1. Avila MJ, Hurlbert RJ. Central cord syndrome redefined. Neurosurg Clin N Am 2021;32:353–63. Available from: https://doi.org/10.1016/j.nec.2021.03.007
The pathophysiology of CCS typically occurs in the setting of preexisting stenosis and involves a low-impact/low-velocity hyperextension injury to the neck. This causes buckling of the ligamentum flavum at the lordotic apex of the cervical spine (C4-C6) resulting in spinal cord compression against osteophytes and disks protruding into the anterior canal, displacing the spinal cord parenchyma into the less stenotic lateral recesses. The epicenter of compression is in the sagittal midline but spreads laterally proportional to the force involved and degree of preexisting stenosis. Spinal cord gray matter is affected first because of stretch and shear to the transversely oriented sensory afferents crossing the midline and the arteriole blood supply; their side-to-side horizontal trajectory makes them more susceptible to damage from lateral displacement than the longitudinally oriented white matter tracts. Gray matter injury results in sensory disturbance to the hands. With higher injury forces shear and contusion extend laterally to involve white matter tracts in a medial to- lateral preference. Motor weakness of the hands is precipitated from indiscriminate lateral corticospinal pathway involvement. With greater injury force there is additional lateral, anterior, and posterior white matter involvement affecting arm, leg, bowel, and bladder function.
Of all the controversies surrounding CCS, the management of incomplete SCI in this setting is one of the most widely debated. In his original narrative, Schneider and coworkers described the surgical management of CCS to be “contraindicated because spontaneous improvement or complete recovery may occur. Furthermore, operation has actually been known to harm these patients rather than improve them.” In the 65 years ensuing since this warning, the philosophy of a more conservative approach toward surgical intervention for CCS continues to be championed and despaired.
Even more widely debated than the need for decompressive surgery in CCS, is the timing of surgery. It is generally accepted that incomplete SCI from fracture dislocation should be treated by early decompression and stabilization. However, timing of surgery for incomplete CCS in the absence of acute fracture or dislocation varies widely from one institution and one surgeon to another. Some surgeons prefer to manage their patients’ weeks or months beyond the acute injury phase after they achieve a neurologic plateau. Evidence is limited and controversy common.
6 figures with MR
2. Harris L, Rajashekar D, Sharma P, et al. Performance of computed tomography-guided spine biopsy for the diagnosis of malignancy and infection. Oper Neurosurg 2021;21:126–30
Retrospective study of all consecutive patients who underwent a CT-guided spine biopsy at a UK teaching hospital between April 2012 and February 2019. Biopsies were performed by 3 consultant neuroradiologists for a lesion suggestive of either malignancy or infection. Data collection included patient factors, biopsy factors, further investigations required, and diagnosis. Data were analyzed using contingency tables, analysis of variance, unpaired t-test, chi-squared test, and Fisher’s exact test.
A total of 124 percutaneous biopsies were performed on 109 patients with a mean follow-up of 34.5 mo and a mean age of 66 yr. Approximately 32.3% (n = 40) of the biopsies investigated possible infection, and 67.7% investigated malignancy. The sensitivity for infected cases was 37.0%, and for malignancy 72.7%. The diagnostic accuracy was 57.5% and 78.6%, respectively. Complication rate was 1.6%. Neither needle gauge, anatomic level of the biopsy, or bone quality significantly affected the rate of positive biopsy.
In the cases where the CT-guided biopsy was nondiagnostic, a diagnosis was achieved by open biopsy (in 37.5% of cases), repeat CT-guided biopsy (31.3%), further blood cultures (25.0%), and repeat imaging (6.3%).
CT-guided biopsy has a vastly superior sensitivity for malignancy compared with suspected infection. These procedures may be painful, poorly tolerated, and are not entirely risk free. As such the authors advocate judicious use of this modality particularly in cases of suspected infection.
2 figures, 3 tables, no imaging
3. Wang SS, Selge F, Sebök M, et al. The value of intraoperative MRI in recurrent intracranial tumor surgery. J Neurosurg 2020;135(August):1–8
Identifying tumor remnants in previously operated tumor lesions remains a challenge. Intraoperative MRI (ioMRI) helps the neurosurgeon to reorient and update image guidance during surgery. The purpose of this study was to analyze whether ioMRI is more efficient in detecting tumor remnants in the surgery of recurrent lesions compared with primary surgery.
The cohort was divided into two groups: re-craniotomy and primary craniotomy. In contrast-enhancing tumors, tumor suspicion in ioMRI was defined as contrast enhancement in T1-weighted imaging. In non–contrast-enhancing tumors, tumor suspicion was defined as hypointensity in T1-weighted imaging and hyperintensity in T2-weighted imaging and FLAIR. In cases in which the ioMRI tumor suspicion was a false positive and not confirmed during in situ inspection by the neurosurgeon, the signal was defined as a tumor imitating ioMRI signal (TIM).
A total of 214 tumor surgeries met the inclusion criteria. The re-craniotomy group included 89 surgeries, and the primary craniotomy group included 123 surgeries.
The incidence of false-positive tumor imitating ioMRI signal was significantly higher in the re-craniotomy group (n = 11, 12%) compared with the primary craniotomy group (n = 5, 4%; p = 0.015), and in contrast-enhancing tumors was related to hemorrhages in situ.
The differentiation and identification of tumor remnants in surgery of recurrent tumor lesions is more challenging. There was evidence for a significantly increased incidence of tumor imitating ioMRI signal in the re-craniotomy group in comparison with the primary craniotomy group in this study. Most of these false-positive signals were contrast-enhancing signals, which in situ turned out to be hemorrhages. Hyperacute hemorrhage is difficult to distinguish in MRI sequences based on contrast enhancement. The usage of an SWI sequence for differentiation between residual tumor and hemorrhage during ioMRI could be advisable.
4 tables, 2 figures including MR
4. Shlobin NA, Shah VN, Chin CT, et al. Cerebrospinal fluid-venous fistulas: a systematic review and examination of individual patient data. Neurosurgery 2021;88:931–41. Available from: https://academic.oup.com/neurosurgery/article/88/5/931/6094070
SIH is an increasingly investigated cause of headaches. CSF leaks precipitate SIH due to resulting CSF hypovolemia. Decreased CSF volume leads to loss of CSF “buoyancy” on the brain, promoting traction or altering the integrity of the pain sensitive structures of the brain. Together with compensatory dilatation of intracranial venous structures, this causes headaches with orthostatic components. Traction, distortion, or compression of diencephalon, mesencephalon, brain lobes, and cranial nerves may result in the other symptoms of SIH. Compression of the eighth cranial nerve or altered pressure in inner ear perilymph or endolymph may result in cochleovestibular symptoms. Direct fistulae between the subarachnoid space and spinal epidural veins represent the most recently discovered cause of SIH.
Schievink et al have proposed a classification of spontaneous spinal CSF leaks contributing to SIH, with type 1a as ventral CSF leaks, type 1b as posterolateral CSF leaks, type 2a as simple meningeal diverticula, type 2b as complex meningeal diverticula or dural ectasia, and type 3 as direct CSF-venous fistulas. Type 3 CSF leaks were not associated with extradural CSF collections. Notably, nearly one-third of patients in their study had an indeterminate, of which greater than half had extradural CSF collections.
The authors conducted a systematic review using PubMed, Embase, Scopus, and Web of Science databases to identify studies discussing CSF-venous fistulas. Titles and abstracts were screened. Studies meeting prespecified inclusion criteria were reviewed in full.
Of 180 articles identified, 16 articles met inclusion criteria. Individual patient data was acquired from 7 studies reporting on 18 patients. CSF-venous fistula most frequently presented as positional headache. Digital subtraction myelography provided greatest detection of CSF-venous fistula in the lateral decubitus position and detected CSF-venous fistula in all individual patient cases. Dynamic computed tomography (CT) myelogram enabled detection and differentiation of CSF-venous fistulas from low-flow epidural leaks. The majority of fistulas were in the thoracic spine and slightly more common on the right. Epidural blood patch (EBP) provided temporary or no relief in all individual patients. Resolution or improvement of clinical symptoms and radiologic normalization were observed in all surgically treated patients.
3 figures, 2 tables
5. Smits M. MRI biomarkers in neuro-oncology. Nat Rev Neurol 2021;17:486–500. Available from: http://dx.doi.org/10.1038/s41582-021-00510-y
Biomarkers constitute a broad category of objective indicators of a healthy or disease state that should be measurable, precise, accurate and true. Although the value of biomarkers in both research and clinical practice is undisputed, clinical implementation of imaging biomarkers are far from commonplace. This sparsity can, in part, be attributed to a lack of rigorous biomarker evaluation, which has resulted in the almost non- existent regulatory qualification of imaging biomarkers. Conceptually, the requirements for imaging biomarkers are no different from those for biomarkers that are based on lab assays, but these are not trivial to meet, as the imaging field does not have a tradition of standardization across image acquisition, reconstruction, or post- processing approaches. These challenges do not mean that the requirements should be abandoned, but it is important that they are operationalized for this specific field of research and development. A roadmap towards achieving this aim was developed for the cancer field by the European Organization for Research and Treatment of Cancer (EORTC) and Cancer Research UK, and published in 2017. The roadmap provided 14 recommendations for the acceleration of imaging biomarker development that spanned grant submissions, study publications, validation (technical, biological and clinical) and qualification. The advancement of imaging biomarkers in radiology is driven by its two major societies, the European Society of Radiology (ESR) and the Radiological Society of North America (RSNA). ESR’s European Imaging Biomarkers Alliance (EIBALL) and RSNA’s Quantitative Imaging Biomarkers Alliance (QIBA) collaborate closely, with the aim of providing guidelines and setting standards for data acquisition and image processing, as well as the validation processes that are necessary for the development and eventual implementation of imaging biomarkers in clinical practice and clinical trials.
Apparent diffusion coefficient, dMRI is widely used in neuro- oncology, although rarely quantitatively. A European-wide survey found that maps of the apparent diffusion coefficient (ADC) — the most commonly used dMRI metric — were overwhelmingly used qualitatively (78% of respondents), by visual inspection only. To the author’s knowledge, a 2020 guideline for response assessment in pediatric high- grade glioma is the first and only clinical neuro- oncology guideline to include advanced MRI, that is, dMRI, in its response criteria — albeit only qualitatitively. ADC is considered to be a surrogate marker of cellular density and was inversely correlated with the Ki-67 labelling index in a retrospective study of high- grade astrocytoma. Information on the accuracy and precision of ADC measurement in the brain is scarce. The QIBA consensus profile of diffusion- weighted imaging states that a longitudinal difference of ≥11% can be attributed to true change. This figure is based on the results of three test–retest studies.
Despite extensive use of DSC pMRI in clinical practice, no broad consensus has been reached on acquisition technique, post- processing algorithms, analysis or interpretation. This lack of consensus has severely hampered application of DSC pMRI as an imaging biomarker thus far. In terms of acquisition, high reliability and reproducibility have been reported for various DSC approaches. Several studies have shown that differences in software or applied algorithms are a large source of variability in measured rCBV values. At present, the QIBA profile for DSC- MRI does not provide a claim for rCBV, owing to a lack of supporting literature. The extensive literature on rCBV in neurooncology provides a wide range of cut- off values for each of the various clinical indications for which pMRI is used, but no uniform threshold values have been established.
3 figures, 3 tables
6. Enriquez-Marulanda A, Gomez-Paz S, Salem MM, et al. Middle meningeal artery embolization versus conventional treatment of chronic subdural hematomas. Neurosurgery 2021;89:486–95. Available from: https://academic.oup.com/neurosurgery/article/89/3/486/6309701
Retrospective analysis of patients with cSDHs treated with MMA embolization in a single center from 2018 to 2019 was performed. Comparisons were made with a historical conventional treatment cohort from 2006 to 2016. Propensity score matching analysis was used to assemble a balanced group of subjects.
A total of 357 conventionally treated cSDH and 45 with MMA embolization were included. After balancing with propensity score matching, a total of 25 pairs of cSDH were analyzed. Comparing the embolization with the conventional treatment group yielded no significant differences in complications (4% vs 4%), clinical improvement (82.6% vs 83.3%), cSDH recurrence (4.3% vs 21.7%), overall re-intervention rates (12% vs 24%), modified Rankin scale >2 on last follow-up (17.4% vs 32%), as well as mortality (0% vs 12%). Radiographic improvement at last follow-up was significantly higher in the open surgery cohort.
The major finding of this study is that embolization is an effective treatment alternative for a select group of patients with cSDH. The latter was demonstrated due to the nonsignificantly lower treatment failure rates for the MMA embolization cohort, placing this novel therapy at least noninferior to conventional treatment.
The main weakness (as noted in the comment to the article) revolved around statistical power as the cohort only included 45 MMA patients that were reduced to 25 matching pairs in the PSM analysis.
4 figures, 5 tables
7. Tadros S, Kondrashov A, Namagiri S, et al. Pathological features of tumors of the nervous system in hereditary cancer predisposition syndromes: a review. Neurosurgery 2021;89:343–63. Available from: https://academic.oup.com/neurosurgery/article/89/3/343/6162972
Extensive neuropathology review of all the usual suspects, and many that will be less familiar names. This goes all the way from NF1 and NF2, Carney complex, VHL, Li-Fraumeni syndrome, Cowden syndrome, retinoblastoma, MEN variants.
12 figures (all pathology), 2 gigantic tables
8. Bae H, Suh S, Yoon WK, et al. Correlation of aneurysmal wall enhancement of unruptured intracranial aneurysms on high-resolution vessel-wall imaging with clinical indices and surgical findings. Neurosurgery 2021;89:420–27
Alert: abbreviation abuse
Many consider aneurysmal wall enhancement (AWE) on high resolution-vessel wall imaging (HR-VWI) as an imaging biomarker of unstable unruptured intracranial aneurysms (UIAs). So the authors wanted to evaluate the clinical value of different aneurysmal wall enhancement signal intensities (SIs) by assessing the correlation between the aneurysmal wall enhancement SIs and surgical findings and rupture risk assessment tools.
Several methods have been proposed for the evaluation of unstable unruptured intracranial aneurysms. They can be grouped into 2 types. The first type considers geometrical factors, such as size and location of the aneurysms. The population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from another aneurysm, site of aneurysm (PHASES) and earlier subarachnoid hemorrhage, location of the aneurysm, age >60 years, population, size of the aneurysm, shape of the aneurysm (ELAPSS) scores, 2 assessment tools for rupture risk, consider the geometric and ethnic factors (among others) and show significant results. They are currently used worldwide. The second type of methods involves a radiologic approach to visualize the histopathologic changes. This approach based on studies reporting that inflammation plays a major role in the formation, progression, and rupture of UIAs. High-resolution vessel-wall imaging (HRVWI) is an imaging tool currently being investigated for the evaluation of the unstable UIAs.
Twenty-six patients with 34 aneurysms who underwent surgical clipping were included. The corrected AWE SI was calculated by comparing T1-weighted images with post-gadolinium enhanced T1-weighted images. The correlation of AWE with PHASES and ELAPSS was evaluated.
The aneurysmal wall enhancement on HR-VWI was correlated with the PHASES and ELAPSS scores and the color. The stronger the aneurysmal wall enhancement, the higher were the PHASES and ELAPSS scores and the more abnormal was the color. The AWE might indicate the degree of inflammation.
4 figures, 3 tables
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