Alberto Torres

The perforator-free zone of the posterior communicating artery and its relevance in approaches to the interpeduncular cistern, especially the transcavernous approach: an anatomic study.

OBJECTIVE Because the microsurgical working space in the interpeduncular fossa is very narrow, using different surgical approaches such as the pterional approach and/or the pretemporal transcavernous approach in combination with a division of the posterior communicating artery (PComm) at the longest perforator-free zone (PFZ) can help to enlarge the microscopic field of view and the working space in this area of the brain. METHODS In this microanatomic study, the variability of several parameters of the PComm, especially the location of the longest PFZ of the PComm, was examined and described in 23 cadaveric heads. RESULTS In most cases, the mean length of the longest PFZ was found to be between 2 and 6 mm. In 80% of the cases, the longest PFZ was located closer to the posterior cerebral artery than to the internal carotid artery. A total of 82.5% of all the PComms measured were of the adult type. In 55% of all arteries, a premamillary artery was identified. When a short and adult-type PComm obscures the microscopic view of the operative field, dividing the PComm is mandatory. In other situations, dividing the PComm is facultative. Because the PComm is usually predominantly irrigated by the internal carotid artery, it is of hemodynamic advantage that the longest PFZ is typically located closest to the posterior cerebral artery. CONCLUSION On the basis of this descriptive anatomic study, we conclude that when it is needed, division of an adult-type PComm at the longest PFZ is usually feasible and results in a low risk of compromising the blood flow to the branching perforators of the PComm.

Papillary tumor of the pineal region

Tumors of the central nervous system (CNS) demonstrating papillary features, and particularly in the pineal region, are rare. Papillary tumor of the pineal region (PTPR) is a recently described rare neuroepithelial tumour included in the fourth edition of the World Health Organization (WHO) classification of tumours of the CNS, published in 2007. This new histopathological entity manifests in children and adults, with magnetic resonance (MR) imaging showing variable degree of T1 hyperintensity signal as well as contrast enhancement. In addition to the initial report of six cases by Jouvet et al. (Am J Surg Pathol 27:505–512, 2003) several case reports have been published in the literature to date. PTPR is characterized by presenting an epithelial-like cytology and a papillary architecture with immunoreactivity for broad-spectrum cytokeratins. Ultrastructurally observed features suggest ependymal differentiation and a possible origin from specialized ependymal cells of the subcommissural organ (SCO) has been postulated. The differential diagnosis of PTPR include pineal parenchymal tumors, choroid plexus tumors, papillary ependymoma, papillary meningioma, and metastasis. As a result of the rarity of these tumors, the biological behaviour of PTPR is not yet clear. It may correspond to WHO grades II or III. The high risk of local recurrence makes accurate surgery followed by radiotherapy necessary to achieve optimal treatment.

Bilateral internal carotid artery aneurysm simulating pituitary apoplexy: case report.

OBJECTIVEIntracavernous internal carotid artery (ICA) aneurysms can extend into the sella and simulate pituitary adenomas. However, they are rarely associated with pituitary apoplexy. We present a rare case of bilateral intracavernous ICA aneurysms simulating a sellar mass with the clinical picture of a pituitary apoplexy. CLINICAL PRESENTATIONAn 82-year-old woman presented with a classic case of pituitary apoplexy with a history of headache, nausea, vomiting, and diplopia. She was found to have an intrasellar mass simulating a large and invasive pituitary adenoma. The patient had a medical history positive for breast cancer. INTERVENTIONBecause of the presentation with apoplexy and the possibility of metastatic breast cancer or pituitary adenoma, the patient was explored transsphenoidally to obtain pathological verification and possibly resect the tumor. Unusual intraoperative findings led to a microDoppler evaluation, suggesting a vascular lesion. Intraoperatively, an angiogram confirmed the presence of bilateral ICA giant aneurysms involving the ICA intracavernous component extending into the sella turcica. The patient refused further treatment. CONCLUSIONThe present case indicates that an intrasellar ICA aneurysm can be misdiagnosed as a macroadenoma and even present through pituitary apoplexy. When treating intrasellar masses with the slightest suspicion of a nonpituitary origin, further workup should be considered. The possibility of a vascular lesion simulating a pituitary adenoma should always be considered by neurosurgeons and ear, nose, and throat surgeons operating in the sellar region.

Resultados en el tratamiento quirúrgico de los neurinomas del acústico gigantes

INTRODUCTION AND OBJECTIVES To compare the results obtained in the resection of 21 giant vestibular schwannomas via retrosigmoid (RS) and combined retrosigmoid/translabyrinthine (RS/TL) approaches with respect to intra- and postoperative complications, facial nerve preservation and postsurgical sequelae. METHODS This was a retrospective study of 21 patients who underwent a resection of a giant vestibular neuroma according to the Tos & Thomsen Scale (greater than or equal to 4 centimetres) in a tertiary care centre in the period between 2000 and 2008. We present the most significant characteristics of the series studied and the analysis of the advantages and inconveniences of each approach. We also analyse the results regarding facial nerve function preservation. RESULTS We highlight the absence of mortality in the 21-patient group. There were no important intraoperative complications. Total resection of the lesion was achieved in the 87% of the cases, with facial nerve preservation of 73% using the combined RS/TL approach, in comparison to 40% using the RS. Facial nerve function after two years was acceptable or good in 67% (including those with heteronerve anastomosis). A global percentage of 14.3% of cerebrospinal liquid fistula was observed, as well as 9.5% of meningitis. CONCLUSIONS The results of the study demonstrate that the combined retrosigmoid translabyrinthine approach for giant schwannoma treatment offers increased facial nerve preservation and lower morbidity, constituting an important option in the treatment of this kind of tumours thanks to a multidisciplinary approach.

Contralateral hearing loss after vestibular schwannoma surgery : Case report

OBJECTIVETo describe a case of contralateral hearing loss (CHL) in vestibular schwannoma (VS) surgery and to discuss the factors potentially related with this complication. CLINICAL PRESENTATIONA 48-year-old man awakened with complete bilateral hearing loss after an uneventful retrosigmoid excision of a 20 mm left-sided VS. The patient had no complaints of vertigo or facial palsy on the contralateral side. The hearing loss proved to be endocochlear in origin and no improvement was observed after a 24-month follow-up period. DISCUSSIONCHL in VS surgery is not commonly reported but can occur frequently as a subclinical phenomenon if it is specially addressed. The cause is a compensatory endolymphatic hydrops generated by the loss of cerebrospinal fluid. In this circumstance, the hearing loss is usually reversible within 3 months, but irreversible cases have been described. Vascular damage to the cochlea can be another explanation in irreversible cases. The significance of other potential factors described in the literature as a cause of CHL in VS surgery is less clear. CONCLUSIONA case of CHL after VS surgery is presented. The hearing loss proved to be endochlear in origin and irreversible in nature. Irreversible damage to the cochlea resulting from loss of cerebrospinal fluid or vascular injury is probably related in this case reported.

Aneurysmal frontal bone cyst

A 66-year-old woman presented with a 2-month history of headache. Neurologic examination was normal and past history included colonic adenocarcinoma. MRI showed a cystic frontal bone lesion with heterogeneous contrast enhancement (figure, A, B). A preoperative diagnosis of brain metastasis with cranial invasion was made …

Original articleImportance of neoadjuvant chemotherapy in olfactory neuroblastoma treatment: Series report and literature reviewImportancia de la quimioterapia neoadyuvante en el tratamiento del neuroblastoma olfatorio: serie de casos y revisión de la literatura☆

Introduction and objectives Olfactory neuroblastoma (ONB) is a rare entity that constitutes less than 5% of nasosinusal malignancies. Mainstream treatment consists in surgical resection +/− adjuvant radiotherapy. By exposing results observed with apparition of new therapeutic options as neoadjuvant chemotherapy, the objective is to evaluate a series and a review of the current literature.INTRODUCTION AND OBJECTIVES Olfactory neuroblastoma (ONB) is a rare entity that constitutes less than 5% of nasosinusal malignancies. Mainstream treatment consists in surgical resection+/-adjuvant radiotherapy. By exposing results observed with apparition of new therapeutic options as neoadjuvant chemotherapy, the objective is to evaluate a series and a review of the current literature. METHODS A retrospective review was conducted including patients diagnosed and followed-up for ONB from 2008 to 2015 in our institution. RESULTS 9 patients were included. Mean follow-up of 52.5 months (range 10-107). Kadish stage: A, 1 patient (11.1%) treated with endoscopic surgery; B, 2 patients (22.2%) treated with endoscopic surgery (one of them received adjuvant radiotherapy); C, 6 patients (66.7%), 4 patients presented intracranial extension and were treated with neoadjuvant chemotherapy followed by surgery and radiotherapy. The other 2 patients presented isolated orbital extension, treated with radical surgery (endoscopic or craniofacial resection) plus radiotherapy. The 5-year disease free and overall survival observed was 88.9%. CONCLUSION Neoadjuvant chemotherapy could be an effective treatment for tumor reduction, improving surgical resection and reducing its complications.

20. Correlation between blink reflex (br) and corticobulbar motor evoked potentials (comeps) in skull base surgery and role as a predictor of clinical outcome

Introduction In 2009, Deletis et al. were the first to describe a method for eliciting the R1 component of BR in patients under general anaesthesia. The R1 includes trigeminal afferents, brainstem connections between trigeminal and facial nuclei and facial nerve. Therefore this technique might be considered a tool to intraoperatively monitor the involved structures in the reflex arc. In this work we compare the neurophysiologic behaviour of R1 component of BR and facial and/or trigeminal CoMEPs in 21 patients. Material and methods The study includes 21 patients diagnosed of skull base tumours that underwent surgery by the retrosigmoidal approach. Multimodal intraoperative monitoring was performed including: BR, lower facial and trigeminal CoMEPs, SEPs, MEPs and cranial nerve mapping. We used the published methodology by Deletis et al. to elicit BR and CoMEPs. Results Of the 21 patients, two patients with previous facial paresis did not have a BR. Of the 19 who had a BR; nine did not show changes in BR or CoMEPs during surgery. None of those had facial or trigeminal deficit postoperatively. Eight patients lost BR and presented significant decrement in amplitude of CoMEPs. Of these eight, five recovered all responses after stopping surgery momentarily, the other three didn’t recover responses and presented postoperative facial paresis. The last two patients lost BR during the surgery while CoMEPs didn’t show any change. We assumed that these changes in BR were due to changes in depth of anaesthesia. Conclusion There is a strong correlation between BR and CoMEPs changes during skull base surgery. BR and CoMEPs help to predict the clinical outcome of facial and trigeminal nerve function. BR should be included in the routine methodology for intraoperative monitoring skull base surgeries since is a reliable tool to monitor the structures involved in the reflex arc.

WO26 Multimodal intraoperative neurophysiological monitoring in intracranial aneurism surgery

this pilot study, we evaluate the potential applicability of this technique for cEEG monitoring in the ICU using 15 EEG recordings from ICU-patients who were monitored with cEEG for 24 to more than 80 hours. Results: Essentials of the raw EEG are well represented by the four proposed features. There is good agreement in the assessment of asymmetries, as may occur in focal seizures or unilateral ischaemia, and generalized background slowing. In addition, we illustrate its potential to detect abnormal increased synchronization, as present during focal or generalized epileptiform discharges. Conclusion: Visual transformation of the raw EEG assists in the interpretation and facilitates its use in the Intensive Care Unit

Current Management of Pineal Cysts

Primary intracranial tumors of the pineal region account for 0.5% of intracranial neoplasms. Most of these tumors are germ cell tumors, gliomas, and pineal parenchymal tumors. They usually grow as solid or infiltrative mass lesions. A cystic appearance is unusual; when it is seen, it often indicates a nonneoplastic pineal cyst. Unlike pineal tumors, pineal cysts are benign, usually are asymptomatic, and often are found incidentally on MRI. Since MRI became available, pineal cysts have been detected in healthy subjects at a rate of 1.4 ± 4.3%, and they are found incidentally in approximately 40% of routine autopsies (Fig. 1). They can occur in patients of any age, from the fetal period to old age, with predominance in women in the third and fourth decade of life. These lesions are believed to be benign, but their natural history is unknown. They are thought to occur as a result of normal involution of the gland, and a congenital dysembryonic origin secondary to incomplete obliteration of the cavum pineale has been proposed. Other hypotheses include degeneration and secondary cyst formation, ependymal invasion of glial lacunae, invagination of the pineal gland, and a normal anatomic variant. One might speculate that a pineal cyst in a very young person has a dysembryogenetic origin whereas one in an elderly person would be more likely to have a degenerative etiology. Pathologic Characteristics Histologically, these lesions are true nonneoplastic cysts with a characteristic appearance. The cyst wall is composed of three layers: an inner gliotic layer with a high number of Rosenthal fibers; a middle layer with columns of pineal parenchyma; and a thin fibrous external layer (Fig. 2). Sometimes, these cysts can be misdiagnosed as pineocytomas if the pathology specimen includes primarily the parenchyma surrounding the cyst. Rosenthal fibers, granular bodies, and hyalinized vessels are features that usually are characteristic of pilocytic astrocytoma but may be present in pineal cysts. Features that help distinguish a pineal cyst from a pilocytic astrocytoma include the thin-walled nature of the specimen, the layered architecture, the lack of microcyst formation, and the relative hypocellularity. Macroscopic observation of the cyst is important, especially in regard to the appearance and color of the fluid contents. In benign lesions, the fluid often is clear, whereas in astrocytomas, the liquid is brown.