Resection of the quadrangular lobule of the cerebellum to increase exposure of the cerebellomesencephalic fissure: an anatomical study with clinical correlation.

OBJECTIVE: The lateral aspect of the cerebellomesencephalic fissure frequently harbors vascular pathology and is a common surgical corridor used to access the pons tegmentum, as well as the cerebellum and its superior and middle peduncles. The quadrangular lobule of the cerebellum (QLC) represents an obstacle to reach these structures. The authors sought to analyze and compare exposure of the cerebellar interpeduncular region (CIPR) before and after QLC resection and provide a case series to evaluate its clinical applicability. METHODS: Forty-two sides of human brainstems were prepared with Klingler's method and dissected. The exposure area before and after resection of the QLC was measured and statistically studied. A case series of 59 patients who underwent QLC resection for the treatment of CIPR lesions was presented and clinical outcomes were evaluated at 1-year follow-up. RESULTS: The anteroposterior surgical corridor of the CIPR increased by 10.3 mm after resection of the QLC. The mean exposure areas were 42 mm2 before resection of the QLC and 159.6 mm2 after resection. In this series, ataxia, extrapyramidal syndrome, and akinetic mutism were found after surgery. However, all these cases resolved within 1 year of follow-up. Modified Rankin Scale score improved by 1 grade, on average. CONCLUSIONS: QLC resection significantly increased the exposure area, mainly in the anteroposterior axis. This surgical strategy appears to be safe and may help the neurosurgeon when operating on the lateral aspect of the cerebellomesencephalic fissure.

Intrinsic epidermoid cyst of the brainstem in children-review and case report.

PURPOSE: The study aimed to summarize all published cases of intrinsic brainstem epidermoid cysts in a timeline to highlight the specific characteristics and individualize the disease, in addition to discussing the best treatment used. METHODS: The scientific literature on pediatric cases of intrinsic epidermoid cysts of the brainstem was analyzed. We present the case of a 1.5-year-old male with incidental presentation, who was treated with gross total resection. We summarize all previously published cases to individualize the disease. RESULTS: We identified 21 patients, including 10 boys and 11 girls, with a mean age of 4.85 (1-15) years at the time of surgery. The most frequent symptoms were cranial nerve palsy (71.4%), pyramidal tract deficit (57.14%), and headache (52.38%). Among the affected cranial nerves, VII was the most frequently reported in 10 patients. CONCLUSION: Brainstem epidermoid cysts are extremely rare pathologies with relevant age involvement in young children. The treatment objective should be the maximum resection of the lesion through a careful approach and with the appropriate tools for the functional preservation of the patient.

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 Resection of a Left Cerebral Peduncle Cavernous Malformation: 3-Dimensional Operative Video.

Brainstem cavernous malformations are challenging lesions considering the numerous eloquent structures frequently related. Surgical resection is the preferred treatment if the patient is symptomatic and the lesion can be safely resected. We present the case of a right-handed 38-yr-old female, presenting with progressive impairment of her handwriting. Physical examination showed a right-sided grade 4/5 hemiparesis. Preoperative imaging was suggestive of a left cerebral peduncle cavernous malformation with a recent area of hemorrhage. The most superficial portion of the lesion was on the surface of the brainstem in the supratrigeminal safe entry zone of the pons. A frontotemporal craniotomy was performed, followed by a pretemporal transtentorial approach. Prior to performing brainstem incision, the area was stimulated, and no motor evoked potential was recorded. The hematoma was then evacuated, and the cavernous malformation was dissected and removed. The capsule was also dissected and removed, using neurophysiological monitoring to guide this procedure. The lesion was completely resected, and the patient was discharged on postoperative day 7 with a right-sided hemiparesis grade 3/5, which improved to grade 5/5 after 4 mo. The patient presented an improvement of her symptoms, with no new neurological deficits. Brainstem cavernomas can be safely removed in selected cases, using the adequate safe entry zone and the appropriate surgical approach. The pretemporal route can be used to reach the anterolateral aspect of the upper part of the brainstem, as it combines the advantages of both transsylvian and subtemporal approaches. An informed consent was obtained from the patient for publication of this operative video.

Endoscopic Endonasal Odontoidectomy: Nuances of Neurosurgical Technique / Odontoidectomia endoscópica endonasal: nuances da técnica cirúrgica

Odontoidectomy is the treatment of choice for some diseases that cause irreducible ventral compression of the brainstem. In this study, we present our series emphasizing the technical nuances of endoscopic endonasal odontoidectomy

Odontoidectomia é o tratamento de escolha para algumas doenças que cursam com compressão irredutível do tronco encefálico. Neste trabalho, apresentamos nossa série enfatizando as nuances da técnica cirúrgica da odontoidectomia por via endonasal endoscópica.

Stereotactic Drainage of Brainstem Abscess With the BrainLab Varioguide™ System and the Airo™ Intraoperative CT Scanner: Technical Case Report.

BACKGROUND AND IMPORTANCE: Stereotactic biopsies or needle aspirations of posterior fossa lesions are technically challenging. Here we report a novel technique for performing these procedures employing the Airo™ intraoperative computed tomographic (CT) scanner and the VarioGuide™ articulated arm (BrainLab, Munich, Germany). CLINICAL PRESENTATION: A 62-yr-old woman presented with an irregularly shaped, enhancing lesion of the left pons/middle cerebellar peduncle. Slowed diffusion on magnetic resonance imaging suggested an abscess, but no definitive infectious agent/source could be identified. When the patient deteriorated despite broad-spectrum antibiotic therapy, she was taken to the operating room for stereotactic drainage of the abscess employing the described technique. A specific infectious agent (Eikenella corrodens) was identified from the aspirate, allowing for tailored antibiotic therapy. The procedure was well tolerated and the patient made a full recovery with minimal neurological sequelae. CONCLUSION: The combination of the Airo™ intraoperative CT and the Varioguide™ articulated arm allows for safe, accurate, and efficient targeting of posterior fossa lesions.

Surgical approaches for brainstem tumors in pediatric patients.

PURPOSE: To analyze the pathways to brainstem tumors in childhood, as well as safe entry zones. METHOD: We conducted a retrospective study of 207 patients less than 18 years old who underwent brainstem tumor resection by the first author (Cavalheiro, S.) at the Neurosurgical Service and Pediatric Oncology Institute of the São Paulo Federal University from 1991 to 2011. RESULTS: Brainstem tumors corresponded to 9.1 % of all pediatric tumors operated in that same period. Eleven previously described "safe entry zones" were used. We describe a new safe zone located in the superior ventral pons, which we named supratrigeminal approach. The operative mortality seen in the first 2 months after surgery was 1.9 % (four patients), and the morbidity rate was 21.2 %. CONCLUSIONS: Anatomic knowledge of intrinsic and extrinsic brainstem structures, in association with a refined neurosurgical technique assisted by intraoperative monitoring, and surgical planning based on magnetic resonance imaging (MRI) and tractography have allowed for wide resection of brainstem lesions with low mortality and acceptable morbidity rates.

Brainstem abscess of undetermined origin: microsurgical drainage and brief antibiotic therapy.

CONTEXT: Solitary brainstem abscesses are rare and they are usually associated with other infections. They are severe conditions with high morbidity and mortality. The surgical options are stereotactic aspiration and microsurgical drainage. Systemic antibiotic therapy is used for more than six weeks. CASE REPORT: We present the case of a young man with a solitary abscess at the pons, without other systemic infections. The patient was treated by means of microsurgical drainage and antibiotic therapy for three weeks. His postoperative recovery was good. CONCLUSIONS: A microsurgical approach may be considered to be an important option for large abscesses that are multiloculated, close to the surface or contain thick fluid. Complete emptying of the purulent accumulation may diminish the required duration of antibiotic therapy.

Brainstem abscess of undetermined origin: microsurgical drainage and brief antibiotic therapy / Abscesso do tronco encefálico de origem indeterminada: drenagem microcirúrgica e antibioticoterapia curta

CONTEXT: Solitary brainstem abscesses are rare and they are usually associated with other infections. They are severe conditions with high morbidity and mortality. The surgical options are stereotactic aspiration and microsurgical drainage. Systemic antibiotic therapy is used for more than six weeks. CASE REPORT: We present the case of a young man with a solitary abscess at the pons, without other systemic infections. The patient was treated by means of microsurgical drainage and antibiotic therapy for three weeks. His postoperative recovery was good. CONCLUSIONS: A microsurgical approach may be considered to be an important option for large abscesses that are multiloculated, close to the surface or contain thick fluid. Complete emptying of the purulent accumulation may diminish the required duration of antibiotic therapy. .

CONTEXTO: Abscessos isolados do tronco encefálico são raros e geralmente associados a outras infecções. Trata-se de condição grave, com grande morbidade e mortalidade. Opções cirúrgicas são aspiração com estereotaxia e drenagem microcirúrgica. Antibioticoterapia sistêmica tem sido usada por mais de seis semanas. RELATO DE CASO: Apresentamos o caso de um jovem com abscesso pontino sem outras infecções sistêmicas. O paciente foi tratado com drenagem microcirúrgica e antibioticoterapia por três semanas. Houve boa evolução pós-operatória. CONCLUSÕES: Acesso microcirúrgico pode ser considerado uma opção importante no tratamento de grandes abscessos do tronco encefálico, que são multiloculados, próximos da superfície ou que contenham líquido espesso. Drenagem completa do material purulento pode diminuir o período de antibioticoterapia. .

Combined pre- and subtemporal transtentorial approach for epidermoid cysts of the cerebellopontine angle.

OBJECTIVE: Epidermoid cysts of the cerebellopontine angle (CPA) can be a surgical challenge for the pediatric neurosurgeon. Ideally, total removal must be achieved; however, occasional adhesions of these tumors to vital neurovascular structures and extension far beyond the midline may preclude their total removal. The aims of this article are to present an alternative surgical approach to these lesions and to provide the rationale for this technique. MATERIAL AND METHODS: A 16-year-old boy was admitted to our pediatric neurosurgery department with a 1-year history of nonspecific headaches. His neurological examination showed right-sided dysmetria and gait ataxia. Magnetic resonance scans showed a space-occupying lesion on the right CPA with low intensity on T(1)-weighted images and high intensity on T(2)-weighted images. RESULTS: Craniotomy for tumor excision via pre- and subtemporal transtentorial approach was performed disclosing a 3.5 × 3 × 2.8-cm(3) well-encapsulated tumor, which was confirmed to be an epidermoid cyst. The postoperative course was uneventful. CONCLUSIONS: A combined pre- and subtemporal approach utilizes a wide opening of the tentorium and the option of supratentorial retraction of the cerebellum to provide an excellent angle of approach to CPA lesions involving the anterolateral aspect of the brain stem in children.

Surgical management of brainstem cavernous malformations.

Bleeding from brainstem cavernomas may cause severe deficits due to the absence of non-eloquent nervous tissue and the presence of several ascending and descending white matter tracts and nerve nuclei. Surgical removal of these lesions presents a challenge to the most surgeons. The authors present their experience with the surgical treatment of 43 patients with brainstem cavernomas. Important aspects of microsurgical anatomy are reviewed. The surgical management, with special focus on new intraoperative technologies as well as controversies on indications and timing of surgery are presented. According to several published studies the outcome of brainstem cavernomas treated conservatively is poor. In our experience, surgical resection remains the treatment of choice if there was previous hemorrhage and the lesion reaches the surface of brainstem. These procedures should be performed by experienced neurosurgeons in referral centers employing all the currently available technology.

Cavernomas bulbares e ponto-bulbares: discussão sobre dois casos / Surgery of medullary and pontomedullary cavernomas: discussion on two cases

Os autores discutem a cirurgia de remoção de cavernomas bulbares e ponto-bulbares mostrando dois casos como exemplos. Estratégicas para essas operações e suas indicações são analisadas. Cavernomas bulbares e ponto-bulbares são possivelmente removíveis com baixo risco cirúrgico.

The authors discuss the surgery for the removal of medullary and pontomedullary cavernomas. Examples are showed. Strategic parameters are commented. Medullary and pontomedullary cavernomas may be elegible for surgical removal with low surgical risk.

Cavernomas pontinos extraventriculares. Parte I. Acesso transtentorial a cavernoma pontino dorsolateral / Extraventricular pontine cavernomas. Part I. Transtentorial route to remove a postero-lateral pontine cavernoma

Objetivo: Descrever a via transtentorial, por meio de craniotomia têmporo-occipital, para remoção de cavernoma pontino de localização dorsolateral, exemplificado pela apresentação de um caso. Conclusão: O acesso transtentorial demonstra-se útil e seguro para remoção de lesões localizadas nessa região da ponte.

Objective: To present the transtentorial route through a temporal-occipital craniotomy for surgical removal of a posterior-lateral pontine cavernomas, exemplified by the presentation of a case. Regional anatomy is discussed. Conclusion: The transtentorial approach may be used safely to remove lesions of highly located in the posterior-lateral region of the pons.

Cavernomas pontinos extraventriculares. Parte II. Acesso pré-sigmoideo transpetroso a cavernoma pontino ventrolateral / Extraventricular pontine cavernomas. Part II. Pre-sigmoid, transpetrosal approach to ventrolateral pontine cavernomas

Objetivo: Descrever a via pré-sigmoidea ampliada para acesso a lesões localizadas na região ventrolateral da ponte, exemplificado com a apresentação de um caso de cavernoma pontino nessa localização. Conclusão: Esse acesso, amplamente revisto pela literatura, é útil para remoção cirúrgica de cavernomas pontinos ventrolaterais.

Objective: To describe the pre-sigmoid transpetrosal approach to the ventrolateral pontine region, exemplified by the presentation of a case of cavernoma in this localization. Conclusion: This approach is useful to remove pontine ventrolateral cavernomas.

Endoscopic management of brainstem injury due to ventriculoperitoneal shunt placement.

INTRODUCTION: We report a patient who suffered from brainstem injury following ventriculoperitoneal (VP) shunt placement in the fourth ventricle. DISCUSSION: A 20-year-old man with complex hydrocephalus and trapped fourth ventricle underwent a suboccipital placement of a VP shunt. Postprocedure patient developed double vision. Magnetic resonance imaging showed that the catheter was penetrating the dorsal brainstem at the level of the pontomedullary junction. Patient was referred to our Neuroendoscopic Clinic. Physical exam demonstrated pure right VI cranial nerve palsy. Patient underwent flexible endoscopic exploration of the ventricular system. Some of the endoscopic findings were severe aqueductal stenosis and brainstem injury from the catheter. Aqueductoplasty, transaqueductal approach into the fourth ventricle, and endoscopic repositioning of the catheter were some of the procedures performed. Patient recovered full neurological function. The combination of endoscopic exploration and shunt is a good alternative for patients with complex hydrocephalus. A transaqueductal approach to the fourth ventricle with flexible scope is an alternative for fourth ventricle pathology.

Microsurgical anatomy of the safe entry zones on the anterolateral brainstem related to surgical approaches to cavernous malformations.

OBJECTIVE: To study the microanatomy of the brainstem related to the different safe entry zones used to approach intrinsic brainstem lesions. METHODS: Ten formalin-fixed and frozen brainstem specimens (20 sides) were analyzed. The white fiber dissection technique was used to study the intrinsic microsurgical anatomy as related to safe entry zones on the brainstem surface. Three anatomic landmarks on the anterolateral brainstem surface were selected: lateral mesencephalic sulcus, peritrigeminal area, and olivary body. Ten other specimens were used to study the axial sections of the inferior olivary nucleus. The clinical application of these anatomic nuances is presented. RESULTS: The lateral mesencephalic sulcus has a length of 7.4 to 13.3 mm (mean, 9.6 mm) and can be dissected safely in depths up to 4.9 to 11.7 mm (mean, 8.02 mm). In the peritrigeminal area, the distance of the fifth cranial nerve to the pyramidal tract is 3.1 to 5.7 mm (mean, 4.64 mm). The dissection may be performed 9.5 to 13.1 mm (mean, 11.2 mm) deeper, to the nucleus of the fifth cranial nerve. The inferior olivary nucleus provides safe access to lesions located up to 4.7 to 6.9 mm (mean, 5.52 mm) in the anterolateral aspect of the medulla. Clinical results confirm that these entry zones constitute surgical routes through which the brainstem may be safely approached. CONCLUSION: The white fiber dissection technique is a valuable tool for understanding the three-dimensional disposition of the anatomic structures. The lateral mesencephalic sulcus, the peritrigeminal area, and the inferior olivary nucleus provide surgical spaces and delineate the relatively safe alleys where the brainstem can be approached without injuring important neural structures.

[Deep-seated (corpus callosum, intraventricular, basal ganglia and insula) and brain stem cavernous angiomas. Experience in Brazil]. / Cavernomes profonds (corps calleux, intraventriculaires, ganglions de la base, insulaires) et du tronc cérébral. Expérience d'une série brésilienne.

With a review of the literature, we report our experience with surgical treatment of deep-seated cavernomas (intraventricular, of the corpus callosum, the capsula interna, the insula and the brain stem). Outcome was good in all nine patients after surgery for deep-seated brain cavernomas. There we also 13 cases of the brain stem cavernomas treated surgically. Of them, nine patients were stabilized or improved, one patient worsened, one patient died and two were lost to follow-up. Whatever the location, surgery should only concern symptomatic or hemorrhagic lesions close to the pia-matter or the ependyma as well as those covered by a thin layer of parenchyma. Neuronavigation and microsurgical procedures are essential in the treatment of deep-seated cavernomas.

Abordajes quirúrgicos al tronco encefálico. Parte 1: anatomía de superficie del tronco encefálico / Surgical approaches to brain stem. Part 1: anatomy surface of the brain stem

El tronco encefálico se ubica en la fosa posterior, en íntima relación con el cerebelo e importantes estructuras vasculares. Contiene en su interior tractos de sustancia blanca que vinculan entre sí cerebro, tronco encefálico, médula espinal y cerebelo. Contiene en su interior los núcleos de origen de los diez últimos pares craneanos y núcleos que regulan funciones, como la mirada lateral, la deglución o incluso el ciclo sueño - vigilia. Puede ser afectado por diversos tipos de patologías, como tumores, malformaciones vasculares, procesos infecciosos, inflamatorios o desmielinizantes. El presente es el primer artículo de cuatro, destinados a analizar los abordajes quirúrgicos más frecuentes al tronco encefálico. En esta primera parte se describen aquí los principales aspectos de la anatomía de superficie del tronco cerebral. (AU)

Abordajes quirúrgicos al tronco encefálico. Parte 1: anatomía de superficie del tronco encefálico / Surgical approaches to brain stem. Part 1: anatomy surface of the brain stem

El tronco encefálico se ubica en la fosa posterior, en íntima relación con el cerebelo e importantes estructuras vasculares. Contiene en su interior tractos de sustancia blanca que vinculan entre sí cerebro, tronco encefálico, médula espinal y cerebelo. Contiene en su interior los núcleos de origen de los diez últimos pares craneanos y núcleos que regulan funciones, como la mirada lateral, la deglución o incluso el ciclo sueño - vigilia. Puede ser afectado por diversos tipos de patologías, como tumores, malformaciones vasculares, procesos infecciosos, inflamatorios o desmielinizantes. El presente es el primer artículo de cuatro, destinados a analizar los abordajes quirúrgicos más frecuentes al tronco encefálico. En esta primera parte se describen aquí los principales aspectos de la anatomía de superficie del tronco cerebral. (AU)