, techniques, exposure, and feasibility were analyzed. To make a comprehensive illustration of surgical feasibility and exposure, a fresh, colored-latex-injected cadaveric head specimen was used.

The cavernomas of these four patients were confirmed successful removal by both surgeon's intraoperative views and follow-up magnetic resonance images. Cranial nerve (CN) IV was inadvertently transected in one patient, and transient muscle power decrease occurred in another patient. Based on the surgeons' experiences and anatomy illustration, the pterional transsylvian transtentorial approach enables a wide exposure of the upper ventral pons inferolaterally to the CN V root entry zone, inferiorly to the CN V root entry zone horizontal level, and medially to the basilar artery.

Although a comprehensive comparison with other approaches needs a large patient volume and a prospective designed study, the pterional transsylvian transtentorial approach could be an alternative for ventrolateral pontine cavernomas. The principle for this approach to ventrolateral pontine cavernomas is that if the thinnest parenchyma layer over the cavernoma could be defined in the ipsilateral upper ventrolateral pons, facilitated by an oblique multiangled working space, cavernomas in even the entire ventrolateral pons could be removed.