Arteriovenous malformations in the brainstem are among the most challenging to manage. They represent between 7% and 15% of all brain arteriovenous malformations (AVMs). The high risk of hemorrhage eloquence and increased susceptibility to adverse radiation effects restricts the management of such cases to experienced centers. 1,2 The latency associated with radiosurgery, poor results from embolization as primary therapy all make surgery a favored option in experience hands. 3 A good understanding of the anatomy, arterial supply, and venous drainage of this region is required to safely manage pathology located here. 4,5 There are 2 main patterns of AVMs seen in the midbrain. A type restricted to the pial with exophytic appearance and a second truly parenchymal location. 6 The goal of surgery is to eliminate the risk of hemorrhage and avoid ocular motility and morbidity. An occipital transtentorial approach is often considered when a steep tentorial angle is encountered. [6][7][8] We present a video case of the surgical resection of an exophytic quadrigeminal plate AVM. The patient, a 42-year-old man, presented with a sudden and intense headache, without neurological deficit. MRI and digital subtraction angiography revealed a 2 cm AVM located in the right inferior colliculi supplied by branches of the posterior cerebral artery with early venous drainage into the vein of Galen. The patient consented to the procedure. We demonstrate the supracerebellar infratentorial corridor with a limited resection of the quadrangular lobule to remove the AVM. The case highlights the key anatomic landmarks required to safely modify this classic approach.

Neurosurgical training outside the operating room has become a priority for all neurosurgeons around the world. The exponential increase in the number of publications on training in neurosurgery reflects changes in the environment that future neurosurgeons are expected to work in. In modern practice, patients and medicolegal experts demand objective measures of competence and proficiency in the growing list of techniques available to treat complex neurosurgical conditions. It is important to ensure the myriad of training models available lead to tangible improvements in the operating room. While neuroanatomy textbooks and atlases are continually revised to teach the aspiring surgeon anatomy with a three-dimensional perspective, developing technical skills are integral to the pursuit of excellence in neurosurgery. Parapharsing William Osler, one of the fathers of neurosurgical training, without anatomical knowledge we are lost, but without the experience and skills from practice our journey is yet to begin. It is important to constantly aspire beyond competence to mastery, as we aim to deliver good outcomes for patients in an era of declining case volumes. In this article, we discuss, based on the literature, the most commonly used training models and how they are integrated into the treatment of some surgical brain conditions.

Arteriovenous malformations (AVM) in the posterior fossa represent 2% to 15% of all brain AVMs, are often smaller, and have a higher risk of hemorrhage. [1][2][3][4] The presence of a single draining vein, venous stenosis, and high-flow fistulae increases hemorrhage risk but also venous congestion. [3][4][5][6] AVM associated with high-flow fistula can be managed surgically, radiosurgically, or endovascularly. 7-10 Embolization of the associated fistula is reported to be safer than embolization of the nidus. 7 Surgery is favored in the symptomatic patient when concerns over the latency from radiosurgery to obliteration and overshooting the shunting zone during embolization predominate. 4,11 For small AVM with high-flow shunts localization of the nidus and fistulous connection is the main challenge. Sinus skeletonization in complex dural arteriovenous fistula is a reported technique. 12 We adapt this technique to delineate and disconnect a subpial posterior fossa AVM with high-flow fistula. We present a video case of an obese male in his 50s with hypertension and end-stage renal disease who presented with a 9-month history of progressive spastic quadriparesis. The patient consented to the procedure. Examination revealed grade 2 power on the left and grade 4 on the right with brisk reflexes. MRI showed T2 signal hyperintensity in the pons, and digital subtraction angiography confirmed an AVM overlying the culmen of the vermis with feeders from the S3 segment of the superior cerebellar artery, draining into the precentral vein. We demonstrated that surgical management of micro-AVMs with associated high-flow fistulae can be safely achieved in experienced hands using technique of vein skeletonization guided by indocyanine green angiography. The patient signed the Institutional Consent Form, which states that he accepts the procedure and allows the use his images and videos for any type of medical publications in conferences and/or scientific articles.

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