Magnetic resonance imaging in differentiation between usual and unusual cerebellopontine angle lesions

To assess the role*of MRI in differentiation between usual and unusual cerebellopontine angle [CPA] lesions.The study was conducted on 40 patients with signs and symptoms pointing to CPA lesions and subjectedto MRI examination.MRI showed usual lesions such as Schwannoma in 14 patients and meningioma in eight patients. Lessfrequent lesions include glomus tumour in five patients and chordoma in five patients. Unusual lesions such asepidermoid cyst, arachnoid cyst, ependymoma, medulloblastoma, expophytic glioma, papillary adenocarcinoma ofendolymphatic sac, metastatic adenocarcinoma and atherosclerotic basilar artery in one patient for each entity.MRI could differentiate between usual and unusual lesions by proper identification of the site, extentand signal characteristic of each lesion

Bifurcation of the basilar artery and its relationship with the superior cerebellar artery at the proximal portion of the anterior pontine segment

The level of bifurcation of the basilar artery (BA) and its relationship with the initial course of the anterior pontine part of the superior cerebellar artery (SCA) was studied considering side, sex, ethnic group (EG) and horizontal cephalic index (HCI). The study was conducted in 70 brain from Brazilian adult cadavers of both sexes and from ethnic groups whose arteries were injected with neoprene latex. Cephalic measurements were taken for each individual according to MARTIN-SALLER's techniques. The BA presented higher bifurcation in the most of the cases in white and non-white, dolico-mesocephalic and brachy-hyperbrachycephalic group and in both sexes, and the SCA followed a superior course more frequently in the left side of these groups. The lower bifurcation of BA was observed in similar percentages in the white, non-white, dolicomesocephalic and brachy-hyperbrachycephalic groups. In females this bifurcation was more frequent than in males. The anatomic variability of these arteries has a tendency to be equal distributed among the studied variables.

Anatomia do ângulo pontocerebelar / Anatomy cerebellopontine angle

O ângulo pontocerebelar é a regiäo anterolateral da fossa posterior do crânio, constituindo um verdadeiro complexo neurovascular. A freqüência, relativamente alta, de processos patológicos nesta regiÒo justifica a importância neurocirúrgica da regiäo. No presente trabalho, realizou-se a dissecçäo de 11 ângulos pontocerebelares de cadáveres adultos formolizados, com o auxÝlio de lentes de aumento (3x) e injeçäo arterial de látex vermelho. Realizou-se o estudo das relaçöes anatômicas existentes entre o seus elementos, bem como a mensuraçäo dos diâmetros das estruturas vasculares, aliado à descriçäo de seus trajetos e origens, no interior da cisterna cerebelopontina. Os resultados obtidos foram compatíveis com os de outros autores.

Microanatomia do ângulo ponto-cerebelar com análise morfométrica do meato acústico interno / Microanatomy of the cerebellopontine angle with morphometric analysis of the internal acoustic meatus

Twelve cerebello-pontine angles of the corpses of six adults were dissected with the aid of a surgical microscope. The following parameters were analyzed: the superior-inferior (vertical) and the anterior-posterior (horizontal) dimensions of the internal acoustic meatus (IAM); and the distances from the IAM to the Meckel's cave, the superior jugular foramen (SJF) and the inferior jugular foramen (IJF). We used a mathematical formula to calculate the area of the IAM. Important variations in the IAM's measurements were found, mainly concerning its area. This study contributes to a better understanding of cerebello-pontine angle (CPA) structures and their relationships with osseous parameters in Brazilian individuals.

Partial sigmoid sinus release in translabyrinthine approach for cerebellopontine angle lesions

In this work, a modification of the routine translabyrinthine approach to cerebellopontine angle lesions is introduced. This modification is the partial release of the sigmoid sinus anteriorly and superiorly from its dural attachments. This allows retraction of the sinus posteriorly and inferiorly and consequently marked widening of the originally confined approach. 5 cases with large cerebellopontine angle tumors more than 4 cm in diameter were excised totally using this modification. Anatomical study on 10 fresh cadaveric specimens was carried out and showed that the modification increased the surface area of the window through which the surgeon operate by an average of 62%