Microsurgical Resection of Tonsillar Arteriovenous Malformation: Operative Video.

Cerebellar arteriovenous malformation (AVM) comprises 10%-15% of intracranial AVMs.1 Rupture often leads to devastating brainstem compression, with mortality reported as high as 67%.2 AVM can be a challenging disease, especially when large in size.3 AVMs can be treated by 1 or a combination of treatment modalities, namely embolization, radiosurgery, or microsurgical resection.4,5 Arterial adhesions to tonsilobulbar and telovelonsilar segments of posterior inferior cerebellar artery (PICA) can be a challenge, increasing bleeding and ischemic risk.6 We present a 2-dimensional video case of a tonsillar AVM. The patient, a previously healthy female in her 20s, presented with a chronic headache. She had no medical history. Initial magnetic resonance imaging revealed a tonsillar AVM classified as Spetzler-Martin grade II. It received its supply from the tonsilobulbar and telovelotonsilar segments of the PICA and drained directly into the precentral vein, transverse sinus, and sigmoid sinus. An angiogram revealed severe venous engorgement-the source of the patient's headache. The AVM was partially embolized 1 month preoperatively. A medial suboccipital telovelar approach was chosen to reduce the working distance and afford a wider corridor to expose the suboccipital surface of the cerebellum.7,8 Complete resection of the AVM was achieved with no additional morbidity. Microsurgery in experienced hands offers the best chance of cure for AVMs. In Video 1, we demonstrate the relationships among the tonsila, biventral lobule, vallecula cerebelli, PICA, and cerebellomedullary fissure as an important anatomic landmark in a safe total resection of a tonsillar AVM.

Posterior-Transcallosal Approach to a Choroidal Fissure Arteriovenous Malformation: Video of Adapting a "Bridging Vein Free" Corridor to This Complex Region.

Choroidal fissure arteriovenous malformations (ChFis-AVMs) are uncommon and challenging to treat due to their deep location and pattern of supply.1 The choroidal fissure lies between the thalamus and fornix, from the foramen of Monroe to the inferior choroidal point.2 AVMs in this location receive their supply from the anterior, lateral posterior choroidal artery and medial posterior choroidal arteries and drain to the deep venous system.3 The anterior-transcallosal corridor to the ChFis is favored due to the ease in opening the taenia fornicis from the foramen Monroe, and it increases in length for lesions located more posteriorly.4-7 We present a case of a posterior ChFis-AVM. The patient, a previously healthy woman in her 20s, presented with a sudden severe headache. She was diagnosed with intraventricular hemorrhage. This was managed conservatively with subsequent magnetic resonance imaging and digital subtraction angiography revealing a ChFis-AVM at the body of the left lateral ventricle, between the fornix and superior layer of the tela choroidae. It received its supply from the left lateral posterior choroidal artery and medial posterior choroidal artery and drained directly into the internal cerebral vein, classified as Spetzler-Martin grade II.8 A posterior-transcallosal approach to the ChFis was chosen to reduce the working distance and afford a wider corridor by avoiding cortical bridging veins (Video 1). Complete resection of the AVM was achieved with no additional morbidity. Microsurgery in experienced hands offers the best chance of cure for AVMs.9 In this case we demonstrate how to adapt the transcallosal corridor to the choroidal fissures for safe AVM surgery in this complex location.

The art of combining neuroanatomy and microsurgical skills in modern neurosurgery.

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.