The frontotemporosphenoidal craniotomy, usually denominated pterional craniotomy, was first described by Yasargil in 1975 and is one of the earliest landmarks of the advents of microneurosurgery [1][2][3] . This approach enables, specifically, the exposure of the entire frontoparietal operculum 4,5 , the opening of the entire sylvian fissure 6,7 and all anterior cisterns of the encephalon base 2,5 , which makes both the pterional craniotomy and the transylvian approach the widest used techniques in today's neurosurgery practice.Over the past decades, the pterional craniotomy has undergone a systematization modified by several authors, what also gave rise to more extended types of craniotomies 8,9 . Among then, the supraorbital craniotomy 10 and the orbitofrontozygomatic craniotomy 10-13 stands out. This review offered a detailed description of the technique we use nowadays for this procedure, with modifications arising from its extensive use since its initial proposal, seeking to optimize all its stages, the access and opening of the cisterns, as well as minimize brain retraction. DESCRIPTION OF PROCEDUREPositioning -the patient should be placed supine, with the shoulder at the edge of the surgical table in a neutral position, and head and neck remain suspended after removal of the head support. The head should be secured by a three-pin skull fixation devise (Mayfield or Sugita model) and must be maintained above the level of the right atrium to facilitate venous return. In order to avoid the head holder position to hinder the surgeon' s procedure, the ipsilateral pin of the operative field should be set on the mastoid region, while the two contralateral pins should be on the contralateral superior temporal line, above the temporal muscle, that should not be transfixed. The pin corresponding to the ipsilateral mastoid and the most anterior one corresponding to the contralateral superior temporal line must be in parallel position to prevent any head movement, especially during future traction of cranial wraps made with the aid of fish-hooks.There is a sequence of five movements for the positioning of the head: traction, lifting, deflection, rotation and torsion. ABSTRACTThis review intended to describe in a didactic and practical manner the frontotemporosphenoidal craniotomy, which is usually known as pterional craniotomy and constitute the cranial approach mostly utilized in the modern neurosurgery. This is, then, basically a descriptive text, divided according to the main stages involved in this procedure, and describes with details how the authors currently perform this craniotomy.Key words: craniotomy, microsurgery, neurosurgery. RESUMOA presente revisão visou descrever de forma didática e prática a realização da craniotomia frontotemporoesfenoidal, usualmente denominada pterional, que constitui a craniotomia mais utilizada na prática neurocirúrgica atual. Trata-se, portanto, de um texto fundamentalmente descritivo, dividido conforme as principais etapas envolvidas na realização desse procedimento, que mostr...

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

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OBJECTIVE The authors report a novel surgical route from a superior anatomical aspect-the contralateral anterior interhemispheric-transcallosal-transrostral approach-to a lesion located in the subcallosal region. The neurosurgical approach to the subcallosal region is challenging due to its deep location and close relationship with important vascular structures. Anterior and inferior routes to the subcallosal region have been described but risk damaging the branches of the anterior cerebral artery. METHODS Three formalin-fixed and silicone-injected adult cadaveric heads were studied to demonstrate the relationships between the transventricular surgical approach and the subcallosal region. The surgical, clinical, and radiological history of a 39-year-old man with a subcallosal cavernous malformation was retrospectively used to document the neurological examination and radiographic parameters of such a case. RESULTS The contralateral anterior interhemispheric-transcallosal-transrostral approach provides access to the subcallosal area that also includes the inferior portion of the pericallosal cistern, lamina terminalis cistern, the paraterminal and paraolfactory gyri, and the anterior surface of the optic chiasm. The approach avoids the neurocritical perforating branches of the anterior communicating artery. CONCLUSIONS The contralateral anterior interhemispheric-transcallosal-transrostral approach may be an alternative route to subcallosal area lesions, with less risk to the branches of the anterior cerebral artery, particularly the anterior communicating artery perforators.

This paper aims to describe the performance of the pretemporal craniotomy performed didactically from 2002 to 2012 in eighty patients. It is therefore a fundamentally descriptive text, organized in the sequence of the main stages in which such a craniotomy is performed, and describing in detail the technique with which this group of evolutionarily authors came to accomplish the task.

Objective: To study the ideal patient's head positioning for the anterior circulation aneurysms microsurgery. Method: We divided the study in two parts. Firstly, 10 fresh cadaveric heads were positioned and dissected in order to ideally expose the anterior circulation aneurysm sites. Afterwards, 110 patients were submitted to anterior circulation aneurysms microsurgery. During the surgery, the patient's head was positioned accordingly to the aneurysm location and the results from the cadaveric study. The effectiveness of the position was noted. Results: We could determine mainly two patterns for head positioning for the anterior circulation aneurysms. Conclusion: The best surgical exposure is related to specific head positions. The proper angle of microscopic view may minimize neurovascular injury and brain retraction.Keywords: cerebral aneurysm, head positioning, anatomical landmarks, anterior circulation arteries, microsurgery. RESUMOObjetivo: Estudar o posicionamento da cabeça para a cirurgia de aneurismas cerebrais da circulação anterior. Método: Dividimos o estudo em duas partes. Inicialmente, dez cabeças de cadáveres frescos foram posicionadas e dissecadas de modo a expor, de maneira ideal, os principais sítios de aneurismas na circulação anterior do cérebro. Posteriormente, 110 pacientes foram submetidos a microcirurgia para clipagem de aneurismas cerebrais da circulação anterior. Durante as cirurgias, as cabeças foram posicionadas de acordo com a localização específica de cada aneurisma e o resultado obtido no estudo dos cadáveres. Cada paciente teve sua posição avaliada quanto a sua eficácia. Resultados: Obtivemos basicamente dois padrões de posicionamento da cabeça para cirurgias de aneurismas cerebrais da circulação anterior. Conclusão: A melhor exposição cirúrgica está relacionada à posição específica da cabeça para cada localização aneurismática. O ângulo de visão microscópica adequado minimiza lesões neurovasculares e a excessiva retração cerebral.Palavras-chave: aneurisma cerebral, posicionamento da cabeça, reparos anatômicos, artérias da circulação anterior, microcirurgia.

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The cerebellum is an exquisite anatomic structure within the human brain, which needs to be considered from the surgical standpoint because of its functional importance and common pathologies that affect this area 1 . It is possible to reach the cerebellum avoiding damaging neural structures by approaches which target tentorial, petrosal, or suboccipital surfaces. Each has its microsurgical particularities in order to reach the desired region and preserve neural structures 2 . In this article, we have presented the microsurgical anatomy of the suboccipital and supracerebellar approaches to the cerebellar surfaces using comprehensives anatomic and functional relations with the final objective of performing better operations with less damage to the cerebellar nucli and important deep pathways. MetHODSThe dentate nucleus, cerebellar peduncles and their relationship with others cerebellar structures were studied in 20 adult cerebellar hemispheres, 12 male and 8 female corpses, obtained from São Paulo death verification service using X3 to X40 magnifications. AbStrActObjective: To define the anatomy of dentate nucleus and cerebellar peduncles, demonstrating the surgical application of anatomic landmarks in cerebellar resections. Methods: Twenty cerebellar hemispheres were studied. Results: The majority of dentate nucleus and cerebellar peduncles had demonstrated constant relationship to other cerebellar structures, which provided landmarks for surgical approaching. The lateral border is separated from the midline by 19.5 mm in both hemispheres. The posterior border of the cortex is separated 23.3 mm from the posterior segment of the dentate nucleus; the lateral one is separated 26 mm from the lateral border of the nucleus; and the posterior segment of the dentate nucleus is separated 25.4 mm from the posterolateral angle formed by the junction of lateral and posterior borders of cerebellar hemisphere. Conclusions: Microsurgical anatomy has provided important landmarks that could be applied to cerebellar surgical resections.Key words: cerebellum, anatomy, neurosurgery.reSuMO Objetivo: Definir a anatomia do núcleo denteado e dos pedúnculos cerebelares, demonstrando a aplicação dos marcos anatômicos em cirurgias cerebelares. Métodos: Foram estudados 20 hemisférios cerebelares. Resultados: A maioria dos núcleos denteados e pedúnculos cerebelares demonstraram relação anatômica constante com outras estruturas cerebelares, fato que proporcionou o estabelecimento de marcos anatômi-cos específicos a serem utilizados em acessos cirúrgicos. O bordo lateral do núcleo denteado é separado da linha média em 19,5 mm em ambos os hemisférios cerebelares. O bordo posterior do córtex é separado do segmento posterior do núcleo denteado por 23,3 mm. O bordo lateral do córtex é separado do bordo lateral do núcleo por 26 mm e o segmento posterior do núcleo denteado é separado por 25,4 mm do ângulo posterolateral, que é formado pela junção dos bordos lateral e posterior do hemisfério cerebelar. Conclusões: O estudo da anatomia microcirúrgic...