The aim of this study was to assess the usefulness of proton MR spectroscopy in the diagnosis of intraventricular tumours. Fifty-two intraventricular tumours pertaining to 16 different tumour types were derived from our database. All cases had single-voxel proton MR spectroscopy performed at TE at both 30 and 136 ms at 1.5 T. The Mann-Whitney U test was used to search for the most discriminative datapoints each tumour type. Characteristic trends were found for some groups: high Glx and Ala in meningiomas (p < 0.001 and p < 0.01, respectively), high mobile lipids in metastasis (p < 0.001), high Cho in PNET (p < 0.001), high mI + Gly in ependymoma (p < 0.001), high NAC (p < 0.01) in the absence of the normal brain parenchyma pattern in colloid cysts, and high mI/Gly and Ala in central neurocytoma. Proton MR spectroscopy provides additional metabolic information that could be useful in the diagnosis of intraventricular brain tumors.

T he insula of Riel is located at the depth of the sylvian cistern, covered by the frontal, parietal, and temporal operculi. It overlies the striatum and thalamus, and it is covered by the trunk of the middle cerebral artery and its branches. 30,39 Insular gliomas are frequently encountered in neurosurgical practice, as the insula appears to be a preferential location for low-grade gliomas. An epidemiological study performed by Duffau and Capelle 9 showed that these lesions accounted for up to 25% of all low-grade gliomas and 10% of all high-grade gliomas.The insular region is a highly connected area, as an intricate network of afferent and efferent projections connect it with adjacent and distant cortical regions. 14,21,26,30 There are 2 prominent associative bundles that run under the in- obJect Little attention has been given to the functional challenges of the insular approach to the resection of gliomas, despite the potential damage of essential neural networks that underlie the insula. The object of this study is to analyze the subcortical anatomy of the insular region when infiltrated by gliomas, and compare it with the normal anatomy in nontumoral hemispheres. methods Ten postmortem human hemispheres were dissected, with isolation of the inferior fronto-occipital fasciculus (IFOF) and the uncinate fasciculus. Probabilistic diffusion tensor imaging (DTI) tractography was used to analyze the subcortical anatomy of the insular region in 10 healthy volunteers and in 22 patients with insular Grade II and Grade III gliomas. The subcortical anatomy of the insular region in these 22 insular gliomas was compared with the normal anatomy in 20 nontumoral hemispheres. results In tumoral hemispheres, the distances between the peri-insular sulci and the lateral surface of the IFOF and uncinate fasciculus were enlarged (p < 0.05). Also in tumoral hemispheres, the IFOF was identified in 10 (90.9%) of 11 patients with an extent of resection less than 80%, and in 4 (36.4%) of 11 patients with an extent of resection equal to or greater than 80% (multivariate analysis: p = 0.03). coNclusioNs Insular gliomas grow in the space between the lateral surface of the IFOF and uncinate fasciculus and the insular surface, displacing and compressing the tracts medially. Moreover, these tracts may be completely infiltrated by the tumor, with a total disruption of the bundles. In the current study, the identification of the IFOF with DTI tractography was significantly associated with the extent of tumor resection. If the IFOF is not identified preoperatively, there is a high probability of achieving a resection greater than 80%.

The vidian canal (VC), a bony tunnel in which the vidian artery and nerve pass, has been widely known as an important landmark to identify the anterior genu of the petrous carotid artery (AGPCA) especially during lateral extended endoscopic endonasal approachs (LEEEAs). The objectives of this study in the Japanese population are to describe the radiological anatomic features and relationships between VC and its surrounding structures, and discuss the clinical implications. We studied 231 high-resolution computed tomography (CT) scans with a slice thickness of 0.5 mm. All the patients had known sellar or parasellar pathologies but without any involvement of VC. The following VC-related parameters were examined: its length, relationship to AGPCA, course from the pterygopalatine fossa to the carotid canal, its position relative to the medial pterygoid plate and pneumatization pattern of the sphenoid sinus. Mean length of VC is 14.6 mm. There is more tendency of straight-running VC compared to other populations. VC locates infero-lateral to AGPCA in all the cases. The protrusion of VC and the paraclival carotid artery to the sphenoid sinus, as well as well-pneumatization of the sinus is also observed more frequently in almost a half of the population. Surgeons who perform LEEEAs in Japanese patients must know these anatomical features. The characteristics particular to Japanese populations may facilitate better identification of VC and exposure to AGPCA intraoperatively.

Purpose To provide a novel solution to reduce aerosol exposure in the operating room during endoscopic sinus and skull base procedures in the COVID-19 era. Methods We have designed a 3D printable midfacial mask that partially seals the nose, while allowing instrumentation during endoscopic transnasal surgery. The mask when connected to a vacuum system creates a constant negative pressure inside it, sucking out aerosols and gases generated during surgical procedures. Its effectiveness was tested using vapour exhalations by a human volunteer and drilling bone in a head model. The physical barrier effect was measured using fluorescein atomization in a head model. Results The pressure and airflow measured remained negative inside it in all the different situations tested. The mask was capable of completely evacuating human adult exhalation, and was more effective than the hand suction instrument. However, it was as effective as hand suction instrument at preventing aerosol spread from bone drilling. The physical barrier effect achieved a 72% reduction in the splatter created from the fluorescein atomization. Conclusions The mask effectively prevented the spread of aerosols and reduced droplet spread during simulated transnasal endoscopic skull base surgery in laboratory conditions. This device has potential benefits in protecting surgical personnel against airborne transmission of COVID-19 and could be useful in reducing chronic exposure to the hazard of surgical smoke. Electronic supplementary material The online version of this article (10.1007/s00405-020-06462-1) contains supplementary material, which is available to authorized users.

BACKGROUND An early maximal safe surgical resection is the current treatment paradigm for low-grade glioma (LGG). Nevertheless, there are no reliable methods to accurately predict the axonal intratumoral eloquent areas and, consequently, to predict the extent of resection. OBJECTIVE To describe the functional predictive value of eloquent white matter tracts within the tumor by using a pre- and postoperative intratumoral diffusion tensor imaging (DTI) tractography protocol in patients with LGG. METHODS A preoperative intratumoral DTI-based tractography protocol, using the tumor segmented volume as the only seed region, was used to assess the tracts within the tumor boundaries in 22 consecutive patients with LGG. The reconstructed tracts were correlated with intraoperative electrical stimulation (IES)-based language and motor subcortical mapping findings and the extent of resection was assessed by tumor volumetrics. RESULTS Identification of intratumoral language and motor tracts significantly predicted eloquent areas within the tumor during the IES mapping: the positive predictive value for the pyramidal tract, the inferior fronto-occipital fasciculus, the arcuate fasciculus and the inferior longitudinal fasciculus positive was 100%, 100%, 33%, and 80%, respectively, whereas negative predictive value was 100% for all of them. The reconstruction of at least one of these tracts within the tumor was significantly associated with a lower extent of resection (67%) as opposed to the extent of resection in the cases with a negative intratumoral tractography (100%) (P &lt; .0001). CONCLUSION Intratumoral DTI-based tractography is a simple and reliable method, useful in assessing glioma resectability based on the analysis of intratumoral eloquent areas associated with motor and language tracts within the tumor.