Microsurgical Resection of a Lateral Pontine Arteriovenous Malformation Masquerading as a Cavernous Malformation: 2-Dimensional Operative Video.

Although cavernous malformations (CMs) often demonstrate characteristic T2 heterogeneity and gadolinium enhancement, whereas arteriovenous malformations (AVMs) appear as tangles of T2 hypointense flow voids, small lesions in deep locations may have equivocal features on preoperative imaging.1-4 This video presents an unusual case of a lateral pontine AVM masquerading as a CM. The patient presented with sudden-onset headache, dizziness, double vision, and left facial numbness. Diagnostic imaging findings suggested a hemorrhagic left lateral pontine mass lesion, most consistent with brainstem CM. Resection through a left extended retrosigmoid craniotomy was recommended. Patient consent was obtained. During dissection, a prominent petrosal vein tributary was noted to be arterialized, which was concerning for AVM. Indocyanine green videoangiography (ICG-VA) was performed to confirm the diagnosis, and the intraoperative plan was dynamically adjusted in accordance with the principles of AVM resection. The small superficial feeding arteries were identified and disconnected, and the nidus was dissected circumferentially with the pial resection technique. After dearterialization, the draining petrosal vein was noted to darken, and repeat ICG-VA confirmed complete occlusion of the AVM without residual shunting. The patient recovered well, with no neurological deficits, and postoperative angiography confirmed complete resection of the Spetzler-Martin grade III AVM. Key learning points for this unusual case include the importance of dynamic interpretation of intraoperative findings, openness to alterations of the surgical plan when integrating new diagnostic information, and the integration of ICG-VA as a critical tool for differentiating CMs and AVMs during microsurgical resection. Images in Surgical Video © 2024 Barrow Neurological Institute. Used with permission.