Lateral Supracerebellar, Infratentorial Approach for a Large Midbrain Cavernous Malformation: 2-Dimensional Operative Video.

Management of midbrain cavernous malformations (CVMs) is not well-defined. In select patients with symptomatic lesions and favorable anatomy, microsurgical treatment may be effective. This video illustrates a case of a Lawton grade 4, hemorrhagic midbrain CVM that was surgically resected through a lateral supracerebellar infratentorial approach.(1) A 26-yearoldman presented with left-sided weakness and numbness, right trochlear nerve palsy, and gait disturbances. Neuroimaging demonstrated a hemorrhagic lesion in the right midbrain that crossedmidlinewith a tegmental pial presentation. The decision was made to proceed with surgery to minimize the risk of future, potentially devastating hemorrhagic events for this symptomatic lesion.(2,3) After the patient was placed in a sitting position, C-shaped incision was made, and extended retrosigmoid craniotomy was performed. Subarachnoid dissection exposed the superior cerebellar artery, trochlear nerve, and dorsolateral midbrain. Using hemosiderin staining and navigation, a vertical incision was made into the lateral mesencephalic sulcus above the trochlear nerve, and piecemeal resection of the CVM was performed. Postoperatively, the patient was at his neurological baseline. There were no complications, and he was discharged to rehab. At 6-week follow-up, the patient's preoperative symptoms had resolved except for persistent trochlear nerve palsy. Brainstem CVMs comprise 20% of cerebral CVMs.(4) Observation and gamma knife, a controversial treatment for cavernomas, were considered. This patient's young age and intermediate-grade, symptomatic lesion with repeat hemorrhage ultimately favored microsurgical treatment.(5) Ultimately, a supracerebellar infratentorial approach was ideal for resecting this CVM with a tegmental pial presentation. All embedded figures in the video were created by Tina Wang, 2022, University of Maryland, Baltimore. "Lateral Supracerebellar, Infratentorial Approach for a LargeMidbrain Cavernous Malformation," Operative Neurosurgery (created for this article submission), 2022, published with permission from (c) University of Maryland, Baltimore. Consent was obtained for the surgery in the preoperative period.