Gompel, Jamie J. Van

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.

Summary: The lack of reliable seizure detection remains a significant challenge for epilepsy care. A clinical deep brain stimulation (DBS) system provides constrained ambulatory brain recordings; however, limited data exist on the use of DBS recordings for seizure detection and lateralization. We present the case of an 18-year-old patient with drug-resistant focal epilepsy, who had seizure detection and lateralization by DBS recordings. Prior stereotactic-EEG, including a thalamus lead, identified independent left orbitofrontal and mesial temporal onset seizures. Notably, low-frequency thalamic ictal power was significantly elevated relative to baseline awake and sleep states. The patient was subsequently implanted with an anterior nucleus of the thalamus DBS system. Postimplantation, low-frequency power-in-band (5.3–10.3 Hz) recordings were initiated. Nursing staff identified four typical clinical seizures during the inpatient DBS recording period. Thalamic DBS trends contained relative peaks that were coincident with each nurse-reported seizure. Peri-ictal power was uniformly maximal ipsilateral to the seizure network. This case demonstrates the feasibility of seizure detection and lateralization by a thalamic DBS system for some individuals, and suggests DBS sensing parameter selection may be guided by thalamic stereotactic EEG. Further research is necessary to assess the generalizability of DBS seizure detection across individuals and diverse seizure networks.

Objective: The pattern, rate, and natural history of bone flap resorption following cranioplasty with frozen, autologous bone flap has not been fully defined. The authors sought to quantify the progression and natural history of bone flap resorption. Methods: Patients who had craniectomy and delayed cranioplasty with stored, frozen bone flap between 2012 and 2022 were included in this study. Results: Ninety patients (63% male) were included, with a median age of 44.8 years (range: 4.2–84.4 y) at the time of autologous bone flap cranioplasty. Delayed, autologous cranioplasty occurred at a median time of 29.5 days (range: 2 d–10 y) from the index craniectomy. The median follow-up was 16.6 months (range: 3.4–85.4 mo). Radiographically quantifiable bone flap resorption occurred in 50 patients (56%). During the follow-up, the average percentage volume loss was 17%, with a nonlinear pattern of resorption. Following delayed, autologous cranioplasty, 11 patients had clinically significant bone flap resorption requiring secondary alloplastic cranioplasty at a median time of 13.8 months (range: 5.9–57.2 mo), with a mean percentage volume loss of 61%. Younger age was a risk factor for bone flap resorption (P < 0.05), whereas active smoking, presence of comorbidities, and number of days of bone flap storage were not risk factors for bone flap resorption. Penalized B-spline regression analysis showed that bone flap resorption followed a nonlinear pattern. Conclusion: Radiographically quantifiable bone flap resorption occurred in about 56% of patients following delayed autologous cranioplasty. Resorption followed a non-linear pattern. Young age is a risk factor for bone flap resorption.

Objective To analyze cases of medial migration of vestibular schwannomas to propose an underlying mechanism. Study Design Retrospective chart review. Patients Ten patients from one institution with sporadic vestibular schwannomas that demonstrated medial migration toward the cerebellopontine angle on serial imaging were reviewed. Interventions Among the 10 patients studied, 8 patients underwent stereotactic radiosurgery and 2 were managed with wait-and-scan. All serial imaging was analyzed throughout follow-up. Main Outcome Measures Volumetric and linear measurements were used to assess vestibular schwannoma growth. The fundal fluid cap length was measured from the most lateral end of the neoplasm within the internal auditory canal to the medial end of the cochlea. Pure tone averages of 0.5, 1, 2, and 3 kHz, word recognition scores, and AAO-HNS hearing class were used to assess levels of hearing loss per patient. Results Tumor growth exhibited a positive correlation with medial migration. Of the 10 patients studied, 9 exhibited tumor volume growth from initial to most recent imaging. Median changes in tumor volumes and fundal fluid cap lengths from initial diagnosis to the most recent imaging regardless of intervention were 130 mm3 (range 1,400–2,970) and 2.8 mm (range 1.8–6.0), respectively. Migration was noted in 4 patients prior to any intervention, in 4 patients postradiosurgery, and in 2 patients before and after radiosurgery. Therefore, half of the tumors studied migrated before an intervention and half migrated postradiosurgery. No correlation of migration and hearing decline was observed. Conclusion Medial migration of vestibular schwannoma is associated with an increase in tumor volume, supporting a “tumor squeeze” mechanism within a conical internal auditory canal toward the wider porus acusticus and cerebellopontine angle.

BACKGROUND The authors applied laser interstitial thermal therapy (LITT) to a recurrent skull base chordoma, which has not been previously described. OBSERVATIONS A 63-year-old man was initially diagnosed with an 8-cm destructive clival chordoma, which was aggressively resected endoscopically but recurred despite multiple operations, proton radiation therapy, and chemotherapy. The patient underwent uncomplicated LITT for a subtemporal mass, which palliated the tumor for 10 months. However, it did not ultimately prevent the need for resection, although it may have delayed the surgery. LESSONS This case study demonstrates the feasibility and safety of LITT in treating these typically surgically challenging tumors. https://thejns.org/doi/10.3171/CASE24534

Objective To compare the utility of intraoperative electrically evoked auditory brainstem response (eABR) and electrically evoked stapedial reflex testing (eSRT) for cochlear nerve integrity monitoring during simultaneous translabyrinthine resection of vestibular schwannoma (VS) and cochlear implantation. Study design Historical cohort study. Setting Tertiary academic referral center. Patients Eleven patients (12 cases) who underwent translabyrinthine tumor resection with simultaneous placement of a standard, unmodified cochlear implant (CI). Intervention A CI placed at the beginning of the operation before tumor resection to facilitate intraoperative cochlear nerve monitoring through a CI-delivered electrical stimulus. Main outcome measure Correlation of intraoperative monitoring outcomes with postoperative CI performance. Results Among the 12 cases (median age, 47 years), eABR waveforms were present at the conclusion of tumor resection in 10, including 6 that achieved open set speech perception. Of the 2 cases with negative eABR, 1 achieved open set speech perception. By contrast, of the 8 cases with a positive eSRT response, 7 achieved open set speech perception. Of the 4 cases with a negative eSRT response, none achieved open set speech perception. The 3 cases that did not receive auditory stimulation included 2 with positive and 1 with negative eABR; all 3 had a negative eSRT response. Conclusions Intraoperative eSRT using an unmodified CI is a promising new method for monitoring the integrity of the cochlear nerve during simultaneous VS resection. eSRT response at the conclusion of tumor resection strongly correlated with CI open set speech capacity. Although still useful, eABR was less reliable at predicting postoperative hearing outcomes in this series.

Abstract Purpose: Craniopharyngiomas are rare parasellar tumors, and papillary craniopharyngiomas (PCP) represent 8-20% of cases. We assessed surgical outcomes of these very rare tumors among patients treated in the last decade. Methods: Retrospective data from the Registry of Adenomas of the Pituitary and Related Disorders (RAPID) were used to evaluate patients with PCP treated between 2011 and 2023 at 14 US-based academic skull base centers. Demographic, imaging, surgical, and outcome variables were analyzed. Results: Ninety-nine patients with PCP were included. Mean age was 51.8±14.7 and 57.6% were male. Most tumors showed mixed cystic/solid components (67.5%), were trans-infundibular (50.0%), and were treated endoscopically (74.5%), with 51.1% demonstrating gross total resection (GTR). Pituitary stalk was preserved in 51.9%. Permanent arginine vasopressin deficiency was seen in 68.8% and was associated with pituitary stalk sacrifice (p=0.02). Cerebrospinal fluid leak was the most common nonendocrine postsurgical, 30-day complication (9.1%), reason for return to the operating room (3.1%), and reason for 90-day readmission (8.1%). Return to the operating room was associated with discharge to a skilled nursing or rehabilitation facility (p=0.0001). Most patients (63.9%) received no adjuvant therapy; GTR was associated with decreased radiotherapy use (p=0.0001). BRAFV600E mutation was detected in 64/69 tumors tested, although only 1 patient was treated with a BRAF inhibitor. Conclusion: To our knowledge, the RAPID consortium enabled the largest real-world clinical information dataset for PCP. Our data can be used as a benchmark for short-term surgical outcomes. Longer-term follow-up studies are needed to understand how to optimize outcomes from each treatment modality.

AbstractObjectiveNeck metastases are a poor prognostic factor in olfactory neuroblastoma (ONB). Pathologic dural invasion (pathDI) may increase the risk of neck metastases due to invasion of dural lymphatics. We aim to evaluate the prognostic value of pathDI in predicting rates of neck metastases and recurrence using a large, multicenter database of ONB patients.Data sourcesRetrospective review of a prospective, multicenter database of electronic health records of all patients who presented with ONB between 2005 and 2021 at nine tertiary academic care centers within North America.Review methodsClinicopathologic features including modified Kadish staging systems, margin status, treatment modalities, Hyams grading, follow‐up time, and survival.ResultsOf 258 ONB patients, 189 patients met the inclusion criteria. The 10‐year neck recurrence‐free survival (neck‐RFS) rates were 85.7% (75.6‒97.3) and 61.8% (47.9‒79.8) for patients without and with pathDI, respectively (p = 0.018). Time‐to‐event multivariable regression analysis found pathDI to have an odds ratios of 9.7 (95% confidence interval [CI] 1.2–80.4, p = 0.04) for neck‐RFS and 9.5 for RFS at any site (95% CI 1.1–83.3, p = 0.04).ConclusionIn multivariable analysis, the presence of pathDI appears to be the strongest predictor of neck recurrence and recurrence at any site. Future studies exploring the benefit of elective neck dissection or radiation for patients with pathDI may impact disease management.

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.