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1. Huynh J, Donovan J, Phu NH, et al. Tuberculous meningitis: progress and remaining questions. Lancet Neurol 2022;21:45 0–64. Available from: http://dx.doi.org/10.1016/S1474-4422(21)00435-X

Tuberculosis affects 10 million people globally each year, of which an estimated 2–5% have tuberculous meningitis. The true incidence of tuberculous meningitis is unknown; however, tuberculous meningitis is the leading cause of bacterial brain infections in settings with a high tuberculosis burden, disproportionately affecting young children and individuals with HIV. Here, the authors review advances made in the past 7 years concerning the pathogenesis, diagnosis, and treatment of tuberculous meningitis, emphasizing areas of uncertainty and updating Reviews published in The Lancet Neurology in 2005 and 2013. This Review focuses mainly on adult tuberculous meningitis and briefly emphasizes novel research advances in pediatric tuberculous meningitis, including important clinical trials on its management.

Confirming a diagnosis of tuberculous meningitis is challenging because it requires detection of M tuberculosis in CSF. CSF Ziehl-Neelsen staining and microscopy is rapid, inexpensive, and can be performed in many laboratories with few resources. However, a study of 618 individuals with tuberculous meningitis in Vietnam, South Africa, and Indonesia reported that its sensitivity was generally poor (ie, approximately 30%) and was not improved by adaptations to enhance staining of intracellular bacteria. PCR-based tests, such as GeneXpert MTB/RIF and GeneXpert MTB/RIF Ultra (Cepheid, Sunnyvale, CA, USA), are rapid and offer identification of rifampicin resistance. Although these tests are useful when positive, the negative predictive values of GeneXpert MTB/RIF is insufficient to rule out tuberculous meningitis. Large-volume CSF sampling and meticulous processing steps are essential to optimize the performance of smear, culture, and nucleic acid amplification tests.

Brain MRI features that predict future outcome and treatment response are poorly defined. Tools based on artificial intelligence and machine learning are being developed to enable an unbiased and automated assessment of brain images and provide guidance to clinicians on treatment response and outcomes. Artificial intelligence and machine learning, particularly when applied to digital brain imaging, have been implemented to devise diagnostic, complication prediction, and outcome prediction systems for neurodegenerative disorders, demyelinating disorders of the brain, and acute ischemic strokes. Machine learning in tuberculous meningitis is likely to assist in diagnosis and individualized treatment decisions in the future.

1 figure, 3 tables, no imaging

2. Ehresman J, Catapano JS, Baranoski JF, et al. Treatment of spinal arteriovenous malformation and fistula. Neurosurg Clin N Am 2022;33:19 3–206. Available from: https://doi.org/10.1016/j.nec.2021.11.005

Multiple classification systems have been created to separate spinal arteriovenous malformations (AVMs) based on location, angioarchitecture, and size. The first classification system was created by Di Chiro in 1971 after Di Chiro and colleagues first reported 4 years earlier on the selective angiography of spinal AVMs. Lesions were classified into 3 categories: type I, single-vessel arteriovenous fistula (AVF); type II, glomus AVM; and type III, juvenile AVM. More than 15 years later, in 1987, Di Chiro’s group added a fourth type of AVM, those with direct feeders from the anterior spinal artery (ASA). In 2002, Spetzler and colleagues created a schema based on surgical experience that classified the vascular lesions by anatomic locations surrounding or within the spinal cord. This classification is the one primarily used in this review, and it includes (1) extradural AVFs, (2) intradural ventral AVFs, (3) intradural dorsal AVFs, (4) extradural-intradural AVMs, (5) intramedullary AVMs, and (6) conus medullaris AVMs.

Extradural AVFs involve a direct connection between a radicular artery branch and the epidural venous plexus. Venous engorgement or congestion can cause increased retrograde pressure in the medullary veins within the spinal cord, leading to compressive symptoms.

Intradural dorsal AVFs, also known as type I AVMs or spinal dural AVFs, are the most common type of spinal AV shunt. These fistulas are located at the dural nerve root sleeve and involve a radicular feeder artery with a direct connection to a medullary vein.

Intradural ventral AVFs, often referred to as perimedullary type IV AVFs, involve a direct connection between the ASA and the coronal (pial) venous plexus.

Extradural-intradural AVMs, otherwise known as type III, juvenile, or metameric AVMs, are often large and complex lesions spanning multiple tissue layers.

Intramedullary AVMs, or type II glomus AVMs, include a classic nidus within the spinal cord and may include multiple arterial branches of the ASA and the posterior spinal artery (PSA) that drain into the coronal venous plexus.

Conus medullaris AVMs are complex lesions with multiple direct feeder arteries from the ASA, PSA, and radicular arteries that drain into a complex venous network near the conus medullaris and cauda equina.

6 figures (illustrations) and 6 tables listing relevant publications for each vascular malformation

3. Dono A, Alfaro-Munoz K, Yan Y, et al. Molecular, histological, and clinical characteristics of oligodendrogliomas: a multi-institutional retrospective study. Neurosurgery 2022;90:51 5–22

Oligodendrogliomas comprise 5.3% of gliomas. Based on the 2016 World Health Organization (WHO) fourth revised edition, the diagnosis of oligodendroglioma requires IDH1/IDH2 mutation and 1p/19q-co- deletion.  Recent studies have shown that genetic alterations can correlate with outcomes in molecularly defined gliomas (eg, CDKN2A/B loss in isocitrate dehydrogenase [IDH]-mutant astrocytomas and EGFR amplification or TERT promoter mutation in IDH wild-type astrocytomas). However, studies analyzing mutations that correlate with survival in molecular oligodendrogliomas (mODG) are limited. One hundred seven mODGs (2008-2019) diagnosed at 2 institutions were included. A retrospective review of clinical characteristics, molecular alterations, treatments, and outcomes was performed.

The authors results show a benefit of TMZ vs observation in progression-free survival (PFS). No difference in PFS or overall survival (OS) was observed between radiation and radiation/TMZ. PIK3CA mutations were detected in 15 (14%) mODG, and shorter OS was observed in PIK3CA-mutant compared with PIK3CA wild-type mODGs (10.7 years vs 15.1 years, P = .009).

In this study, there was no benefit of RT, TMZ, or the combination of both in OS. Despite the small sample size, the results are concordant with a recent retrospective study which showed no benefit from TMZ, RT, or their combination in WHO grade 2 mODG.²⁰ Importantly, recent studies have demonstrated that TMZ is an independent risk factor for malignant transformation and mismatch repair pathway defects, which in turn could lead to worse survival.

2 tables, 1 figure, no imaging

4. Delgardo M, Higgins D, McCormick KL, et al. Clinical characteristics, outcomes, and pathology analysis in patients with dorsal arachnoid web. Neurosurgery 2022;90:58 1–87. Available from: https://journals.lww.com/10.1227/neu.0000000000001884

Seventeen cases of DAW between 2015 and 2019 at a tertiary medical center were retrospectively identified through a case log search. Patient characteristics, preoperative imaging, operative notes, and pathology reports were collected.

The mean age of the cohort was 50.5 years (IQR = 16) and presented primarily with back pain (64.7%). On imaging, all patients were found to have the “scalpel sign,” and nearly half had a syrinx present (41.2%). All DAWs were located in the thoracic spine, with the most common location being the midthoracic (70.6%). The mean follow-up length for all patients was 4.3 months. There were no preoperative symptoms significantly associated with postoperative symptom resolution; however, a trend was noted with the presence of a preoperative syrinx. Pathology samples consistently demonstrated fibroconnective or collagenous tissue with no evidence of inflammation or neoplasm.

3 figures, 4 tables with MRI

See also from the March podcast: Voglis S, Romagna A, Germans MR, Carreno I, Stienen MN, Henzi A, et al. Spinal arachnoid web—a distinct entity o