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Post-traumatic haematomas in the posterior fossa are uncommon, with a reported incidence of 3%, and occur along the cerebellar convexity [1]. Retroclival location is uncommon and retroclival haematomas are mostly epidural. Only 6 cases of post-traumatic retroclival subdural haematomas (RCSDH) are reported in literature [2]. These are associated with significant trauma and occur in the young. Four cases of spontaneous RCSDH have also been described, three patients with coagulation disorders and one patient with pituitary apoplexy [2]. All six of the reported post traumatic RCSDH were patients aged below 20 years while the non-traumatic RCSDH were older patients. Out of the six post traumatic RCSDH, five have been managed conservatively while one required surgery due to emergence of neurological symptoms. Due to their strategic location and rarity, retroclival haematomas pose a challenge in diagnosis and management [3].

Background In recent years, transorbital endoscopic approaches are increasing in popularity as they provide several corridors to reach lateral areas of the ventral skull base through the orbit. The aim of this study is to investigate the feasibility of the inferolateral transorbital endoscopic approach (ILTEA) by detailing the step-by-step dissection, anatomic landmarks, and target anatomic areas. Methods Seven cadaveric specimens (14 sides) were dissected in the Laboratory of Endoscopic Anatomy of the University of Brescia. Step-by-step dissection of ILTEA was performed to identify the main anatomic landmarks and corridors. Skin incision, dural incision, and boundaries of craniectomy were measured. Neuronavigation was used to check landmarks, track boundaries of surgical volumes, and measure orbital dislocation. Results The study on the 14 ILTEAs defined 1 anatomic area ("waterline door") that leads to 4 corridors: Meckel's cave corridor, carotid foramen corridor, petrous corridor, and transdural middle fossa corridor. Crucial anatomic landmarks were identified and analyzed. Orbital dislocation was Conclusions ILTEA provides the surgeon with a direct route to the region of the "waterline door," lateral areas of the ventral skull base, and middle cranial fossa. In addition, it allows an optimal view of the intracranial and extracranial portions of the maxillary and mandibular nerves. Further anatomic and clinical studies are needed to validate ILTEA in surgical practice.

A 12-year-old boy was referred by his orthodontist due to the dysmorphic condition of the impacted teeth 18 and 28. Because teeth 17 and 27 were close related to the third molars, the decision was made to remove the impacted teeth under general anaesthesia. During luxation of tooth 28, it was accidentally displaced deeper into the socket. The tooth could still not be localized after the use of radiographs, an antrostomy, and surgical exploration. It was decided to leave the 28 in its place and to perform cone beam computertomography. This showed that tooth 28 was displaced into the infratemporal fossa. Since the patient was free of symptoms, a period of watchful waiting was initiated. A control visit and cone beam computertomography 9 months postoperatively revealed no signs or symptoms or changes in the position of the displaced tooth. It was therefore decided to leave the third molar in its displaced position. Displacement of a maxillary third molar into the infratemporal fossa is considered a rare complication.

Resumen Objetivos Conocer por medio de una encuesta la actuacion de los anestesiologos espanoles en el manejo perioperatorio de los pacientes intervenidos neuroquirurgicamente de enfermedades de fosa posterior del craneo. Material y metodos Se remitio a los servicios de anestesiologia de hospitales con servicio de neurocirugia un cuestionario con un planteamiento cerrado sobre la participacion de los anestesiologos en el tratamiento perioperatorio de los pacientes sometidos a cirugia de fosa posterior. Resultados De los 73 hospitales nacionales publicos que disponen de servicio de neurocirugia, completaron el formulario 42 (57,5%). En 36 centros se realiza la cirugia de fosa posterior con el paciente en sedestacion, aunque se emplea con menor frecuencia que el decubito lateral o el decubito prono. La monitorizacion neurologica especifica es escasa, asi como el empleo del Doppler precordial y/o transcraneal para la deteccion de embolia vascular aerea. La tecnica anestesica mas empleada en estos procedimientos es la intravenosa. En menos del 10% de los centros se emplea oxido nitroso, y en un 15% se evitan los bloqueadores neuromusculares cuando se usa monitorizacion neurofisiologica intraoperatoria. Los problemas cardiovasculares durante la cirugia se refieren como muy frecuentes en el 29% de los centros, mientras que en el postoperatorio las complicaciones referidas como mas habituales son los deficit de pares craneales, el edema de via aerea (23%) y los vomitos postoperatorios (47%). Conclusiones Los resultados obtenidos de la encuesta muestran que en las cirugias de fosa posterior la sedestacion se utiliza menos que el decubito prono y que apenas se usa monitorizacion neurofisiologica intraoperatoria.

WOS: 000418306600012 PubMed: 28926835 …

Object The purpose of this study was to report the results of a survey of the American Society of Pediatric Neurosurgeons (ASPN) on treatment of Chiari malformation Type I (CM-I) with syringomyelia. Methods A questionnaire was circulated during the 2006 meeting of the ASPN, in which surgeons were surveyed on their management of patients with CM-I and syringomyelia. The survey consisted of questions about 4 clinical scenarios, common causes of surgical failures, and complications. Results There were 72 respondents, representing more than 90% of attendees at the 2006 ASPN meeting and approximately half of the society's members. The majority of respondents (85%) reported that they perform posterior fossa decompression as first-line treatment for CM-I with syringomyelia. Seven percent perform bony decompression alone, 36% open the dura, and 27% shrink the tonsils. Very few respondents indicated that they offer syrinx drainage as first-line therapy (< 3%). Although all respondents reported that they treat symptomatic CM-I/syringomyelia patients surgically, 15% of respondents indicated that they do not operate on asymptomatic patients. Finally, respondents stated that their most common complications are pseudomeningocele and chemical meningitis. Conclusions This survey, given to a representative group of experienced North American pediatric neurosurgeons, confirms that posterior fossa decompression is still the preferred treatment modality in children with CM-I and syringomyelia, regardless of symptoms. Although most surgeons open the dura, preferred techniques for decompression vary. In contrast to the results of past surveys, conservative follow-up is now only used by a minority of respondents and only in the asymptomatic patient, and primary syrinx drainage seems to have lost popularity. A multicenter trial of surgical outcomes has been designed based on the information from this survey.

The clivus is one of the most central parts of the skull base. As diseases of the clivus evade clinical evaluation imaging plays a pivotal role in establishing a diagnosis. This article combines the description of anatomy and pathology with an extensive pictorial essay. Starting with the development and normal macroscopic anatomy of the clivus the reader is then introduced to a large variety of normal variations and developmental disorders some of them with clinical significance. Typical examples of non-neoplastic and neoplastic masses of the clivus and their differential diagnoses are provided. The article concludes with a review of inflammatory disease and trauma.

Made available in DSpace on 2013-08-12T18:42:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-01 Made available in DSpace on 2013-09-30T18:29:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:43:04Z No. of bitstreams: 0 Made available in DSpace on 2014-05-20T13:43:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-01-01 The caroticoclinoid foramen is an inconstant structure, formed by the union of the anterior and middle clinoid processes. The aim of this study was to perform an incidence and morphometry of the caroticoclinoid foramen in Brazilian human skulls and discuss its clinical implications. Eighty dry human skulls with sex distinction were used, and 3 groups of incidence were determined: General, sex, and sides. The morphometry was performed using a manual caliper and the major diameter of the foramina was measured; the values were also divided in general, according to sex and sides. The incidence of skulls with at least one foramen was 8.5%. According to the sides, 8.5% of the skulls showed foramen on the right side and 2.5% on the left. We found 2.5% of the skulls with bilateral foramen and 6.25% with unilateral foramen. In relation to sex, the foramens were found in 5% of male skulls and 12.5% of female skulls. The major diameter of this structure presented on mean, values of 5.23 mm on general, 5.18 mm on the right side and 5.35 mm on the left, 5.30 mm in male skulls and 5.18 mm in female skulls. The anatomical characteristics of this foramen should be considered in view of its clinical implications associated with neurosurgery as clinoid process removal, and symptoms as headache due to internal carotid artery alterations in this region. In conclusion knowledge of this structure supports the diagnosis and treatment of clinical complications related to this variation. Univ Estadual Campinas, State Univ Campinas, Dept Morphol, Anat Area, BR-13414903 Piracicaba, SP, Brazil Univ Estadual Campinas, State Univ Campinas, Dept Physiol Sci, Pharmacol Anesthesiol Therapeut Area, São Paulo, Brazil Univ Estadual Paulista, Paulista State Univ, Anat Area, Dept Basic Sci, São Paulo, Brazil Univ Estadual Paulista, Paulista State Univ, Anat Area, Dept Basic Sci, São Paulo, Brazil

Background The aim of this study was to describe and correlate radiographically the anterior ethmoidal artery (AEA) to useful endoscopic surgical landmarks, such as the nasal beak (NB), nasal crest (NC), and axilla of the middle turbinate, because these are commonly encountered during endoscopic sinus surgery and skull base surgery. Methods A retrospective review and software analysis was performed by three independent observers. Measurements of distance and angulation from the AEA to the NC, NB, and axilla of the middle turbinate were performed. A total of 138 unique computed tomography (CT) scans performed at a university tertiary care center were evaluated. Results The average age of the patients whose scans were analyzed was 50.5 (range, 17–90 years) years of age. The gender distribution was 61 male and 89 female patients. After comparing the measurements to the three landmarks noted, it was determined that the NB had the most interpatient concordance and the least interobserver variability. The average distance between the NB and the AEA as it penetrates the lamina papyracea is 2.34 cm (variance, 0.07) at an angle of 45.21° from the Frankfurt horizontal line. Conclusion The real advantage of this novel use of the NB as a landmark to identify the AEA is that it is easy to use, unobtrusive, and is not time-consuming. This relationship between the NB and the AEA is consistent across genders and ethnicities and is more valuable than others presented previously, which may be more variable.

OBJECTIVES: To assess if the volumes of the caudal cranial fossa (CCF), parenchyma within the caudal cranial fossa (CCFP) or ventricles (V) are associated with syringomyelia (SM) in cavalier King Charles spaniels (CKCS) with Chiari-like malformation (CM). To evaluate if volumes are associated with transverse syrinx width. METHODS: Magnetic resonance images of 59 CKCS with CM were retrospectively reviewed and grouped with or without SM. Three-dimensional images were created and volumes of the fossae, brain parenchyma and ventricular system were calculated from which percentages of CCF, CCFP and V were created. If present, syrinx size was measured from its maximal transverse width. The percentages were statistically compared between groups, and correlation between percentages and syrinx dimensions was made. RESULTS: CKCS with SM had significantly higher CCFP (P=0.0001) and V (P=0.0002) to those without but no significant difference in CCF (P=0.925). There was a positive correlation between CCFP and syrinx width (Pearson r=0.437) and ventricle size to syrinx width (Spearman r=0.627). CLINICAL SIGNIFICANCE: A more marked overcrowding of the CCF is associated with SM, which may explain the high incidence of SM in CKCS with CM. The association between ventricle and syrinx dimensions supports the theory that SM development is the result of altered cerebrospinal fluid dynamics.

There is scant and conflicting literature regarding bony canals of the clivus. To date, only osteological observations of dry skulls have been made of such structures and multiple hypotheses exist regarding the etiology of these entities and whether or not they represent normal variations or pathology. The present study was performed to elucidate, specifically, clival canals of the occipital portion of the clivus.One hundred dry skulls (80 adult and 20 children) and 47 adult cadavers were included, and the superior and inferior surfaces of their clivus were inspected for bony defects/canals. When identified, the canals were measured and their potential contents removed. The contents of the canals in these cadaveric specimens were submitted for histological analysis.A canal of the clivus was identified in 5% of dry specimens and in 6.4% of cadaveric specimens. One diagonal and five more or less vertical canals were found. One canal was observed to have a single opening and one canal was found to have three openings. For the cadaveric canals, histology of the contents revealed no pituitary or notochordal tissue with only vascular anatomy consistent with veins. These venous structures appeared to connect parts of the basilar venous plexus.Based on our study, which is the first of its kind, such canals of the occipital portion of the clivus should not be mistaken for pathology and represent simple vascular channels.

Background Chordomas are primarily malignant tumors encountered at either end of the neural axis; the craniovertebral junction and the sacrococcygeal junction. In this article, we discuss the surgical management of craniovertebral junction chordomas. Objective In this paper, we discuss the surgical management of craniovertebral junction chordomas. Results The following approaches are illustrated: transoral-transpalatopharyngeal approach, high anterior cervical retropharyngeal approach, endoscopic transoral approach, and endoscopic transnasal approach. No single operative approach can be used for all craniovertebral chordomas. Therefore, the location of the tumor dictates which approach or approaches should be used.

Objective The indications and operative technique for a number of posterolateral approaches to the craniovertebral junction (CVJ) are reviewed. Methods The literature addressing posterolateral approaches to the CVJ is reviewed, and illustrative cases are presented. Results The far lateral approach and its variants, including the transcondylar, supracondylar, and paracondylar approaches, are an effective means of addressing intradural anterior and anterolateral CVJ lesions. These approaches provide exposure of the lower third of the clivus, the foramen magnum, and the upper cervical spine; do not cross contaminated regions; and enable a watertight dural closure to be performed. They are associated with minimal morbidity and usually do not significantly decrease the stability of the CVJ. Conclusion All surgeons treating lesions of the CVJ should be familiar with the posterolateral approach and its modifications.

Gliosarcoma (GS), known as variant of glioblastoma multiforme, is aggressive and very rare primary central nervous system malignant neoplasm. They are usually located in the supratentorial area with possible direct dural invasion or only reactive dural thickening. However, in this case, GS was located in lateral side of left posterior cranial fossa. A 78-year-old man was admitted to our hospital with 3 month history of continuous dizziness and gait disturbance without past medical history. A gadolinium-enhanced MRI demonstrated 5.6×4.8×3.2 cm sized mass lesion in left posterior cranial fossa, heterogeneously enhanced. The patient underwent left retrosigmoid craniotomy with navigation system. The tumor was combined with 2 components, whitish firm mass and gray colored soft & suckable mass. On pathologic report, the final diagnosis was GS of WHO grade IV. In spite of successful gross total resection of tumor, we were no longer able to treat because of the patient's rejection of adjuvant treatment. The patient survived for nine months without receiving any special treatment from the hospital.

Occipital growth depends on coordinated deposition and resorption on the external and internal surface and includes interrelated processes of movement: cortical drift, displacement, and relocation. The current work aspires to map patterns of remodeling activity on the endocranial surface of the occipital bone from childhood to adulthood using a larger study sample compared with previous studies. The study sample consists of 5 adult and 10 immature (2(1/4) to 8 years old) occipital bones from skeletal remains from the eighteenth and nineteenth century. Preparation of the samples includes the elaboration of negative impressions, positive replicas coated with gold, and observed with the reflected light microscope. Cerebellar fossae are typically resorptive in both immature and adult specimens. Cerebral fossae, on the other hand, exhibit a resorptive surface in early childhood and turn into depository around the age of 7 years, which places this transition within the age interval of the completion of cerebral development. Depository fields are also observed in adult cerebral fossae. The remodeling map presented here is consistent with the results of Mowbray (Anat Rec B New Anat 2005;283B:14-22) and differs from cellular patterns described by Enlow. Future research implicating more elements of the neurocapsule can shed light on the factors affecting and driving occipital growth.

Arguments are given to plead why micro-vascular decompression should be the first surgical option to treat primary trigeminal neuralgias resistant to anticonvulsants.

Our aim was to determine whether the anatomical configuration of the posterior fossa and its substructures might represent a predisposition factor for the occurrence of clinical neurovascular conflict in trigeminal neuralgia (TN).We used MRI volumetry in 18 patients with TN and 15 controls. The volume of the pontomesencephalic cistern, Meckel's cave and the trigeminal nerve on the clinical and non-affected sides was compared. The reliability has been assessed in all measurements.The posterior fossa volume was not different in the clinical and control groups; there was no difference between the affected and non-affected sides when measuring the pontomesencephalic cistern and Meckel's cave volume either. The volume of the clinically affected trigeminal nerve was significantly reduced, but with a higher error of measurement.We did not find any association between the clinical neurovascular conflict (NVC) and the size of the posterior fossa and its substructures. MRI volumetry may show the atrophy of the affected trigeminal nerve in clinical NVC.

Objective—To perform morphometric analysis of the caudal cranial fossa in Cavalier King Charles Spaniels (CKCSs), to assess the relationship between caudal fossa dimensions and the frequency of magnetic resonance imaging (MRI) features of occipital abnormalities in CKCSs (with and without syringomyelia), and to compare caudal cranial fossa measurements in CKCSs with measurements of 2 groups of mesaticephalic dogs. Animals—70 CKCSs and 80 mesaticephalic (control) dogs. Procedures—Dogs were placed into 4 groups as follows: Labrador Retrievers (n = 40), spaniel-type dogs (40; English Springer Spaniels and Cocker Spaniels), CKCSs with syringomyelia (55), and CKCSs without syringomyelia (15). Multiple morphometric measurements (linear, angular, and area) were obtained from cranial midsagittalT2-weighted magnetic resonance images including the brain and cervical portion of the spinal cord. Several specific MRI findings were also recorded for CKCSs that appeared to affect the occipital bone and cervicomedullary junction. Results—No significant difference was identified among breeds in control groups and between sexes in any of the groups for all morphometric measurements. Significant differences were identified in CKCSs, compared with mesaticephalic dogs, in the area of the caudal cranial fossa and for several linear measurements that reflected the length of the ventral aspect of the occipital bone. These differences were greater in CKCSs with syringomyelia. All CKCSs had abnormalities in occipital bone shape. Conclusions and Clinical Relevance—CKCSs had a shallower caudal cranial fossa and abnormalities of the occipital bone, compared with those of mesaticephalic dogs. These changes were more severe in CKCSs with syringomyelia.

Facial nerve schwannomas are uncommon benign tumours and seldom extend into the middle cranial fossa. This is a case report of a giant facial nerve schwannoma extending from the middle cranial fossa to the mastoid region, which was successfully removed using combined interdisciplinary subtemporal and transmastoid approaches. Complete resection of the tumour was the optimal therapy for this patient because the facial nerve had been severely destroyed by the tumour. The clinical presentation, histological features, radiological findings and management of this case, as well as the relevant literature, are presented.

In this study, we explored the operation options for middle cranial fossa arachnoid cysts (MCFAC). One hundred and forty-nine patients who were operated for a symptomatic MCFAC between 1993 and 2006 in our hosptial were analyzed. Follow-up time ranged from 1 y to 14 y (mean=5.4 y). All these patients were divided into three subgroups according to Galassi classification. Long-term outcome and complications were studied respectively. Fenestration (F) resulted in a more favorable long-term outcome and less complication for cysts of types I and II, whereas a favorable outcome was noted in type III patients who underwent cysto-peritoneal shunting (S). We are led to conclude that Fenestration is suitable for cysts of types I and II (Galassi classification), cysto-peritoneal shunting is better for cysts of type III.

Petroclival meningiomas are vaguely defined as tumours arising from the antero-medial zone to the internal auditory meatus. This report subclassifies petroclival meningiomas based on their origin determined by using radiological and intra-operative findings.Ninety-one patients with petroclival meningioma underwent surgery via the anterior transpetrosal approach. The Meckel's cave was routinely opened. Tumour origin was classified into four subtypes according to the main attachment and trigeminal nerve deviation into, upper clivus (UC), cavernous sinus (CS), tentorium (TE), and petrous apex (PA). Their characteristic clinical symptoms and anatomical features were investigated.The characteristic symptom was ataxia in the UC type (37.5%), abducens nerve palsy in the CS type (64.3%) and trigeminal neuropathy, mainly neuralgia in the PA type (80.0%) with a higher statistical difference from other subtypes. The rate of tumour invasion into Meckel's cave reached 70.3% in average, with the lowest rate in the PA type (25.0%). The rate of middle fossa extension was the highest in the TE type (59.5%). The middle fossa approach was considered to be ideal for UC and TE types because of easier access to the Meckel's cave. Radical dissection without complications was difficult in the CS type. Both the anterior transpetrosal approach and the lateral suboccipital approach could be indicated in the PA type due to the rare invasion of Meckel's cave and middle fossa, and frequent extension into the internal auditory meatus.This classification is useful to predict the relation between the tumour and the cranial nerves based on symptoms and images. The anterior transpetrosal approach could be used for all four subtypes and with an absolute indication in the UC and TE types showing middle fossa extension.

Intraoperative 3D-navigation at the anterior skull base has become a very valuable tool in the last years. For a successful use the clinical pathways need a slight adaptation only to provide the radiologic imagery to the system. Established algorithms and standardized protocols have proven 3D-navigation systems as a valuable clinical tool, when used in conjunction with appropriate intraoperative quality assurance. Ease-of-use and reliable intraoperative quality assurance is an active area of research that, combined with adequate strategies for referencing the patient to preoperative high-resolution radiologic data, will make 3D-navigation at the lateral skull base a successful clinical tool as well.

INTRODUCTION Otogenic intracranial complications are rare. Misdiagnosed and untreated can be dangerous for health and life. They should be always kept in mind. AIM We discuss patients in whom defects of skull base were observed during operation. These defects can lead to serious intracranial complications. MATERIAL AND METHODS We analyse patients with chronic otitis media operated in our department between 2004-2006. 250 operations on ears were performed in that period of time. We discuss patients with intracranial otogenic complications and patients in whom defects of skull base were noticed by chance during operations. RESULTS Defects of skull base were observed in 24 cases. Intracranial complications were in 3 patients. 1 patiens died because of abscess of cerebellum, others were treated with good distant effect. Used methods of reconstruction were effective, we observed no discharge of cerebro-spinal fluid and no other intracranial complications. CONCLUSIONS It exists group of patients with chronic otitis media that have asymptomastic defects of cranial fossa. These defects can be responsible for intracranial complications. MRI and TC are very important in preoperative diagnostics.

Background: Arachnoid cysts are intra-arachnoidal cerebrospinal fluid collections most frequently seen in the middle cranial fossa. The optimal method of treatment for symptomatic arachnoid cysts remains controversial and includes cyst shunting, open craniotomy and endoscopic fenestration. All these techniques, however, have been associated with the development of postoperative subdural fluid collections. We describe a new endoscopic transcortical technique that attempts to avoid this complication. Methods: Six patients with middle cranial fossa arachnoid cysts were treated with endoscopic fenestration at our institution between January 2002 and December 2005. Three cases were approached directly through the cyst, while the other 3 were approached by passing the endoscope through the rim of adjacent cortex. Results: All six endoscopic fenestrations were successful in treating the arachnoid cysts. Among the 3 patients treated via a direct cyst entry, 2 cases developed significant subdural hygromas, 1 of which required aspiration. On the other hand, 1 of the 3 cases treated using a transcortical technique developed an insignificant postoperative extra-axial collection that resolved at 3 months without intervention. Conclusion: Endoscopic fenestration is an effective treatment for symptomatic arachnoid cysts. Endoscopic fenestration via a transcortical approach attempts to minimize cerebrospinal fluid drainage into the subdural space, avoiding the development of significant postoperative extra-axial collections, while promoting flow into the basal cisterns.

This study aimed to assess changes in the posterior cranial fossa (PCF) to shed light on the mechanism of cerebellar herniation in children with Costello syndrome (CS) and posterior fossa crowding. We performed a morphovolumetric PCF analysis on brain magnetic resonance imaging (MRI) in seven children with CS (mean age 31 ± 16 months) comparing the MRI scans with those of seven age-matched healthy subjects. PCF volume (PCFV), PCF brain volume (PCFBV) and cerebellar volume (CeV) were assessed on axial T2-weighted MRI. Morphometric parameters (diameters of the foramen magnum, tentorial angle, basiocciput, supraocciput, basisphenoid and exocciput lengths) were measured on sagittal T1-weighted MRI. The volume of the cerebrospinal fluid (CSF) spaces was calculated as PCFV minus PCFBV. Five out of seven CS children showed tonsillar herniation in the upper cervical canal; no child had hydrocephalus but three out of seven children showed ventriculomegaly. In addition, the PCFV/PCFBV ratio, PCFV, CSF spaces volume, basiocciput, basisphenoid and exocciput lengths and latero-lateral and antero-posterior diameters of the foramen magnum were significantly reduced, whereas no significant changes were found in supraocciput length, PCFBV, CeV or hindbrain volume The volumetric reduction of the PCF due to bony posterior fossa hypoplasia is a predisposing factor for developing cerebellar tonsillar herniation through the foramen magnum in children with CS. The altered anatomy of the foramen magnum and upward expansion of the PCF secondary to an increased tentorial slope serves to explain the possible mechanism of cerebellar herniation in patients with CS.

Abnormalities of the craniovertebral junction (CVJ) are highly prevalent in Northeast of Brazil, where it is linked to braquicefalic biotype, also common in this region. The ectopic tonsils are the main anatomopathological feature of the type 1 Chiari Malformation (CM 1) and derived from a small posterior fossa. The best way to treat the CM 1 is one of the most controversial topics in the neurosurgical field. The present study evaluated the two most applied techniques to treat CM 1, by means of clinical and radiological parameters. Methods: A total of 32 patients were evaluated. They were divided in two groups: Group 1 had 16 patients that were submitted to cranio-dural decompression of the CVJ; Group 2 also had 16 patients and in addition to cranio-dural decompression of the CVJ, they also had intra-arachnoid manipulation, including tonsils reductions. These groups were analyzed and compared in terms of neurological exam and cerebrospinal fluid flow imaging by using phase-contrast magnetic resonance technique, in two different times: pre and postoperative periods. Results: Both techniques were equivalents in terms of neurological improvement of the patients (p>0,05), but the Group 2 had more surgical complications, with relative risk for this kind of event, of 2,5. Whatever the cerebrospinal fluid flow at CVJ, the patients of the Group 1 achieved greater amount of flow than the Group 2 (p

Background:Misdiagnosis of spontaneous intracranial hypotension remains a problem, despite increasing recognition.Methods:Three patients with spontaneous intracranial hypotension presented with typical findings on lumbar puncture, magnetic resonance (MR) imaging, and radioisotope cisternography. All patients showed subdural effusions in the posterior fossa on axial T2-weighted MR imaging. Axial MR images of 112 patients with other conditions were also screened for this finding.Results:One of three patients had typical orthostatic headache, and the other two had continuous headache. The finding of subdural effusions in the posterior fossa on axial T2-weighted MR imaging disappeared after treatment. Similar findings were found in 14 of 112 patients with other conditions. Most of the patients were over 60 years old or had dementia or previous radiation therapy.Conclusion:Subdural effusions in the posterior fossa can be identified by T2-weighted axial MR imaging, and are useful for the diagnosis of spontaneous intracranial hypotension and for verifying the effectiveness of treatment.

Evidence of a high jugular bulb position (HJBP) during the translabyrinthine approach may compromise the surgical removal of cerebellopontine angle (CPA) tumours. We report a simple surgical procedure to safely manage this frequent normal variation and comment on various alternative options.The translabyrinthine approach included a complete skeletonization of the sigmoid sinus and of the presigmoid dura. A thin eggshell bone was left at the jugular bulb surface. The dome of the jugular bulb was gently dissected from the jugular fossa and gradually retracted downward in a tailored way, allowing the surgeon to drill below the internal auditory meatus. A small piece of bone was wedged over the jugular dome in order to maintain its lowered position.Among 178 consecutive translabyrinthine approaches performed for the removal of large CPA tumors, the use of this procedure was required in 44 cases of HJBP. Excepting minimal venous bleeding easily controlled in several cases, we never observed any complication from this procedure nor failure to expose the inferior compartment of the CPA.The HJBP can be systematically diagnosed with the preoperative CT-scan using bone window imaging. Our results demonstrate that the described procedure is safe and effective to widen the operative corridor that is required for the exposure of the inferior compartment of the CPA in this anatomical situation.

We present a case report of a giant cell tumor located in the skull base orginating from clivus and sphenoid bone treated by surgery and external beam radiotherapy (EBRT).

The purpose of this article is to provide insight into the development of surgery for acoustic neurinomas throughout the years. The significant contribution of surgical authorities such as Cushing, Dandy, and House are discussed. The advances in surgical techniques from the very first operations for acoustic tumors at the end of the 19th century until today are described, with special emphasis on the technological and diagnostic milestones that preceded each step of this development.

This article focuses on selected key anatomic considerations in anterior skull base surgery, briefly reviews common pathologies of the paranasal sinuses, and provides an overview of surgical approaches, complications, and results.

Anterior craniofacial resection has become a standard procedure for management of lesions of the anterior skull base. During the last 2 decades, modifications of the classic anterior craniofacial resection have been reported. With the introduction of endoscopic sinus techniques and instrumentation, surgeons have begun to use endoscopic approaches for management of anterior skull base lesions. This article describes endoscopic modifications of anterior craniofacial resection.

Objective The preservation of the olfactory tract during bifrontal approach for lesions located in the frontal skull base and the supra- and parasellar region has not previously been investigated. Methods In our study 12 patients underwent surgery for various lesions via the basal subfrontal route. All patients were observed prospectively, olfaction testing was performed pre- and postoperatively by an independent otorhinolaryngologist. Results We obtained complete preservation of the olfactory tracts and normal postoperative olfaction in all 12 cases. Conclusion The bifrontal approach allowed a bilateral, wide operative field with excellent orientation and views of important structures. The shortcoming of this method, damage of the olfactory tracts and postoperative anosmia can be overcome.

For surgeons operating in the standing position, the manipulation of foot switches involves shifting of the weight to the pivoting leg and the possible loss of contact between the switch and the foot. We solved this problem by changing the position of the switch that operates bipolar forceps. Our novel device is made of aluminum plates. The base plate features a foot strap and a height-adjustable overhang over the switch-operating foot. A commercially-available disc type foot switch is attached to the underside of the overhang in upside-down position, so the switch is operable with the toe. To turn on the switch, the toe is flexed dorsally to push the switch pedal, so the action is limited to the part distal to the metatarsophalangeal joints. Our switch was used in more than 100 consecutive microsurgeries performed by surgeons operating in the standing position. The switch manipulation required no shifting of the weight and was easier and quicker than manipulation of conventionally-placed switches. The surgeons were able to change the foot position freely with the modified switch, thereby avoiding loss of contact with the switch. The modified switch placement reduced physical fatigue in the lower extremities, annoyance related to the manipulation of conventionally-placed switches, and increased the comfort of surgeons operating in the standing position.

Two patients with a posterior fossa arachnoid cyst responsible for isolated facial nerve palsy are reported.The relationships between the cyst and the facial nerve and between the facial nerve palsy and the size variation of the cyst are discussed and documented by pre- and postoperative magnetic resonance imaging.

The prerequisite for the correct diagnosis and accurate delineation of skull base lesions is familiarity with the complex anatomy of the skull base. Imaging plays a central role in the management of skull base disease because this region is often difficult to evaluate clinically. CT and MR imaging are complementary; they are often used together to demonstrate the full disease extent. This article focuses on the critical anatomy of the skull base and how this knowledge contributes to accurate disease assessment.