Long-term outcomes of CNS WHO grade 2 oligodendroglioma in adult patients: a single-institution experience.

PURPOSE: Oligodendrogliomas (ODGs) are a subtype of diffuse lower-grade gliomas with overall survival of > 10 years. This study aims to analyze long-term outcomes and identify prognostic factors in patients with WHO grade 2 ODG. METHODS: We retrospectively reviewed 138 adult patients diagnosed with 1p/19q co-deleted ODG who underwent surgical resection or biopsy between 1994 and 2021, analyzing clinical data, treatment details, and outcomes. Progression-free survival (PFS) and overall survival (OS) were evaluated using Kaplan-Meier analysis. Univariate and multivariate Cox regression analyses were utilized to identify significant prognostic factors. RESULTS: In the gross total resection (GTR) group, 63 (45.7%) underwent observation and 5 (3.6%) received postoperative treatment; in the non-GTR group, 37 (26.8%) were observed and 33 (23.9%) received postoperative treatment. The median PFS and OS were 6.8 and 18.4 years, respectively. Between adjuvant treatment and observation, there was no significant difference in PFS or OS. However, GTR or STR with less than 10% residual tumor exhibited significantly better PFS and OS compared to PR or biopsy (p = 0.022 and 0.032, respectively). Multivariate analysis revealed that contrast enhancement on MRI was associated with worse PFS (HR = 2.36, p < 0.001) and OS (HR = 5.89, p = 0.001). And the presence of seizures at presentation was associated with improved OS (HR = 0.28, p = 0.006). CONCLUSION: This study underscores favorable long-term outcomes for patients with 1p/19q co-deleted ODG WHO grade 2. Our findings indicate that the EOR plays a crucial role as a significant prognostic factor in enhancing PFS and OS outcomes in WHO grade 2 ODG.

Endoscopic transorbital approach to the petrous apex: is orbital rim removal worthwhile for the exposure? An anatomical study with illustrative case.

OBJECTIVE: The endoscopic transorbital approach (ETOA) has been demonstrated to be a feasible ventral route to the petrous apex. Yet, it has been pointed to as a deep and narrow corridor for anterior petrosectomy; particularly, medialization of the instruments can become an issue when targeting the petroclival area. To overcome this limitation, an ETOA with orbital rim removal (ETOA-OR) has been suggested, but not de facto compared, with a transorbital approach without removal of the rim. This addition could augment the surgical exposure and freedom of movement when accessing the petrous apex area. METHODS: Five human cadaveric heads (10 sides) were dissected. First, anterior petrosectomy was performed via a conventional ETOA (without orbital rim removal). Second, en bloc removal of the orbital rim was performed, with enlargement of the orbital craniectomy and, subsequently, further drilling of the medial petrous apex. Qualitative and quantitative comparisons are provided. An illustrative surgical case is also shown. RESULTS: The transorbital route allowed the authors to perform an anterior petrosectomy in all specimens. The landmarks of bone removal are superposed onto those in the transcranial route. The ETOA-OR increased the volume of craniectomy (from 4.0 mL to 5.5 mL), the lateromedial angulation, and superoinferior angulation of the instruments within the petrous area. Thus, this approach improved the exposure of the medial petroclival area, allowing for an augmented petrosectomy (from 1.4 mL to 2.0 mL, 39.5% increase) and for increased maneuverability, both in the petrous area (from 44.1 cm2 to 76.5 cm2, 73.3% increase) and in the posterior fossa (from 20.2 cm2 to 52.0 cm2, 158% increase). The ETOA-OR was also pragmatically applied to treat a recurrent petroclival meningioma. Complete removal was achieved, the abducens nerve palsy improved, and the trigeminal neuralgia decreased in severity, yet still required medication. CONCLUSIONS: The authors provide the first formal anatomical comparison between the transorbital approach with preservation of the orbital rim and a transorbital approach with removal of the rim to access the petrous apex. In addition, an illustrative case is used as a proof of concept and feasibility. According to the authors' data, the ETOA-OR significantly improves surgical exposure and the surgeon's comfort in this deep region. The bony defect can be reconstructed to avoid cosmetic deformities, maintaining the minimally disruptive concept of transorbital surgery.

Measuring statistics-induced entanglement entropy with a Hong-Ou-Mandel interferometer.

Despite its ubiquity in quantum computation and quantum information, a universally applicable definition of quantum entanglement remains elusive. The challenge is further accentuated when entanglement is associated with other key themes, e.g., quantum interference and quantum statistics. Here, we introduce two novel motifs that characterize the interplay of entanglement and quantum statistics: an 'entanglement pointer' and a 'statistics-induced entanglement entropy'. The two provide a quantitative description of the statistics-induced entanglement: (i) they are finite only in the presence of quantum entanglement underlined by quantum statistics and (ii) their explicit form depends on the quantum statistics of the particles (e.g., fermions, bosons, and anyons). We have experimentally implemented these ideas by employing an electronic Hong-Ou-Mandel interferometer fed by two highly diluted electron beams in an integer quantum Hall platform. Performing measurements of auto-correlation and cross-correlation of current fluctuations of the scattered beams (following 'collisions'), we quantify the statistics-induced entanglement by experimentally accessing the entanglement pointer and the statistics-induced entanglement entropy. Our theoretical and experimental approaches pave the way to study entanglement in various correlated platforms, e.g., those involving anyonic Abelian and non-Abelian states.

Surgical Strategy for Petroclival Meningioma-Related Trigeminal Neuralgia: The Role of Porus Trigeminus Opening.

OBJECTIVE: Petroclival meningiomas invade Meckel's cave through the porus trigeminus, leading to secondary trigeminal neuralgia. Microsurgery and stereotactic radiosurgery (SRS) are the typical treatment options. This study investigated symptom control, outcomes, and surgical strategies for PC meningioma-induced TN. METHODS: We retrospectively analyzed 28 TN patients with PC meningiomas who underwent microsurgical nerve decompression between January 2021 and February 2023. In all patients undergoing a transpetrosal approach, the porus trigeminus was opened to enable the removal of the entire tumor within Meckel's cave. Clinical outcomes were assessed using the Barrow Neurologic Institute (BNI) pain intensity scale. Risk factors for poor TN outcomes and poor facial numbness were analyzed. RESULTS: Among 28 patients, 21 (75%) underwent the transpetrosal approach, 5 (17.9%) underwent the retrosigmoid approach, and 2 (7.1%) underwent the Dolenc approach. Following microsurgery, 23 patients (82.1%) experienced TN relief without further medication (BNI I or II). TN recurrence occurred in 2 patients (7.1%), and 3 patients (10.7%) did not achieve TN relief. Cavernous sinus invasion was significantly correlated with poor TN outcomes (P = 0.047). A history of previous SRS (P = 0.011) and upper clivus type tumor (P = 0.018) were significantly associated with poor facial numbness. CONCLUSIONS: Microsurgical nerve decompression is effective in improving BNI scores in patients with TN associated with PC meningiomas. Considering the results of our study, the opening of the porus trigeminus can be considered as a suggested procedure in the treatment of PC meningiomas, especially in cases accompanied by TN.

Generative AI in glioma: Ensuring diversity in training image phenotypes to improve diagnostic performance for IDH mutation prediction.

BACKGROUND: This study evaluated whether generative artificial intelligence (AI)-based augmentation (GAA) can provide diverse and realistic imaging phenotypes and improve deep learning-based classification of isocitrate dehydrogenase (IDH) type in glioma compared with neuroradiologists. METHODS: For model development, 565 patients (346 IDH-wildtype, 219 IDH-mutant) with paired contrast-enhanced T1 and FLAIR MRI scans were collected from tertiary hospitals and The Cancer Imaging Archive. Performance was tested on internal (119, 78 IDH-wildtype, 41 IDH-mutant [IDH1 and 2]) and external test sets (108, 72 IDH-wildtype, 36 IDH-mutant). GAA was developed using a score-based diffusion model and ResNet50 classifier. The optimal GAA was selected in comparison with the null model. Two neuroradiologists (R1, R2) assessed realism, diversity of imaging phenotypes, and predicted IDH mutation. The performance of a classifier trained with optimal GAA was compared with that of neuroradiologists using the area under the receiver operating characteristics curve (AUC). The effect of tumor size and contrast enhancement on GAA performance was tested. RESULTS: Generated images demonstrated realism (Turing's test: 47.5-50.5%) and diversity indicating IDH type. Optimal GAA was achieved with augmentation with 110 000 generated slices (AUC: 0.938). The classifier trained with optimal GAA demonstrated significantly higher AUC values than neuroradiologists in both the internal (R1, P = .003; R2, P < .001) and external test sets (R1, P < .01; R2, P < .001). GAA with large-sized tumors or predominant enhancement showed comparable performance to optimal GAA (internal test: AUC 0.956 and 0.922; external test: 0.810 and 0.749). CONCLUSIONS: The application of generative AI with realistic and diverse images provided better diagnostic performance than neuroradiologists for predicting IDH type in glioma.

Feasibility and efficacy of endoscopic transorbital optic canal decompression for meningiomas causing compressive optic neuropathy.

OBJECTIVE: The endoscopic transorbital approach (ETOA) and transorbital anterior clinoidectomy have been suggested as novel procedures through which to reach the superolateral compartments of the orbit, allowing optic canal decompression. However, there is limited literature describing the technical details and surgical outcomes of these procedures. In this study, the authors aimed to analyze the feasibility and efficacy of endoscopic transorbital decompression of the optic canal through anterior clinoidectomy for compressive optic neuropathic lesions. METHODS: Between 2016 and 2022, the authors performed ETOA for compressive optic neuropathic lesions in 14 patients. All these patients underwent transorbital anterior clinoidectomy through the surgically defined "intraorbital clinoidal triangle," which is composed of the roof of the superior orbital fissure, the medial margin of the optic canal, the medial border of the superior orbital fissure, and the optic strut. Demographic data, tumor characteristics, pre- and postoperative imaging, pre- and postoperative visual examinations, and surgical outcomes were retrospectively reviewed. RESULTS: The mean age at the time of ETOA was 53.3 years (range 41-64 years), and the mean follow-up was 16.8 months (range 6.7-51.4 months). The inclusion criterion in this study was having a meningioma (14 patients). In the preoperative visual function examination, 7 patients with a meningioma showed progressive visual impairment. After endoscopic transorbital optic canal decompression, visual function improved in 5 patients, remained unchanged in 8 patients, and worsened in 1 patient. No new-onset neurological deficit was associated with ETOA and anterior clinoidectomy in any patients. CONCLUSIONS: Endoscopic transorbital decompression of the optic canal with extradural anterior clinoidectomy is a safe and feasible technique that avoids significant injury to the clinoidal internal carotid artery and surrounding neurovascular structures.

Prediction of pseudoprogression in post-treatment glioblastoma using dynamic susceptibility contrast-derived oxygenation and microvascular transit time heterogeneity measures.

OBJECTIVES: To evaluate the added value of MR dynamic susceptibility contrast (DSC)-perfusion-weighted imaging (PWI)-derived tumour microvascular and oxygenation information with cerebral blood volume (CBV) to distinguish pseudoprogression from true progression (TP) in post-treatment glioblastoma. METHODS: This retrospective single-institution study included patients with isocitrate dehydrogenase (IDH) wild-type glioblastoma and a newly developed or enlarging measurable contrast-enhancing mass within 12 weeks after concurrent chemoradiotherapy. CBV, capillary transit time heterogeneity (CTH), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2) were obtained from DSC-PWI. Predictors were selected using univariable logistic regression, and performance was measured with adjusted diagnostic odds with tumour volume and area under the curve (AUC) of receiver operating characteristics analysis. RESULTS: A total of 103 patients were included (mean age, 59.6 years; 59 women), with 67 cases of TP and 36 cases of pseudoprogression. Pseudoprogression exhibited higher CTH (4.0 vs. 3.4, p = .019) and higher OEF (12.7 vs. 10.7, p = .014) than TP, but a similar CBV (1.48 vs. 1.53, p = .13) and CMRO2 (7.7 vs. 7.3s, p = .598). Independent of tumour volume, both high CTH (adjusted odds ratio [OR] 1.52; 95% confidence interval [CI]: 1.11-2.09, p = .009) and high OEF (adjusted OR 1.17; 95% CI:1.03-1.33, p = .016) were predictors of pseudoprogression. The combination of CTH, OEF, and CBV yielded higher diagnostic performance (AUC 0.71) than CBV alone (AUC 0.65). CONCLUSION: High intratumoural capillary transit heterogeneity and high oxygen extraction fraction derived from DSC-PWI have enhanced the diagnostic value of CBV in pseudoprogression of post-treatment IDH-wild type glioblastoma. CLINICAL RELEVANCE STATEMENT: In the early post-treatment stage of glioblastoma, pseudoprogression exhibited both high oxygen extraction fraction and high capillary transit heterogeneity and these dynamic susceptibility contrast-perfusion weighted imaging derived parameters have added value in cerebral blood volume-based noninvasive differentiation of pseudoprogression from true progression. KEY POINTS: • Capillary transit time heterogeneity and oxygen extraction fraction can be measured noninvasively through processing of dynamic susceptibility contrast imaging. • Pseudoprogression exhibited higher capillary transit time heterogeneity and higher oxygen extraction fraction than true progression. • A combination of cerebral blood volume, capillary transit time heterogeneity, and oxygen extraction fraction yielded the highest diagnostic performance (area under the curve 0.71).

Partitioning of diluted anyons reveals their braiding statistics.

Correlations of partitioned particles carry essential information about their quantumness1. Partitioning full beams of charged particles leads to current fluctuations, with their autocorrelation (namely, shot noise) revealing the particles' charge2,3. This is not the case when a highly diluted beam is partitioned. Bosons or fermions will exhibit particle antibunching (owing to their sparsity and discreteness)4-6. However, when diluted anyons, such as quasiparticles in fractional quantum Hall states, are partitioned in a narrow constriction, their autocorrelation reveals an essential aspect of their quantum exchange statistics: their braiding phase7. Here we describe detailed measurements of weakly partitioned, highly diluted, one-dimension-like edge modes of the one-third filling fractional quantum Hall state. The measured autocorrelation agrees with our theory of braiding anyons in the time domain (instead of braiding in space); with a braiding phase of 2θ = 2π/3, without any fitting parameters. Our work offers a relatively straightforward and simple method to observe the braiding statistics of exotic anyonic states, such as non-abelian states8, without resorting to complex interference experiments9.

Defining subventricular zone involvement to predict the survival of patients in isocitrate dehydrogenase-wild type glioblastoma: validation in a prospective registry.

OBJECTIVES: The prognostic value of subventricular zone distance (SVD) is unclear because of different definitions and lack of evaluation of clinical survival models. The aim of this study was to define SVD and evaluate its prognostic value in a survival nomogram for glioblastoma. METHODS: This retrospective study included 158 (SVD biomarker) from historical glioblastoma patients and 187 (survival modeling) with IDH-wild type glioblastoma from a prospective registry (NCT02619890). SVD was assessed by two radiologists: definition 1, the distance between the tumor edge to subventricular zone (SVZ); definition 2, the distance between the tumor centroid to SVZ; definition 3, enhancement at the ventricular wall. The associations between SVD and overall survival (OS) were evaluated using multivariable Cox proportional hazards regression analysis. Performance of an updated SVD survival model was compared with that of the Radiation Therapy Oncology Group (RTOG) 0525 nomogram. RESULTS: SVD according to both definition 1 (hazard ratio [HR]: 0.97, 95% CI: 0.94-0.99; p = .011) and definition 2 (HR: 0.96, 0.94-0.98, p < .001) was adversely associated with OS. Definition 1 was adversely associated with PFS (HR: 0.96, 0.94-0.99, p = .008) and showed the highest reproducibility (intraclass correlation coefficient, 0.90). The SVD-updated model showed similar to better performance than the RTOG model for predicting OS of up to 3 years (AUC: 0.735-0.738 vs. 0.687-0.708), with higher time-dependent specificity for 1-year (89.9% vs. 70.6%) and 3-year OS (93.3% vs. 80.0%). CONCLUSION: SVZ distance is an independent adverse prognostic factor in patients with IDH-wild type glioblastoma. Updating the survival model with SVZ provides better time-dependent specificity and reproducibility. KEY POINTS: • Subventricular zone distance (SVD) measurement from tumor edge showed high reproducibility. • Longer SVD was independently associated with longer overall survival. • Adding SVD improved time-dependent specificity for survival model in a prospective registry.

Corrigendum: Vestibular schwannoma associated with neurofibromatosis type 2: Clinical course following stereotactic radiosurgery.

[This corrects the article DOI: 10.3389/fonc.2022.996186.].

Anaplastic Meningioma: Clinical Characteristics, Prognostic Factors and Survival Outcome.

BACKGROUND: Anaplastic meningioma is very rare and is generally known to have a poor prognosis. However, due to its rarity, the relationship between clinical prognosis and prognostic factors is not clear. We analyzed the prognostic factors influencing survival outcomes of patients with anaplastic meningioma. Moreover, we analyzed on the progression pattern and the response to treatment about anaplastic meningioma. METHODS: Retrospective review of 48 patients with diagnosis of World Health Organization (WHO) grade 3 meningioma was performed. According to diagnosis type, primary anaplastic meningioma was included in 28 cases and secondary anaplastic meningioma in 20 cases. Gross total resection was performed in 36 patients (75.0%), and 32 patients (66.7%) received adjuvant radiotherapy after tumor resection with confirmed WHO grade 3 meningioma. Kaplan-Meier survival curve and Cox proportional hazards modeling were used for outcome analysis. RESULTS: The median progression-free survival (PFS) and overall survival (OS) were 13.9 months (95% confidence interval [CI], 8.8 to 19.1) and 56.9 months (95% CI, 24.1 to 89.7), respectively. Adjuvant radiotherapy was a robust prognostic factor for PFS and OS. Extent of resection and diagnosis type which appeared to be significant prognostic factors in univariate analysis were failed to prove statistical significance in multivariate analysis. CONCLUSION: Adjuvant radiotherapy is an essential treatment arm in patients with anaplastic meningiomas. Stereotactic radiosurgery seems to play an important role as a salvage treatment. But chemotherapy seems to have limited efficacy. Because of the disseminated nature of the disease, further investigations to improve survival outcome are needed.

Differences in stromal component of chordoma are associated with contrast enhancement in MRI and differential gene expression in RNA sequencing.

Chordoma is a malignant bone neoplasm demonstrating notochordal differentiation and it frequently involves axial skeleton. Most of chordomas are conventional type with varying amount of myxoid stroma. Previously known prognostic factors for conventional chordoma are not specific for chordoma: old age, metastasis, tumor extent, and respectability. Here, we aimed to investigate the histologic, radiologic, and transcriptomic differences in conventional chordoma based on the stromal component. A total of 45 patients diagnosed with conventional chordoma were selected between May 2011 and March 2020 from a single institution. Electronic medical records, pathology slides, and pretreatment magnetic resonance imaging (MRI) scans were reviewed. Of the 45 patients, ten cases (4 stroma-rich and 6 stroma-poor tumor) were selected for RNA sequencing, and available cases in the remainder were used for measuring target gene mRNA expression with qPCR for validation. Differential gene expression and gene set analysis were performed. Based on histologic evaluation, there were 25 (55.6%) stroma-rich and 20 (44.4%) stroma-poor cases. No clinical differences were found between the two groups. Radiologically, stroma-rich chordomas showed significant signal enhancement on MRI (72.4% vs 27.6%, p = 0.002). Upregulated genes in stroma-rich chordomas were cartilage-, collagen/extracellular matrix-, and tumor metastasis/progression-associated genes. Contrarily, tumor suppressor genes were downregulated in stroma-rich chordomas. On survival analysis, Kaplan-Meier plot was separated that showed inferior outcome of stroma-rich group, although statistically insignificant. In conclusion, the abundant stromal component of conventional chordoma enhanced well on MRI and possibly contributed to the biological aggressiveness that supported by transcriptomic characteristics. Further extensive investigation regarding radiologic-pathologic-transcriptomic correlation in conventional chordoma in a larger cohort could verify additional clinical significance.

Vestibular schwannoma associated with neurofibromatosis type 2: Clinical course following stereotactic radiosurgery.

Objective: A lack of understanding of the clinical course of neurofibromatosis type 2 (NF2)-associated vestibular schwannoma (VS) often complicates the decision-making in terms of optimal timing and mode of treatment. We investigated the outcomes of stereotactic radiosurgery (SRS) in this population. Methods: We retrospectively analyzed NF2 patients treated with Gamma-Knife SRS for VS in our tertiary referral center. A total of 41 treated lesions from 33 patients were collected with a follow-up period of 69.1 (45.0-104.8) months. We reviewed the treatment history, hearing function, and other treatment-related morbidities in individual cases. We also analyzed pre- and post-treatment tumor volumes via imaging studies. Longitudinal volumetric analyses were conducted for the tumor volume response of the 41 treated lesions following SRS. The growth pattern of 22 unirradiated lesions during an observation period of 83.4 (61.1-120.4) months was separately evaluated. Results: Most treated lesions showed effective tumor control up to 85% at 60 months after SRS, whereas unirradiated lesions progressed with a relative volume increase of 14.0% (7.8-27.0) per year during the observation period. Twelve (29%) cases showed pseudoprogression with significant volume expansion in the early follow-up period, which practically reduced the rate of tumor control to 57% at 24 months. Among the patients with serviceable hearing, two (20%) cases lost the hearing function on the treated side during the early follow-up period within 24 months. Conclusions: Progressive NF2-associated VS can be adequately controlled by SRS but the short-term effects of this treatment are not highly advantageous in terms of preserving hearing function. SRS treatment candidates should therefore be carefully selected.

Combined petrosal approach for a huge retroclival meningioma preserving the cranial nerves.

Surgery for petroclival meningioma is challenging because cranial nerve preservation during tumor removal can be very complex. For small- to medium-sized tumors, the anatomical relationship between tumor and neurovascular structures can be assessed before surgery. However, in large tumors, cranial nerves usually cannot be seen in preoperative images. The authors present a case of a 65-year-old woman who presented with gait disturbance and hearing loss and was diagnosed with huge retroclival meningioma involving the cavernous sinus, Meckel's cave, and internal acoustic meatus. In this video, they explain the radiographical, anatomical, and surgical considerations and demonstrate the surgical technique. The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21221.

Sphero-Conical Modeling for the Estimation of Very Long Baseline Interferometry Invariant Point.

A geodetic reference frame is a fundamental element in geoinformation fields such as autonomous navigation and digital twins. The international terrestrial reference frame is established and maintained using several space-geodetic techniques, including very long baseline interferometry (VLBI) and satellite laser ranging (SLR). For several decades, geodesists have been devoted to connecting these two sensors at a site (local tie). The reference point of the VLBI antenna and SLR telescope, called invariant point (IVP), should be precisely determined to connect these two solutions. We developed an innovative integrated model to estimate the IVP, which is composed of spherical and conical models, depending on the rotational axis. In this model, all target points in 3D spaces were directly connected to the IVP; thus, the stability and robustness of the system were secured. Furthermore, all inherent errors in the coordinates were predicted by applying the total least-squares approach.

Development of 3-dimensional printed simulation surgical training models for endoscopic endonasal and transorbital surgery.

Background: Endoscopic skull base surgery (ESBS) is complex, requiring methodical and unremitting surgical training. Herein, we describe the development and evaluation of a novel three-dimensional (3D) printed simulation model for ESBS. We further validate the efficacy of this model as educational support in neurosurgical training. Methods: A patient-specific 3D printed simulation model using living human imaging data was established and evaluated in a task-based hands-on dissection program. Endoscopic endonasal and transorbital procedures were simulated on the model by neurosurgeons and otorhinolaryngology surgeons of varying experience. All procedures were recorded using a high-definition camera coupled with digital video recorder system. The participants were asked to complete a post-procedure questionnaire to validate the efficacy of the model. Results: Fourteen experts and 22 trainees participated in simulations, and the 32 participants completed the post-procedure survey. The anatomical realism was scored as 4.0/5.0. The participants rated the model as helpful in hand-eye coordination training (4.7/5.0) and improving surgical skills (4.6/5.0) for ESBS. All participants believed that the model was useful as educational support for trainees (4.7 [ ± 0.5]). However, the color (3.6/5.0) and soft tissue feedback parameters (2.8/5) scored low. Conclusion: This study shows that high-resolution 3D printed skull base models for ESBS can be generated with high anatomical accuracy and acceptable haptic feedback. The simulation program of ESBS using this model may be supplemental or provide an alternative training platform to cadaveric dissection.

Thirty-year clinical experience in gamma knife radiosurgery for trigeminal schwannomas.

We aimed to evaluate the radiographic and clinical outcomes after gamma knife radiosurgery (GKRS) for trigeminal schwannomas (TSs). A total of 87 patients who underwent GKRS for TSs between 1990 and 2020 were enrolled. The mean tumor volume was 4.3 cm3. The median prescribed dose for the margins of the tumor was 13 Gy. The median follow-up duration was 64.3 months (range 12.0-311.5 months). The overall local tumor control rate was 90%, and the symptom response rate was 93%. The response rate for each symptom was 88% for facial pain, 97% for facial sensory change, and 86% for cranial nerve deficits. Nineteen (22%) patients showed transient swelling, which had regressed at the time of the last follow-up. Cystic tumors were associated with transient swelling (p = 0.04). A tumor volume of < 2.7 cm3 was associated with local tumor control in univariable analysis. Transient swelling was associated with symptom control failure in both univariable and multivariable analyses (p = 0.04, odds ratio 14.538). GKRS is an effective treatment for TSs, both for local control and symptom control.

Pedicled frontal periosteal rescue flap via eyebrow incision for skull base reconstruction (SevEN-002).

PURPOSE: Cerebrospinal fluid (CSF) leakage is one of the major complications after endoscopic endonasal surgery. The reconstructive nasoseptal flap is widely used to repair CSF leakage. However, it could not be utilized in all cases; thus, there was a need for an alternative. We developed a pericranial rescue flap that could cover both sellar and anterior skull base defects via the endonasal approach. A modified surgical technique that did not violate the frontal sinus and cause cosmetic problems was designed using the pericranial rescue flap. METHODS: We performed 12 cadaveric dissections to investigate the applicability of the lateral pericranial rescue flap. An incision was made, extending from the middle to the lateral part of the eyebrow. The pericranium layer was dissected away from the galea layer, from the supraorbital region towards the frontoparietal region. With endoscopic assistance, the periosteal flap was raised, the flap base was the pericranium layer at the eyebrow incision. After a burr-hole was made in the supraorbital bone, the pericranial flap was inserted via the intradural or extradural pathway. RESULTS: The mean size of the pericranial flap was 11.5 cm × 3.2 cm. It was large enough to cross the midline and cover the dural defects of the anterior skull base, including the sellar region. CONCLUSION: We demonstrated a modified endoscopic technique to repair the anterior skull base defects. This minimally invasive pericranial flap may resolve neurosurgical complications, such as CSF leakage.