This article intends to describe in a didactical and practical manner the suboccipital far-lateral craniotomy. This is then basically a descriptive text, divided according to the main stages involved in this procedure, and that describes with details how the authors currently perform this craniotomy.Keywords: neurosurgery, craniotomy, microsurgery, far-lateral approach.RESUMO O presente artigo visa descrever de forma didática e prática a realização da craniotomia suboccipital extremo-lateral. Trata-se, portanto, de um texto fundamentalmente descritivo, dividido conforme as principais etapas da realização dessa craniotomia, e que descreve com detalhes a técnica com que o presente grupo de autores evolutivamente veio a realizá-la.Palavras-chave: neurocirurgia, craniotomia, extremo-lateral, microcirurgia.Approaching lesions located in the lower clivus and at the anterior edge of foramen magnum have always presented as a challenge to the neurosurgeon. The majority of these lesions have been approached posteriorly by suboccipital or retrosigmoid craniotomies and anteriorly by trans-oral and through the paranasal sinus approaches. Nevertheless all of then have disadvantages including a great depth of surgical field and an extremely limited lateral exposure 1 . Once the high morbidity and mortality of lesions located at so an important anatomic region, the improvement of these posterior approaches is imperative, in order to increase the surgical exposure and reduce the retraction of neurovascular structures.The far lateral approach is the one composed by the dissection of occipital-cervical muscles with the exposition of suboccipital triangle, the lateral suboccipital craniotomy and finally the exposure of vertebral artery since its entrance into the dura mater 2

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.

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Posterior fossa arteriovenous malformations (AVMs) can be a challenging disease, especially those large in size. AVMs can be treated with a combination of endovascular treatment and microsurgery. Here, the authors present the case of a 16-year-old female patient with progressive dizziness and episodic syncope. The workup of the patient showed a hemispheric cerebellar AVM, Spetzler-Martin grade IV. She underwent combined treatment (endovascular and microsurgery) with no complications and cure of the malformation.The video can be found here: https://youtu.be/rNw_Kyd76Mg

Brainstem arteriovenous malformations (AVMs) represent 2% to 7% of all brain AVMs. [1][2][3] Compared with other locations, a greater proportion present with hemorrhage and subsequently have a worse prognosis. 2,4 Surgery has been associated with poor outcomes, 5,6 with parenchymal AVMs associated with higher rates of incomplete resection and morbidity compared with subpial type. 7 Concerns over latency from radiosurgery to obliteration after hemorrhage, potential for incomplete obliteration, and risk of adverse radiation effects are cited by proponents of surgery. [6][7][8][9] Limited access to the anterior brainstem and difficulty controlling deep feeders add to the complexity of surgery. Previous authors have recommended occlusion in situ for parenchymal brainstem AVMs. 9,10 We present a case showing microsurgical management of a parenchymal midbrain AVM. The patient, 46-year-old man, presented with an acute headache and diplopia following hemorrhage 1 year prior. Examination revealed bilateral ptosis, conjugate upgaze palsy, right abduction paresis, and normal light and accommodation reflexes in keeping with a dorsal midbrain lesion. Magnetic resonance and digital subtraction angiography confirmed a compact midbrain AVM (1.6 cm) extending from the pulvinar thalamus to the right quadrigeminal plate, supplied by posterior thalamoperforating, right posteromedial choroidal and branches of the P3 segment and SCA posteriorly, and drainage by the vein of Galen. Tractography showed displacement of the long tracts. A combination of a posteroanterior microsurgical approach and selective anteroposterior embolization of feeders allowed complete resection with no new deficits. The patient consented to the procedure. We demonstrated that brainstem AVMs can safely be resected in experienced hands, with selective preoperative embolization, use of indocyanine videoangiography, and intraoperative neurophysiological monitoring. 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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