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Open access

Izumi Koyanagi, Yasuhiro Chiba, Hiroyuki Imamura, Masami Yoshino, and Toshimitsu Aida

BACKGROUND

Secondary Chiari malformation can be caused by various disorders associated with cerebrospinal fluid (CSF) leakage at the spinal level. In this report, the authors describe a rare case of secondary Chiari malformation caused by excessive CSF absorption through the enlarged spinal arachnoid villi–like structure.

OBSERVATIONS

A 20-year-old woman presented with progressive severe headache and posterior neck pain. Magnetic resonance imaging showed tonsillar herniation and decreased subarachnoid space around the spinal cord. A hypointense signal area was observed in the ventral spinal canal on a T2-weighted image. An axial image revealed multiple small, arachnoid cyst–like structures at the right T1 nerve root sleeve. Direct surgery revealed that the cyst-like structures were continuous with the arachnoid membrane and protruded into the abnormally large epidural venous sinus. The cyst-like structures were resected, and the dural sleeve was repaired using fascia. The patient showed good improvement of symptoms after surgery.

LESSONS

Excessive CSF absorption through the enlarged spinal arachnoid villi–like structure can cause secondary Chiari malformation. Neurosurgeons should be aware of this unusual mechanism of CSF leakage. Simple posterior fossa decompression will be ineffective or even harmful.

Open access

Aleksey Eroshkin, Dmytro Romanukha, and Serhiy Voitsekhovskyi

BACKGROUND

Extensive spinal epidural abscesses (SEAs) occupying three or more spinal regions are rare. This study aimed to address the key dilemma of surgical treatment for holospinal epidural abscesses, i.e., to determine the required scope of surgery and minimize surgical trauma with adequate purulent drainage.

OBSERVATIONS

Two patients with extensive SEAs were treated at the Neurosurgery Department of the Central Hospital of Ministry of Internal Affairs of Ukraine from 2018 to 2020. Both patients had a neurological deficit and general inflammatory response syndrome. Spinal magnetic resonance examinations were performed, showing that the first and second patients had extensive SEAs at T11/S1 and C2/L1, respectively. Both underwent minimally invasive abscess drainage via intra- and translaminar access at the most caudal point using an epidural silicone catheter in the cranial direction along the entire length of the abscess.

LESSONS

To achieve the key goal of extensive SEA treatment, i.e., to prevent the development of a persistent neurological deficit, immediate effective spinal canal decompression should be performed. Access method and scope should meet the requirements of spinal canal decompression and purulent content aspiration to the greatest possible extent while inducing minimal trauma.

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Igor Lima Maldonado, Christophe Destrieux, Eduardo Carvalhal Ribas, Bruna Siqueira de Abreu Brito Guimarães, Patrícia Pontes Cruz, and Hugues Duffau

OBJECTIVE

The sagittal stratum is divided into two layers. In classic descriptions, the stratum sagittale internum corresponds to optic radiations (RADs), whereas the stratum sagittale externum corresponds to fibers of the inferior longitudinal fasciculus. Although advanced for the time it was proposed, this schematic organization seems simplistic considering the recent progress on the understanding of cerebral connectivity and needs to be updated. Therefore, the authors sought to investigate the composition of the sagittal stratum and to detail the anatomical relationships among the macroscopic fasciculi.

METHODS

The authors performed a layer-by-layer fiber dissection from the superolateral aspect to the ventricular cavity in 20 cadaveric human hemispheres.

RESULTS

Diverse bundles of white matter were observed to contribute to the sagittal stratum and their spatial arrangement was highly consistent from one individual to another. This was the case of the middle longitudinal fasciculus, the inferior fronto-occipital fasciculus, the RADs, and other posterior thalamic radiations directed to nonvisual areas of the cerebral cortex. In addition, small contributions to the sagittal stratum came from the anterior commissure anteriorly and the inferior longitudinal fasciculus inferiorly.

CONCLUSIONS

A general model of sagittal stratum organization in layers is possible, but the composition of the external layer is much more complex than is mentioned in classic descriptions. A small contribution of the inferior longitudinal fasciculus is the main difference between the present results and the classic descriptions in which this bundle was considered to entirely correspond to the stratum sagittale externum. This subject has important implications both for fundamental research and neurosurgery, as well as for the development of surgical approaches for the cerebral parenchyma and ventricular system.

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Jacob S. Young, Andrew J. Gogos, Matheus P. Pereira, Ramin A. Morshed, Jing Li, Matthew J. Barkovich, Shawn L. Hervey-Jumper, and Mitchel S. Berger

OBJECTIVE

Tumor proximity to the ventricle and ventricular entry (VE) during surgery have both been associated with worse prognoses; however, the interaction between these two factors is poorly understood. Given the benefit of maximal tumor resection, it is imperative for surgical planning and technique to know if VE has negative consequences for patient survival and tumor dissemination.

METHODS

The University of California, San Francisco tumor registry was searched for patients with newly diagnosed and recurrent supratentorial glioblastoma (GBM) who underwent resection by the senior author between 2013 and 2018. Tumor location with respect to the subventricular zone (SVZ), size, and extent of resection were assessed using pre- and postoperative imaging. VE was determined by postoperative imaging and/or the operative report.

RESULTS

In this 200-patient cohort of newly diagnosed and recurrent GBM, 26.5% of patients had VE during resection. Patients with VE were more likely to have preexisting subependymal disease (41.5% vs 15.0%, p < 0.001). Comparing patients with VE to those without VE, there was no difference in the rates of postoperative hydrocephalus (1.9% vs 4.8%, p = 0.36), ventriculoperitoneal shunting (0% vs 3.4%, p = 0.17), pseudomeningoceles (7.5% vs 5.4%, p = 0.58), or subdural hematomas (11.3% vs 3.4%, p = 0.07). Importantly, rates of subsequent leptomeningeal disease (7.5% vs 10.2%, p = 0.57) and distant parenchymal recurrence (17.0% vs 23.1%, p = 0.35) were not different between the groups. Newly diagnosed patients with tumors contacting the SVZ (type I or II) had worse survival than patients with tumors that did not contact the SVZ (type III or IV) (1.27 vs 1.84 years, p = 0.014, HR 1.8, 95% CI 1.08–3.03), but VE was not associated with worse survival in these patients with high-risk SVZ type I and II tumors (1.15 vs 1.68 years, p = 0.151, HR 0.59, 95% CI 0.26–1.34).

CONCLUSIONS

VE was well tolerated, with postoperative complications being rare events. There was no increase in leptomeningeal spread or distant parenchymal recurrence in patients with VE. Finally, although survival was worse for patients with preoperative subependymal disease, VE did not change survival for patients with tumors contacting the ventricle. Therefore, VE during GBM resection is not associated with adverse patient outcomes and should be used by surgeons to enhance extent of resection.

CLASSIFICATION OF EVIDENCE Type of question: therapeutic; study design: retrospective cohort; evidence: class II.

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Karen Monuszko, Michael Malinzak, Lexie Zidanyue Yang, Donna Niedzwiecki, Herbert Fuchs, Carrie R. Muh, Krista Gingrich, Robert Lark, and Eric M. Thompson

OBJECTIVE

Patients with shunted hydrocephalus often accumulate high levels of radiation over their lifetimes during evaluation of hardware integrity. Current practice involves the use of a series of conventional radiographs for this purpose. Newer low-dose EOS radiography is currently used to evaluate scoliosis but has not been explored to evaluate shunt integrity on a large scale. The goal of this study was to compare the quality of imaging using EOS low-dose radiography to conventional radiography to evaluate shunt tubing.

METHODS

A retrospective chart review was performed on 57 patients who previously had both conventional radiographs and low-dose EOS images of their cerebral shunt tubing from 2000 to 2018. Patient demographics (age, sex, type of shunt tubing, primary diagnosis) were collected. Conventional radiographic images and low-dose EOS images were independently analyzed by a neurosurgeon and neuroradiologist in three categories: image quality, delineation of shunt, and distinction of shunt compared to adjacent anatomy.

RESULTS

All patients had shunted hydrocephalus due to spina bifida and Chiari type II malformation. Ratings of EOS and conventional radiographic images by both raters did not differ significantly in terms of image quality (rater 1, p = 0.499; rater 2, p = 0.578) or delineation of shunt (p = 0.107 and p = 0.256). Conventional radiographic images received significantly higher ratings than EOS on the ability to distinguish the shunt versus adjacent anatomy by rater 1 (p = 0.039), but not by rater 2 (p = 0.149). The overall score of the three categories combined was not significantly different between EOS and conventional radiography (rater 1, p = 0.818; rater 2, p = 0.186). In terms of cost, an EOS image was less costly than a conventional radiography shunt series ($236–$366 and $1300–$1547, respectively). The radiation dose was also lower for EOS images, with an effective dose of 0.086–0.140 mSv compared to approximately 1.6 mSv for a similar field of view with conventional radiography.

CONCLUSIONS

The image quality of low-dose EOS radiography does not significantly differ from conventional radiography for the evaluation of cerebral shunts. In addition, EOS affords a much lower radiation dose and a lower cost.

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Hiroki Ushirozako, Tomohiko Hasegawa, Yu Yamato, Go Yoshida, Tatsuya Yasuda, Tomohiro Banno, Hideyuki Arima, Shin Oe, Yuki Mihara, Tomohiro Yamada, Koichiro Ide, Yuh Watanabe, Keichi Nakai, Takaaki Imada, and Yukihiro Matsuyama

OBJECTIVE

Surgical site infection (SSI) after posterior spinal surgery is one of the severe complications that may occur despite administration of prophylactic antibiotics and the use of intraoperative aseptic precautions. The use of intrawound vancomycin powder for SSI prevention is still controversial, with a lack of high-quality and large-scale studies. The purpose of this retrospective study using a propensity score–matched analysis was to clarify whether intrawound vancomycin powder prevents SSI occurrence after spinal surgery.

METHODS

The authors analyzed 1261 adult patients who underwent posterior spinal surgery between 2010 and 2018 (mean age 62.3 years; 506 men, 755 women; follow-up period at least 1 year). Baseline and surgical data were assessed. After a preliminary analysis, a propensity score model was established with adjustments for age, sex, type of disease, and previously reported risk factors for SSI. The SSI rates were compared between patients with intrawound vancomycin powder treatment (vancomycin group) and those without (control group).

RESULTS

In a preliminary analysis of 1261 unmatched patients (623 patients in the vancomycin group and 638 patients in the control group), there were significant differences between the groups in age (p = 0.041), body mass index (p = 0.013), American Society of Anesthesiologists classification (p < 0.001), malnutrition (p = 0.001), revision status (p < 0.001), use of steroids (p = 0.019), use of anticoagulation (p = 0.033), length of surgery (p = 0.003), estimated blood loss (p < 0.001), and use of instrumentation (p < 0.001). There was no significant difference in SSI rates between the vancomycin and control groups (21 SSIs [3.4%] vs 33 SSIs [5.2%]; OR 0.640, 95% CI 0.368–1.111; p = 0.114). Using a one-to-one propensity score–matched analysis, 444 pairs of patients from the vancomycin and control groups were selected. There was no significant difference in the baseline and surgical data, except for height (p = 0.046), between both groups. The C-statistic for the propensity score model was 0.702. In the score-matched analysis, 12 (2.7%) and 24 (5.4%) patients in the vancomycin and control groups, respectively, developed SSIs (OR 0.486, 95% CI 0.243–0.972; p = 0.041). There were no systemic complications related to the use of vancomycin.

CONCLUSIONS

The current study showed that intrawound vancomycin powder was useful in reducing the risk of SSI after posterior spinal surgery by half, without adverse events. Intrawound vancomycin powder use is a safe and effective procedure for SSI prevention.

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Daiana R. Pur, Roy Eagleson, Marcus Lo, Michael T. Jurkiewicz, Andrea Andrade, and Sandrine de Ribaupierre

OBJECTIVE

Epilepsy affects neural processing and often causes intra- or interhemispheric language reorganization, rendering localization solely based on anatomical landmarks (e.g., Broca’s area) unreliable. Preoperative brain mapping is necessary to weigh the risk of resection with the risk of postoperative deficit. However, the use of conventional mapping methods (e.g., somatosensory stimulation, task-based functional MRI [fMRI]) in pediatric patients is technically difficult due to low compliance and their unique neurophysiology. Resting-state fMRI (rs-fMRI), a “task-free” technique based on the neural activity of the brain at rest, has the potential to overcome these limitations. The authors hypothesized that language networks can be identified from rs-fMRI by applying functional connectivity analyses.

METHODS

Cases in which both task-based fMRI and rs-fMRI were acquired as part of the preoperative clinical protocol for epilepsy surgery were reviewed. Task-based fMRI consisted of 2 language tasks and 1 motor task. Resting-state fMRI data were acquired while the patients watched an animated movie and were analyzed using independent component analysis (i.e., data-driven method). The authors extracted language networks from rs-fMRI data by performing a similarity analysis with functionally defined language network templates via a template-matching procedure. The Dice coefficient was used to quantify the overlap.

RESULTS

Thirteen children underwent conventional task-based fMRI (e.g., verb generation, object naming), rs-fMRI, and structural imaging at 1.5T. The language components with the highest overlap with the language templates were identified for each patient. Language lateralization results from task-based fMRI and rs-fMRI mapping were comparable, with good concordance in most cases. Resting-state fMRI–derived language maps indicated that language was on the left in 4 patients (31%), on the right in 5 patients (38%), and bilateral in 4 patients (31%). In some cases, rs-fMRI indicated a more extensive language representation.

CONCLUSIONS

Resting-state fMRI–derived language network data were identified at the patient level using a template-matching method. More than half of the patients in this study presented with atypical language lateralization, emphasizing the need for mapping. Overall, these data suggest that this technique may be used to preoperatively identify language networks in pediatric patients. It may also optimize presurgical planning of electrode placement and thereby guide the surgeon’s approach to the epileptogenic zone.

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Valeri Borger, Motaz Hamed, Julia Taube, Gülsah Aydin, Inja Ilic, Matthias Schneider, Patrick Schuss, Erdem Güresir, Albert Becker, Christoph Helmstaedter, Christian E. Elger, and Hartmut Vatter

OBJECTIVE

Temporal lobe epilepsy (TLE) is one of the most common forms of epilepsy. In approximately 30% of patients, seizures are refractory to drug treatment. Despite the achievements of modern presurgical evaluation in recent years, the presurgical prediction of seizure outcome remains difficult. The aim of this study was to evaluate the seizure outcome in patients with drug-refractory TLE who underwent resective temporal lobe surgery (rTLS) and to determine features associated with unfavorable postsurgical seizure outcome.

METHODS

Patients with medically refractory TLE who underwent rTLS between 2012 and 2017 were reviewed from the prospectively collected epilepsy surgery database. A retrospective analysis of clinical, radiological, neuropsychological, histopathological, and perioperative findings of 161 patients was performed. The patients were divided into two groups according to seizure outcome (group I, International League Against Epilepsy [ILAE] class 1; group II, ILAE class ≥ 2). For identification of independent risk factors for unfavorable postoperative seizure outcome (ILAE class ≥ 2), a multivariate logistic regression analysis was performed.

RESULTS

Seizure freedom (ILAE class 1) was achieved in 121 patients (75.2%). The neuropsychological evaluation demonstrated that losses in cognitive performance were more pronounced in verbal memory after resections in the left temporal lobe and in nonverbal memory after right-sided resections, whereas attention improved after surgery. Overall, postoperative visual field deficits (VFDs) were common and occurred in 51% of patients. There was no statistically significant difference in the incidence of VFD in patients with selective surgical procedures compared to the patients with nonselective procedures. The lack of MRI lesions and placement of depth electrodes were preoperatively identified as predictors for unfavorable seizure outcome.

CONCLUSIONS

rTLS is an effective treatment method in patients with refractory TLE. However, patients with a lack of MRI lesions and placement of depth electrodes prior to rTLS are at higher risk for an unfavorable postsurgical seizure outcome.

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Fangke Xie, Qiang Tan, Anyong Yu, Peiwen Guo, Ling Wang, Zongwei Zeng, Liang Liang, Jishu Xian, Hua Feng, and Zhi Chen

OBJECTIVE

Tissue plasminogen activator (tPA) fibrinolysis did not improve functional outcomes of patients with intraventricular hemorrhage (IVH), largely because of the unsatisfactory clot clearance. The presence of neutrophil extracellular traps (NETs) within the clot has been confirmed to impair tPA fibrinolysis, but the mechanism has been unclear. The authors hypothesized that cell-free DNA (cfDNA), the main framework of NETs, might be the important reason for the fibrinolysis resistance, and they validated the hypothesis, hoping to provide a new target to promote intraventricular fibrinolysis.

METHODS

First, cfDNA was detected in IVH clots by immunofluorescence staining in a rat model of IVH. Second, after blood (with or without exogenous cfDNA) intraventricular injection, IVH rats were given intraventricular infusion of 2 μl of saline, tPA, or tPA + DNase1 randomly. Then, the ventricular volume, animal behavior, and reactive astrocyte proliferation were assessed. Third, the IVH clots were collected for fibrinolysis assay in vitro. Finally, the effects of exogenous cfDNA in IVH were evaluated.

RESULTS

The presence of cfDNA in clots was observed as early as 1 hour after IVH. Compared with the whole-blood model, blood + cfDNA caused more severe ventricular dilation (day 7: blood 32.47 ± 2.096 mm3 vs blood + DNA 40.09 ± 2.787 mm3, p < 0.05), increased fibrinolysis resistance to tPA (day 7: tPA + DNA 26.04 ± 1.318 mm3 vs tPA 22.15 ± 1.706 mm3, p < 0.05), and further deteriorated the functional defects in rats (blood vs blood + DNA, p < 0.05). Degradation of cfDNA by DNase1 further enhanced the fibrinolysis effects on relieving the ventricular dilation (day 7: tPA + DNase1 11.67 ± 2.023 mm3 vs tPA, p < 0.05), improving the functional outcome (tPA vs tPA + DNase1, p < 0.05) and reducing periventricular astrocyte proliferation.

CONCLUSIONS

cfDNA impaired tPA fibrinolysis for IVH, and degradation of cfDNA may be a new target to improve this condition.