Carlstrom, Lucas P.

OBJECTIVE Calcium phosphate cement (CPC) use has been previously described as a strategy to reduce the rates of pseudomeningocele and CSF leakage following skull base surgery. The authors aimed to present their institutional experience with CPC in retrosigmoid craniotomy and perform a systematic review of the literature to determine the effectiveness of CPC in reducing postoperative complications, including pseudomeningocele and craniotomy-site CSF leakage. METHODS A retrospective single-institution cohort study of patients who underwent retrosigmoid craniotomy with and without CPC cranioplasty from January 2017 to April 2024 was performed. A systematic literature review and meta-analysis of CPC use in retrosigmoid craniotomy was also performed. RESULTS Of 336 patients who underwent retrosigmoid craniotomy, 193 (57%) were female and the median age at surgery was 55 years (range 18–81 years). The median follow-up duration was 23 months (range 3–80 months). CPC was used to seal the edge of the craniotomy in 66 patients (20%). Among all patients, 50 (15%) experienced a postoperative complication, and 28 (8%) were wound-specific complications. Patients in the non-CPC group experienced significantly more postoperative wound-specific complications than those in the CPC group (10% vs 0%, p = 0.002). Specifically, pseudomeningocele occurred in 0 patients (0%) in the CPC group compared with 24 patients (9%) in the non-CPC group (p = 0.006), which progressed to CSF leaks at the craniotomy site in 6 patients (p = 0.60). Additionally, no patients (0%) in the CPC group experienced wound infection, dehiscence, or breakdown compared with 10 patients (4%) in the non-CPC group (p = 0.22). Five patients (8%) in the CPC group reported prolonged mild incisional pain at the craniotomy site, and there were no instances of major complications related to the CPC. In the meta-analysis, 10 studies met the inclusion criteria, yielding a total of 2166 patients (including the current study), 1101 of whom received CPC. In the pooled analysis, CPC was significantly associated with lower risk of CSF leakage at the craniotomy site (OR 0.23, 95% CI 0.13–0.42; p < 0.01) and lower risk of infection (OR 0.17, 95% CI 0.08–0.38; p < 0.01). CONCLUSIONS CPC use in retrosigmoid craniotomies could be a safe and effective strategy to reduce the incidence of pseudomeningocele and craniotomy-site CSF leakage, leading to lower rates of wound-related complications and infection.

BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) is increasingly used as a primary treatment modality for intracranial meningiomas. We aim to describe clinical outcomes after single-fraction SRS for sporadic intracranial meningiomas. METHODS: A prospectively maintained database was reviewed for patients with sporadic meningiomas who underwent SRS (Gamma Knife) as primary treatment modality from April 1997 to February 2022. Primary outcomes included progression-free survival (PFS) and treatment-related complications. RESULTS: Six hundred sixteen patients (653 tumors) underwent SRS with median follow-up of 6.3 years (interquartile range [IQR] 3.1-10.5 years). The median tumor volume was 4.5 cm 3 (IQR 2.0-8.0 cm 3 ). The median margin dose was 15.0 Gy (IQR 14.0-16.0). In-field progression was noted in 7 tumors (1.1%) and marginal progression in 2 tumors (0.3%) for a raw failure rate of 1.4%. PFS estimates at 5, 10, and 15 years were 99.8%, 99.0%, and 93.2%, respectively. Factors associated with reduced PFS on univariable analysis included older age (hazards ratio [HR] 1.14, 95% CI, 1.05-1.22, P < .001), male sex (HR 5.44, 95% CI, 1.45-20.4, P = .010), increasing tumor volume (HR 1.06, 95% CI, 0.99-1.13, P = .028), and lower tumor margin dose (HR 0.65, 95% CI, 0.43-0.97, P = .006). Treatment-related complications were noted in 56 patients (9.1%), of which 45 (7.3%) were temporary, 5 (0.8%) were minor, and 6 (1.0%) were permanent and/or required intervention. Radiosurgical parameters associated with treatment-related complications included increased number of isocenters (odds ratio [OR] 1.09, 95% CI, 1.04-1.14, P < .001), higher 12-Gy volume (OR 1.06, 95% CI, 1.03-1.09, P < .001), larger tumor volume (OR 1.06, 95% CI, 1.02-1.10, P < .001), and lower maximal dose (OR 0.90, 95% CI, 0.82-0.98, P = .11). CONCLUSION: SRS is effective as a primary treatment modality for sporadic, small-volume to medium-volume intracranial meningiomas. Pre-emptive SRS should be discussed as a safe management strategy compared with observation alone for incidentally discovered meningiomas.

BACKGROUND: Surgical intervention remains an important option in the management of vestibular schwannoma (VSs). Development of a systematic approach to choose the most appropriate route for this intervention, based on existing published evidence, is an important goal. OBJECTIVE: To review the literature published since the 2018 Congress of Neurological Surgeons Guideline on surgical intervention for patients with sporadic VSs and use this information to update that set of recommendations. METHODS: The literature in the PubMed and MEDLINE databases from January 2015 through May 20, 2022, was searched for manuscripts pertaining to surgical intervention for VSs. Those manuscripts meeting inclusion criteria were then analyzed for creation of recommendations in response to a set of updated questions. RESULTS: The resultant findings included a considerable amount of data that did not alter the recommendations form the 2018 publication on this topic. Thus, recommendations stating hearing preservation surgery through the middle fossa or retrosigmoid approach may be considered in individuals with good preoperative hearing as an alternative to simple observation remain. In addition, if microsurgical resection is necessary after stereotactic radiosurgery, it is recommended that patients be counseled that there is an increased likelihood of a subtotal resection and decreased facial nerve function. In some questions, insufficient data were present to create an answer and that is stated. CONCLUSION: This guideline demonstrates surgical intervention for VSs and represents a range of options, and the choice of the intervention depends on the specific aspects of the lesion and the individual that harbors them. Objective refinement of those choices will require thoughtful research design by investigations that wish to address those items for which we still have insufficient information. The full guideline can be seen online at https://www.cns.org/guidelines/treatment-adults-vestibular-schwannoma/7-surgical-resection-treatment-of-patients-with-ve-2

BACKGROUND: Imaging is a critical aspect of vestibular schwannoma (VS) management, influencing essentially every aspect of care including diagnosis, surveillance, treatment decision making, and follow-up after either resection or stereotactic radiosurgery. Despite this, treatment protocols are heterogeneous, and frequently based on historical practices, or low-quality evidence. OBJECTIVE: To update evidence-based guidelines for the use of imaging in the clinical management of patients with VS published by the Congress of Neurological Surgeons in 2018. METHODS: Systematic review of the literature published from 1/1/2015 to 5/20/2022 regarding imaging protocols for VS management. Salient questions were identified by a writing group of diverse individuals with topic-specific expertise. Questions were validated by the Congress of Neurological Surgeons Guidelines Committee. Following systematic review, literature tables and summary statements pertinent to the study questions were generated by the writing group, which underwent subsequent evaluation and revision by the task force before formalization. RESULTS: Seven questions were formulated; adequate literature was identified to formulate updated recommendations for 6 of these. Search strategy identified 1143 unique records, of which 109 underwent full-text review, and 57 were included in this study. Most studies provided level III evidence, with rare level II studies noted, yielding level III recommendations. CONCLUSION: The current evidence base for imaging protocols in VS clinical management is broad, diverse, low certainty, and low quality. This in part reflects a heterogeneous disease, although variability in treatment philosophies may also influence local decision making. Key areas for future study include the clinical utility of advanced imaging techniques and head-to-head comparisons of imaging protocols for patients in common initial VS management pathways (eg, observation, resection, or stereotactic radiosurgery). The full guideline can be seen online at https://www.cns.org/guidelines/treatment-adults-vestibular-schwannoma/5-role-of-imaging-in-management-of-patients-with-v

Abstract Purpose: Monitoring disease progression in patients with high-grade gliomas (HGG) is challenging due to treatment-related changes in imaging and the requirement for neurosurgical intervention to obtain diagnostic tissue. DNA junctions in HGG often amplify oncogenes, making these DNA fragments potentially more abundant in blood than monoallelic mutations. In this study, we piloted a cell-free DNA approach for disease detection in the plasma of patients with HGG by leveraging patient-specific DNA junctions associated with oncogene amplifications. Experimental Design: Whole-genome sequencing of grade 3 or 4 isocitrate dehydrogenase–mutant or wild-type astrocytomas was utilized to identify amplified junctions. Individualized qPCR assays were developed using patient-specific primers designed for the amplified junction. ctDNA levels containing these junctions were measured in patient plasma samples. Results: Unique amplified junctions were evaluated by individualized semi-qPCR assays in presurgical plasma of 18 patients, 15 with tumor-associated focal amplifications and three without tumor-associated focal amplifications. high copy-number junctions were robustly detected in the plasma of 14 of 15 (93.3%) patients with amplified junctions and none of the controls. Changes in junction abundance correlated with disease trajectory in serial plasma samples from five patients, including increased abundance of amplified junctions preceding radiographic disease progression. Conclusions: In patients with grade 3 or 4 astrocytomas who had tumor-associated amplifications, patient-specific amplified junctions were successfully detected in assayed plasma from most patients. Longitudinal analysis of plasma samples correlated with disease trajectory, including cytoreduction and progression.

Abstract Background While serial sampling of glioma tissue is rarely performed prior to recurrence, cerebrospinal fluid (CSF) is an underutilized longitudinal source of candidate glioma biomarkers for understanding therapeutic impacts. However, the impact of key variables to consider in longitudinal CSF samples for monitoring biomarker discovery, including anatomical location and post-surgical changes, remains unknown. Methods Aptamer-based proteomics was performed on 147 CSF samples from 74 patients; 71 of whom had grade 2–4 astrocytomas or grade 2–3 oligodendrogliomas. This included pre- versus post-resection intracranial CSF samples obtained at early (1–16 days; n = 20 patients) or delayed (86–153 days; n = 11 patients) time points for patients with glioma. Paired lumbar versus intracranial glioma CSF samples were also obtained (n = 14 patients). Results Significant differences were identified in the CSF proteome between lumbar, subarachnoid, and ventricular CSF in patients with gliomas. Importantly, we found that resection had a significant, evolving longitudinal impact on the CSF proteome, with distinct sets of proteins present at different time points since resection. Our analysis of serial intracranial CSF samples suggests the early potential for disease monitoring and evaluation of pharmacodynamic impact of targeted therapies, such as bevacizumab and immunotherapies. Conclusions The intracranial glioma CSF proteome serves as a rich and dynamic reservoir of potential biomarkers that can be used to evaluate the effects of resection and other therapies over time. All data within this study, including detailed individual clinical annotations, are shared as a resource for the neuro-oncology community to collectively address these unanswered questions and further understand glioma biology through CSF proteomics.

Abstract Purpose: Current methods for glioma response assessment are limited. This study aimed to assess the technical and clinical feasibility of molecular profiling using longitudinal intracranial cerebrospinal fluid (CSF) from patients with gliomas. Experimental Design: Adults with gliomas underwent longitudinal intracranial CSF collection via Ommaya reservoirs or ventriculoperitoneal shunts. Cell-free DNA (cfDNA) was extracted and analyzed using PredicineCARE for cancer variant profiling and/or PredicineSCORE for low-pass whole-genome sequencing. Results: Five patients (two females and three males; median age, 40 years; range, 32–64 years) underwent longitudinal intracranial CSF collection via Ommaya reservoirs (n = 4) or ventriculoperitoneal shunts (n = 1). In total, 47 CSF samples were obtained (median volume, 4.00 mL; 0.5–5 mL). Forty-one samples (87.2%) yielded sufficient cfDNA for testing. Patient-specific tumor-associated variant allelic frequencies (VAF), and thus tumor fraction, decreased in pre- versus postchemoradiation samples, including through pseudoprogression. These also increased with radiographic progression in three patients, although identifying the time of definitive disease progression from MRIs was a significant limitation. In two patients with isocitrate dehydrogenase (IDH)–mutant gliomas, decreasing IDH1 VAF after resection and chemoradiation correlated with decreased CSF D-2-hydroxyglutarate levels (0.64× and 0.62×, respectively, for the first patient and 0.01× and 0.07× for the other patient), although D-2-hydroxyglutarate and IDH1 VAF were not concordant in one patient thereafter. Moreover, the copy-number burden decreased below the limit of quantification during treatment and increased above the limit at progression. Conclusions: Longitudinal intracranial CSF cfDNA can be obtained in patients with gliomas during their disease course. However, before deploying this technique, numerous questions and challenges should be answered.

Abstract Improved response assessment methods are needed for patients with gliomas. Intracranial cerebrospinal fluid (CSF) is longitudinally accessible and provides an abundance source of candidate biomarkers, such as cell-free DNA (cfDNA), for disease monitoring. To evaluate the clinical feasibility of molecular profiling from longitudinal intracranial CSF, CSF was acquired from patients with CSF access devices, including Ommaya reservoirs and ventriculoperitoneal shunts. cfDNA was extracted and analyzed via PredicineCARE (Next Generation sequencing) or PredicineSCORE (low pass whole genome sequencing). Five patients (2 females, 3 males; median age: 40 years, range 32-64 years) underwent longitudinal intracranial CSF collection via Ommaya reservoirs (n=4) or VP shunt (n=1). In total, forty-eight CSF samples were obtained (median volume: 4.00 mL; 0.5-5 mL), with 39 samples (81.3%) yielding sufficient cfDNA for variant profiling. Our initial findings suggest that tumor fraction increased by 6.28x, 2.87x, and 8.31x with radiographic progression in three patients. Tumor fraction decreased by 0.08x and 0.04x in two patients with paired immediate pre-versus-post chemoradiation samples. Despite ongoing pseudoprogression in one patient, tumor fraction decreased to unmeasurable levels from a post-resection baseline of 0.26. Patient-specific tumor-associated variant allelic frequencies (VAFs), including TP53, PTEN, TERT, and CDKN2A/B, decreased within individual patients after resection and chemoradiation. In two patients with isocitrate dehydrogenase (IDH) mutant gliomas, decreasing IDH1 VAF after resection and chemoradiation correlated with decreased CSF D-2-hydroxyglutarate (D-2-HG) levels (0.64x and 0.62x, respectively, for the first patient, and 0.01x and 0.07x for the other patient). Both CSF IDH1 VAF and CSF D-2-HG increased a patient who had radiographic progression (2.56x and 9.21x, respectively). Moreover, CNB decreased below the limit of quantification during treatment and increased above the limit at progression. In conclusion, longitudinal CSF cfDNA can feasibly be obtained via CSF access devices in patients with gliomas during their disease course toward evaluating candidate monitoring biomarkers.

Abstract While serial sampling of glioma tissue is rarely performed before recurrence, cerebrospinal fluid (CSF) can be acquired serially to evaluate candidate monitoring and pharmacodynamic biomarkers in patients with gliomas. However, the impact of key variables to consider in longitudinal CSF, including anatomical location and post-surgical changes, remains unknown. To that end, pre- versus post-resection intracranial CSF samples from patients with gliomas were obtained at early (1-16 days; n=20) or delayed (86-153 days; n=11) timepoints, as well as lumbar-versus-intracranial glioma CSF samples (n=14). Using aptamer-based proteomics, we identified significant differences in the glioma CSF proteome between lumbar, subarachnoid, and ventricular CSF. Indeed, intracranial CSF in paired lumbar/intracranial samples had nearly 1600 unique aptamers, regardless of which intracranial location was compared to the paired lumbar CSF, including in enrichment style analyses that evaluated the overlap between protein states. Importantly, resection had a significant, evolving longitudinal impact on the CSF proteome, with subsets of proteins associated with early versus delayed post-resection changes, many of which were enriched for inflammatory-related pathways. Interestingly, despite increased contamination from surgical debris, enrichment for plasma-associated proteins decreased with resection (FDR: 0.000), suggesting that a portion of the baseline glioma panel could be derived from plasma-originating analytes due to blood-brain barrier disruption. Despite these challenges, our data still revealed preliminary candidate monitoring biomarkers, such as brevican, that increased with progression (example patient: fold-change of 3.58x and 2.08x through lomustine and bevacizumab, respectively), but not pseudoprogression (Fold change less than 1.5). Serial intracranial CSF samples suggested the early potential for disease monitoring and evaluation of pharmacodynamic impact of targeted therapies, including bevacizumab and pembrolizumab. In conclusion, our available data to date suggest that the intracranial glioma CSF proteome provides an abundant and evolving source of candidate biomarkers to longitudinally discern the impact of resection and systemic treatments.