The foramen spinosum: a landmark in middle fossa surgery

The foramen spinosum is an easily identifiable landmark in microsurgery of the middle cranial fossa, and knowledge of the variations in its relationship to the surrounding neurovascular structures is important when operating in this area. We studied the anatomical relationship of the foramen spinosum to the foramen ovale, the mandibular branch of the trigeminal nerve, the greater superficial petrosal nerve, and the petrous part of the internal carotid artery in 12 cadaver heads. We also tried to define an external landmark for early identification of the location of the foramen spinosum in ten dry skulls. We found considerable variations in the anatomy around the foramen spinosum. This knowledge may improve the identification and preservation of the neurovascular structures when using approaches to the middle cranial foss

The anatomy of neuroepithelial tumours

Many neurological conditions conceal specific anatomical patterns. Their study contributes to the understanding of disease biology and to tailored diagnostics and therapy. Neuroepithelial tumours exhibit distinct anatomical phenotypes and spatiotemporal dynamics that differ from those of other brain tumours. Brain metastases display a preference for the cortico-subcortical boundaries of watershed areas and have a predominantly spherical growth. Primary CNS lymphomas localize to the white matter and generally invade along fibre tracts. In neuroepithelial tumours, topographic probability mapping and unsupervised topological clustering have identified an inherent radial anatomy and adherence to ventriculopial configurations of specific hierarchical orders. Spatiotemporal probability and multivariate survival analyses have identified a temporal and prognostic sequence underlying the anatomical phenotypes of neuroepithelial tumours. Gradual neuroepithelial de-differentiation and declining prognosis follow (i) an expansion into higher order radial units; (ii) a subventricular spread; and (iii) the presence of mesenchymal patterns (expansion along white matter tracts, leptomeningeal or perivascular invasion, CSF spread). While different pathophysiological hypotheses have been proposed, the cellular and molecular mechanisms dictating this anatomical behaviour remain largely unknown. Here we adopt an ontogenetic approach towards the understanding of neuroepithelial tumour anatomy. Contemporary perception of histo- and morphogenetic processes during neurodevelopment permit us to conceptualize the architecture of the brain into hierarchically organized radial units. The anatomical phenotypes in neuroepithelial tumours and their temporal and prognostic sequences share remarkable similarities with the ontogenetic organization of the brain and the anatomical specifications that occur during neurodevelopment. This macroscopic coherence is reinforced by cellular and molecular observations that the initiation of various neuroepithelial tumours, their intratumoural hierarchy and tumour progression are associated with the aberrant reactivation of surprisingly normal ontogenetic programs. Generalizable topological phenotypes could provide the basis for an anatomical refinement of the current classification of neuroepithelial tumours. In addition, we have proposed a staging system for adult-type diffuse gliomas that is based on the prognostically critical steps along the sequence of anatomical tumour progression. Considering the parallels in anatomical behaviour between different neuroepithelial tumours, analogous staging systems may be implemented for other neuroepithelial tumour types and subtypes. Both the anatomical stage of a neuroepithelial tumour and the spatial configuration of its hosting radial unit harbour the potential to stratify treatment decisions at diagnosis and during follow-up. More data on specific neuroepithelial tumour types and subtypes are needed to increase the anatomical granularity in their classification and to determine the clinical impact of stage-adapted and anatomically tailored therapy and surveillance

Clival Chondrosarcoma Associated With an Intra-Axial Cystic Medullary Lesion Responsive to Steroids

Introduction: Here we present a 75-year-old patient who was admitted with acute-onset right-sided hemiparesis, dysphagia, dysarthria and nystagmus. Repeated MRI scans showed two lesions with contact to one another: one solid stationary extra-axial lesion at the caudal part of the clivus and a rapidly growing intra-axial cystic lesion at the level of the medulla oblongata. Biopsy of the solid lesion demonstrated a low-grade chondrosarcoma, while no tissue sample of the cystic lesion could be retrieved. After initiation of dexamethasone therapy the cystic lesion markedly regressed.Background: A literature search on published cases with the same combination of a stationary solid extra-axial mass at the caudal part of the clivus and a growing intra-axial cystic mass in the medulla oblongata was negative, indicating that the case described here is both unique and novel.Discussion: Considering the rapid progression of symptoms and growth on MR-imaging in combination with the marked response to steroids, an inflammatory response linked to the chondrosarcoma is most likely. At the same time other possible explanations as a second neoplasm, an abscess or an ischemic lesion seem unlikely.Concluding remarks: This case underlines an unusual complication of a rare brainstem tumor and outlines both the differential diagnosis and potential treatment options. For such cystic lesions in combination with chondrosarcoma, a treatment course with steroids should be considered along with surgical exploration necessary to obtain the diagnosis and for potential reduction of mass-effect on the medulla oblongata

Spontaneous otogenic intracerebral pneumocephalus: case report and review of the literature

Pneumocephalus is commonly associated with head and facial trauma, ear infection or surgical interventions. We describe the rare case of a spontaneous pneumocephalus arising from lateral mastoid air cells. A 48-year-old man presented with a 10-day history of sudden, repetitive, ‘hammering-like' acoustic sensations in his left ear that were followed by word-finding difficulties and loss of vision in the right visual field. Imaging revealed a large, left temporal pneumatocele associated with a small acute intracerebral hemorrhage. Left temporal and subtemporal craniotomy and decompression were performed. Further exploration confirmed a dural and osseous defect in the anterolateral surface of the mastoid that was consecutively closed watertight. Although extremely rare, a spontaneous pneumocephalus with mastoidal origin should be considered as a possible diagnosis in patients with suggestive acoustic phenomena and other non-specific neurological symptom

Metastases in Meckel's Cave: A Challenge of Differential Diagnosis

Metastases in Meckel's cave are a rare tumor entity and should be considered as important differential diagnosis, especially if the patient presents with trigeminal neuralgia and suffers from a known primary malignancy. We present three cases of patients with secondary trigeminal neuralgia caused by a metastasis in Meckel's cave, treated by microsurgery and fractionated radiation therapy. Differential diagnoses are discussed on the basis of preoperative neuroradiological imaging. MRI is the preferred diagnostic modality, whereas complementary CT may be needed for evaluation of early bone invasio

Bifocal extra- and intradural melanocytoma of the spine: case report and literature review

Background: Spinal melanocytoma is one of the most infrequent space-occupying lesions of the central nervous system. To the best of our knowledge, this is the first report of primary bifocal intradural melanocytoma of heterogenous pathological grade to date. Case description: We report the case of a 43-year old patient with primary bifocal melanocytoma, clinically and radiologically resembling benign schwannoma. The patient presented with myeloradiculopathy of the left C3 dermatome. Magnetic resonance imaging of the upper spine revealed two space-occupying lesions with paraspinal extension, initially diagnosed as neurofibroma. Definitive histopathological classification of both lesions was melanocytoma. Both tumours were only partially removed due to adherence to surrounding structures. The patient underwent stereotactic external beam irradiation (EBR). Follow-up at 1year after surgery revealed no recurrence and the patient remained free of symptoms. The clinical, radiological and pathological features of this rare tumour entity are presented and the available literature is reviewed. Conclusions: Intradural melanocytoma, although exceedingly rare, requires a thorough work-up to exclude malignant melanoma. With only two previous reports of multifocal melanocytoma published in the literature, standard therapy has not yet been established and complete surgical removal remains the modality of choice. Patients should be closely monitored to detect local recurrence or malignant degeneration. EBR may be considered in cases where total excision is not achievable and reduces risk of local recurrence

Laserablation für Temporallappenepilepsien

Die interstitielle thermale Lasertherapie findet immer häufiger bei refraktären Epilepsieerkrankungen Anwendung. Dabei handelt es sich um eine neuartige minimal invasive Methode, mit der mittels Magnetresonanztomografie unter direkter Kontrolle von Temperatur und Ablation auch tief im Gehirn gelegene Areale behandelt werden können. Dieser Beitrag fasst den aktuellen Wissensstand zur Laserbehandlung von Temporallappenepilepsien zusammen und vergleicht diese Technik mit anderen epilepsiechirurgischen Optionen

Surgical resection of pediatric skull base meningiomas

Purpose: Meningiomas in children are rare, especially those located at the skull base. In this study, we report our experience of meningioma surgery in the pediatric population and compare our findings of skull base (SB) versus non-skull base (NSB) meningiomas. Methods: From our database of 724 surgically treated meningioma patients at the University Hospital, Zurich between 1995 and 2010, 12 patients under 18years of age were identified. Data for those patients was retrospectively collected through chart review. A descriptive comparison between SB and NSB meningiomas was undertaken to determine statistical significance. Results: In all 12 children (seven males, five females; mean age 12.2 ± 4.3years), surgical removal of the meningioma was performed microsurgically with a mean follow-up of 53months (range 12-137months). Of the 12 tumors, six were located in the SB and six in the NSB. Comparing SB to NSB lesions, the mean age was 11 ± 3.8 versus 14 ± 4.6years, male/female gender distribution was 5:1 compared to 1:5, mean tumor size was 7.5 ± 6.2 versus 26 ± 15.8cm2 (p = 0.03), and mean surgery time was 347 versus 214min. While WHO grade was similar for both groups, the Simpson grade revealed more extensive resection for NSB meningiomas. The Glasgow Outcome Scale at last follow-up was favorable for both groups. Conclusions: Meningioma surgery was safe with favorable outcomes. SB meningiomas were significantly smaller in size, were less likely to undergo complete resection, and had a predilection for younger, male patient

A Spiking Neural Network (SNN) for detecting High Frequency Oscillations (HFOs) in the intraoperative ECoG

To achieve seizure freedom, epilepsy surgery requires the complete resection of the epileptogenic brain tissue. In intraoperative ECoG recordings, high frequency oscillations (HFOs) generated by epileptogenic tissue can be used to tailor the resection margin. However, automatic detection of HFOs in real-time remains an open challenge. Here we present a spiking neural network (SNN) for automatic HFO detection that is optimally suited for neuromorphic hardware implementation. We trained the SNN to detect HFO signals measured from intraoperative ECoG on-line, using an independently labeled dataset. We targeted the detection of HFOs in the fast ripple frequency range (250-500 Hz) and compared the network results with the labeled HFO data. We endowed the SNN with a novel artifact rejection mechanism to suppress sharp transients and demonstrate its effectiveness on the ECoG dataset. The HFO rates (median 6.6 HFO/min in pre-resection recordings) detected by this SNN are comparable to those published in the dataset (58 min, 16 recordings). The postsurgical seizure outcome was "predicted" with 100% accuracy for all 8 patients. These results provide a further step towards the construction of a real-time portable battery-operated HFO detection system that can be used during epilepsy surgery to guide the resection of the epileptogenic zone.Comment: 11 pages, 3 figures, 2 tables. The results of this publication were obtained by simulating our hardware platform, built for online processing of biological signals. This hardware combines neural recording headstages with a multi-core neuromorphic processor arxiv.org/abs/2009.1124