Fully automated delineation of the optic radiation for surgical planning using clinically feasible sequences

[EN] Quadrantanopia caused by inadvertent severing of Meyer's Loop of the optic radiation is a well-recognised complication of temporal lobectomy for conditions such as epilepsy. Dissection studies indicate that the anterior extent of Meyer's Loop varies considerably between individuals. Quantifying this for individual patients is thus an important step to improve the safety profile of temporal lobectomies. Previous attempts to delineate Meyer's Loop using diffusion MRI tractography have had difficulty estimating its full anterior extent, required manual ROI placement, and/or relied on advanced diffusion sequences that cannot be acquired routinely in most clinics. Here we present CONSULT: a pipeline that can delineate the optic radiation from raw DICOM data in a completely automated way via a combination of robust pre-processing, segmentation, and alignment stages, plus simple improvements that bolster the efficiency and reliability of standard tractography. We tested CONSULT on 696 scans of predominantly healthy participants (539 unique brains), including both advanced acquisitions and simpler acquisitions that could be acquired in clinically acceptable timeframes. Delineations completed without error in 99.4% of the scans. The distance between Meyer's Loop and the temporal pole closely matched both averages and ranges reported in dissection studies for all tested sequences. Median scan-rescan error of this distance was 1¿mm. When tested on two participants with considerable pathology, delineations were successful and realistic. Through this, we demonstrate not only how to identify Meyer's Loop with clinically feasible sequences, but also that this can be achieved without fundamental changes to tractography algorithms or complex post-processing methods.Advance Queensland, Grant/Award Number: R-09964-01; Fundacion Merck Salud; Proyecto Societat Catalana Neurologia; Ministerio de Economia, Industria y Competitividad of Spain, Grant/Award Number: DPI2017-87743-R; Red Espanola de Esclerosis Multiple, Grant/Award Numbers: RD12/0032/0002, RD12/0060/01-02, RD16/0015/0002, RD16/0015/0003; Spanish Government; Instituto de Salud Carlos III, Grant/Award Numbers: FIS 2015 PI15/00061, FIS 2015 - PI15/00587, FIS 2018 - PI18/01030Reid, LB.; Martínez-Heras, E.; Manjón Herrera, JV.; Jeffree, RL.; Alexander, H.; Trinder, J.; Solana, E.... (2021). Fully automated delineation of the optic radiation for surgical planning using clinically feasible sequences. Human Brain Mapping. 42(18):5911-5926. https://doi.org/10.1002/hbm.25658S59115926421

Colloid cyst of the third ventricle: a clinical review of 39 cases

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Postnatal development of arteriovenous malformations

Background: Arteriovenous malformations (AVMs) are commonly thought to be congenital malformations; however, patients usually present in adolescence or adulthood. This study was carried out to better understand the development of AVMs between birth and presentation. Methods: A retrospective review was performed of the medical records of all patients under 25 presenting to a single institution with an AVM or spontaneous intracerebral hemorrhage from 2000 to 2007. Results: Out of a total of 34 cases, 3 children were identified with delayed de novo appearance of an AVM after an intracerebral hemorrhage and normal initial angiography. The clinical and angiographic features are presented for these 3 patients and for an additional patient with AVM recurrence after complete surgical excision. Conclusions: In the light of these cases and a review of the literature, we suggest a hypothesis that AVMs develop postnatally, undergoing a period of growth in childhood or early adulthood, and that they may become symptomatic from the time of their earliest development. The trigger to growth may be shear stress stimulating growth factor expression by endothelial cells lining an arteriovenous fistula. Alternative stimuli, such as venous hypertension, cannot be ruled out. Copyrigh

Aminolevulinic acid (ALA)-protoporphyrin IX fluorescence guided tumour resection. Part 1: Clinical, radiological and pathological studies

The intraoperative identification and resection of glioma is a significant and important challenge in neurosurgery. Complete resection of the enhancing tumour increases the median survival time in glioblastoma compared to partial glioma resection; however, it is achieved in fewer than half of eligible patients when conventional tumour identification methods are used. Increasing the incidence of complete resection, without causing excess morbidity, requires new methods to accurately identify neoplastic tissue intraoperatively, such as use of the drug 5-amino-levulinic acid (ALA). After ALA ingestion, the fluorescent molecule protoporphyrin IX (PpIX) accumulates in high grade glioma, allowing the neurosurgeon to more easily detect and accurately resect tumour. The utility of ALA has been demonstrated in a large, multicentre phase III randomised control trial of 243 patients with high grade glioma. ALA use led to a significant increase in the incidence of complete resection (65% compared to 36%), improved progression-free survival at 6 months (41% compared to 21%), fewer reinterventions, and delayed onset of neurological deterioration. This review provides a broad assessment of ALA-PpIX fluorescence-guided resection, with Part 1 focusing on its clinical efficacy, and correlations with imaging and histology. The theoretical, biochemical and practical aspects of ALA use are reviewed in Part 2

Ten tips for teaching in the theatre tearoom: shifting the focus from teaching to learning

Educational encounters between surgeons and trainees are often brief, spontaneous, opportunistic events. In spite of their vast teaching experience, very few surgeons have had educational training that enables them to optimise such opportunities. This article reviews the literature on medical education and adult learning, and makes practical suggestions about how surgeons can best help trainees to learn. The most important ideas, such as creating a supportive learning environment, actively engaging the learner, and providing constructive feedback, are relevant to any teaching and learning, but are particularly applicable to informal, on-the-job educational encounters such as teaching in the theatre tearoom

STA-MCA bypass for symptomatic carotid occlusion and haemodynamic impairment

Patients with carotid artery occlusion and haemodynamic insufficiency have a high risk of stroke. Cerebral revascularization surgery improves cerebral blood flow, but it remains unclear whether this reduces the risk of stroke. This study assesses the long-term outcome of patients undergoing superficial temporal artery to middle cerebral artery (STA–MCA) bypass for symptomatic carotid occlusion. The long-term clinical follow-up and haemodynamic reserve, measured by 99Technetium single photon emission computed tomography (Tc99 SPECT) scan with acetazolamide challenge, were reviewed for 19 consecutive patients before and after STA–MCA bypass. The stroke rate after bypass surgery was 8% per year. In patients waiting for surgery, the stroke rate was 18% per year. Cerebral perfusion assessed with SPECT scan improved in 88% of patients. These results are consistent with the high risks of haemodynamic infarction in untreated patients and a benefit from revascularization surgery. The percentage annual stroke risk compares favourably with an 18% rate reported for patients with internal carotid artery occlusion and impaired cerebrovascular reserve.10 page(s

Management of breast cancer brain metastases: a practical review

Brain metastases are a common, and frequently challenging, clinical problem in the contemporary management of metastatic breast cancer. While the management of extracranial metastatic breast cancer is now strongly defined by tumour phenotype, this approach is not so well defined for brain metastases. We review available evidence regarding management of brain metastases, including the limited breast-cancer-specific data. A framework for management according to breast cancer phenotype is proposed