Three-Dimensional Quantitative Analysis of the Brainstem Safe Entry Zones Based on Internal Structures.

OBJECTIVE: Brainstem safe entry zones (EZs) are gates to access the intrinsic pathology of the brainstem. We performed a quantitative analysis of the intrinsic surgical corridor limits of the most commonly used EZs and illustrated these through an inside perspective using 2-dimensional photographs, 3-dimensional photographs, and interactive 3-dimensional model reconstructions. METHODS: A total of 26 human brainstems (52 sides) with the cerebellum attached were prepared using the Klingler method and dissected. The safe working areas and distances for each EZ were defined according to the eloquent fiber tracts and nuclei. RESULTS: The largest safe distance corresponded to the depth for the lateral mesencephalic sulcus (4.8 mm), supratrigeminal (10 mm), epitrigeminal (13.2 mm), peritrigeminal (13.3 mm), lateral transpeduncular (22.3 mm), and infracollicular (4.6 mm); the rostrocaudal axis for the perioculomotor (11.7 mm), suprafacial (12.6 mm), and transolivary (12.8 mm); and the mediolateral axis for the supracollicular (9.1 mm) and infracollicular (7 mm) EZs. The safe working areas were 46.7 mm2 for the perioculomotor, 21.3 mm2 for the supracollicular, 14.8 mm2 for the infracollicular, 33.1 mm2 for the supratrigeminal, 34.3 mm2 for the suprafacial, 21.9 mm2 for the infrafacial, and 51.7 mm2 for the transolivary EZs. CONCLUSIONS: The largest safe distance in most EZs corresponded to the depth, followed by the rostrocaudal axis and, finally, the mediolateral axis. The transolivary had the largest safe working area of all EZs. The supracollicular EZ had the largest safe area to access the midbrain tectum and the suprafacial EZ for the floor of the fourth ventricle.

Microsurgical Treatment for a Ruptured Posterior Inferior Cerebellar Artery Aneurysm: A 3-Dimensional Surgical Video and Anatomic Landmarks Review.

Aneurysms are the most frequent issue for the posterior inferior cerebellar artery (PICA). PICA aneurysms account for 1.4% to 4.5% of all intracranial aneurysms.1-3 Although the majority of PICA aneurysms arise from their junction with the vertebral artery, they can be found in any of 5 segments.4,5 Although PICA is more prone to form nonsaccular aneurysms than other intracranial arteries, ruptured aneurysms are usually saccular.6 Nearly all PICA aneurysms are located intracranially, above the foramen magnum. Extracranial PICA aneurysms are rare, with few reports in literature.7 Microsurgical clipping remains a good treatment alternative for these aneurysms. Higher risk of rerupture has even been reported with embolization of the distal PICA aneurysm with parent artery preservation.8 Here we present the case of a 64-year-old male patient who presented right after a thunderclap headache, followed by a temporary loss of consciousness and disorientation. He was diagnosed with a modified Fisher 4 and Hunt and Hess 2 subarachnoid hemorrhage and found to have a partially thrombosed left PICA saccular aneurysm of the caudal loop just below the foramen magnum. The lesion was approached via a midline suboccipital craniotomy with C1 laminectomy. Microsurgical clipping of the aneurysm was performed without any complications (Video 1). Postoperatively, the patient was discharged without neurologic deficits. We present the first surgical video of the necessary steps in order to perform a microsurgical clipping of an extracranially located caudal loop PICA aneurysm through a midline suboccipital craniotomy with C1 laminectomy.

Third ventricle colloid cysts: An endoscopic case series emphasizing technical variations.

BACKGROUND: Colloid cyst treatment with purely endoscopic surgery is considered to be safe and effective. Complete capsule removal for gross total resection is usually recommended to prevent recurrence but may not always be safely feasible. Our objective was to assess the results of endoscopic surgery using mainly aspiration and coagulation without complete capsule resection and discuss the rationale for the procedure. METHODS: A retrospective review was conducted of 45 consecutive symptomatic patients with third ventricle colloid cysts that were surgically treated with purely endoscopic surgery from 1997 to 2018. RESULTS: Mean age was 35.4 years. Male-to-female ratio was 1:1. Clinical presentation included predominantly headache (80%). Transforaminal was the most used route (71.1%) followed by transeptal (24.5%) and interforniceal (4.4%). Capsule was intentionally not removed in 42 patients (93.3%) and cyst remnants were absent on postoperative MRI in 36 (85%). Mild complications occurred in 8 patients (17.8%). Surgery was statistically associated with cyst volume and ventricular size reduction. There were no serious complications, shunts or deaths. Follow-up did not show any recurrence or remnant growth that needed further treatment. CONCLUSION: Gross total resection may not be the main objective for every situation. Subtotal resection without capsule removal seems to be safer while preserving good results, especially in a limited resource environment. Remnants left behind should be followed but tend to remain clinically asymptomatic for the most part. Surgical planning allows the surgeon to choose among the different resection routes and techniques available. Decisions are predominantly based on preoperative imaging and intraoperative findings.

Idiopathic Ventral Spinal Cord Herniation: Video Report and Systematic Review.

BACKGROUND: Idiopathic ventral spinal cord herniation (ISCH) is a rare disease; however, it is an important differential diagnosis. Its treatment presents some controversies. CASE DESCRIPTION: We report on a 55-year-old woman who had been presenting with relevant back pain and leg weakness for the past 3 years and urinary incontinence for the past 3 months. Clinical examination disclosed paresis on the right inferior limb and right foot, as well as a T6-level painful hypoesthesia. Magnetic resonance imaging disclosed a T4/T5 ISCH. The patient underwent surgical decompression. During the procedure, we opened the arachnoid and cut the dentate ligaments of the spine, which considerably improved the mobility and safety of the procedure. In the early follow-up, our patient presented a partial improvement regarding the paresis grades and hypoesthesia pain relief on the left side. A video showing the surgical procedure and case evolution is presented. We also assembled literature reviews to compare our case with others. ISCH is becoming a more recognized cause of progressive thoracic myelopathy. However, this condition is still frequently misdiagnosed. Magnetic resonance imaging is the key for diagnosis. The objective of surgical treatment is to prevent myelopathy progression. The technique presented in this report is an appropriate surgical option, once it is a safer way to identify and treat the defect. The neurologic condition usually improves greatly after surgical treatment, especially when the patient presents positive predictive factors. CONCLUSIONS: ISCH is being more recognized. The technique presented is an appropriate surgical option.

Microsurgical Clip Placement for a Giant Anterior Communicating Artery Aneurysm With Intraluminal Thrombus: 2-Dimensional Operative Video.

Giant brain aneurysms account for approximately 5% of all intracranial aneurysms. Although treatment modalities can vary widely, none is ideal for every patient. Endovascular treatment is usually preferred, especially when the large size of the aneurysm limits visualization of the brain parenchyma and parent vessels that arise from the aneurysm, making surgical clip placement across the neck a difficult task. However, despite the higher chances of morbidity, microsurgery is an effective treatment modality due to lower recurrence rates. Surgically, a wide neck, calcifications, or atheroma are complicating factors to be considered while planning the best treatment. Thus, with an appropriate case selection, a favorable outcome is feasible in most cases. Here, we present the case of a 27-yr-old female who presented with a severe headache for 7 mo and 3 mo of progressive left temporal vision loss, which was confirmed by visual field perimetry using the Humphrey visual field analyzer. Magnetic resonance angiography and digital subtraction cerebral angiography showed an anterior communicating artery complex inferiorly and medially oriented aneurysm measuring 25.4 × 16.5 mm, with a 3 mm neck. It was fed by the right A1, associated with a hypoplastic left A1, incorporating the proximal right and left A2 segments, with an intraluminal thrombus and causing mass effect on the optic chiasm and hypothalamus. This video demonstrates the microsurgical steps required to perform this operation, through a right orbitozygomatic craniotomy. At a 3-mo follow-up, the patient was neurological intact without complaints. The patient signed the Institutional Consent Form, which allows the use of his/her images and videos for any type of medical publications in conferences and/or scientific articles.

The Importance of Student Leagues on Medical Training in Neurosurgery and Residency Choice

Introdução Distúrbios neurológicos e neurocirúrgicos são altamente prevalentes no Brasil. O atendimento inicial é realizado por médicos generalistas, o que demonstra a importância dos estudos práticos e teóricos em neurologia e neurocirurgia nos cursos de graduação em medicina. Objetivos Descrever a escolha da especialidade médica dos formandos da Liga Acadêmica de Neurocirurgia da Escola Paulista de Medicina (LNC-EPM) e mapear a composição dos cursos de neurologia e/ou neurocirurgia e a presença de ligas acadêmicas dessas disciplinas nas escolas médicas do Brasil. Métodos Levantamento pessoal ou por rede social com todos os membros da liga de neurocirurgia da EPM de 2007 a 2015 quanto a conclusão do curso e a residência escolhida. Envio de um formulário online para todas as escolas médicas cadastradas no Conselho Federal de Medicina (CFM). Resultados e Discussão Cinquenta e sete graduandos de medicina já participaram da LNC-EPM, sendo que 45 já concluíram a graduação, 6 fizeram neurocirurgia e 5 neurologia. Conseguimos respostas de 128 das 173 escolas médicas cadastradas no CFM. Um total de 91% das escolas respondeu que possuem curso de neurologia estruturado. Esses cursos dividem-se em: 32 exclusivamente teóricos, com 12 abordando a neurocirurgia; 84 teórico-práticos, com 51 abordando a neurocirurgia. Apenas 19% das faculdades apresentam curso próprio estruturado de neurocirurgia, sendo que metade destes é apenas teórico. Um total de 66% das universidades tem liga acadêmica das disciplinas citadas. Conclusão Nota-se que a presença de ligas acadêmicas de neurologia e neurocirurgia em 66% das escolas médicas brasileiras é, muitas vezes, usada para suprir conhecimento teórico-prático que deveria ser abordado na graduação. Infelizmente, apenas 9,5% das escolas tem curso teórico-prático próprio de neurocirurgia na grade curricular, um fato que é preocupante devido à alta prevalência das doenças neurológicas na população.

Endoscopic Treatment of a Third Ventricular Epidermoid Cyst.

Epidermoid cyst is a benign and congenital lesion of ectodermal origin. Traditionally, microsurgical techniques are used to treat these lesions, and their occurrence in the third ventricle is rare. Here, the authors report a case of epidermoid cyst in the third ventricle that presented with signs and symptoms of intracranial hypertension, which was treated safely and effectively using neuroendoscopic surgery.