Supracerebellar transtentorial (SCTT) approaches have become a popular option for treatment of a variety of pathologies in the medial and basal temporal and occipital lobes and thalamus. Transtentorial approaches provide numerous advantages over transcortical approaches, including obviating the need to traverse eloquent cortex, not requiring parenchymal retraction, and circumventing critical vascular structures. All of these approaches require a tentorial opening, and numerous techniques for retraction of the incised tentorium have been described, including sutures, fixed retractors, and electrocautery. However, all of these techniques have considerable drawbacks and limitations. The authors describe a novel application of clip retraction of the tentorium to the supracerebellar approaches in which an aneurysm clip is used to suspend the tentorial flap, and an illustrative case is provided. Clip retraction of the tentorium is an efficient, straightforward adaptation of an established technique, typically used for subtemporal approaches, that improves visualization and surgical ergonomics with little risk to nearby venous structures. The authors find this technique particularly useful for the contralateral SCTT approaches.
Jacob F. Baranoski, Ankush Bajaj, Colin J. Przybylowski, Joshua S. Catapano, Fabio A. Frisoli, Michael J. Lang and Michael T. Lawton
Colin J. Przybylowski, Tyler S. Cole, Jacob F. Baranoski, Andrew S. Little, Kris A. Smith and Andrew G. Shetter
The objective of this study was to assess long-term outcomes of facial pain and numbness after radiosurgery for multiple sclerosis (MS)–related trigeminal neuralgia (MS-TN).
The authors conducted a retrospective review of their Gamma Knife radiosurgeries (GKRSs) to identify all patients treated for MS-TN (1998–2014) with at least 3 years of follow-up. Treatment and clinical data were obtained via chart review and mailed or telephone surveys. Pain control was defined as a facial pain score of I–IIIb on the Barrow Neurological Institute (BNI) Facial Pain Intensity Scale. Kaplan-Meier analysis was performed to determine the rates of pain control after index and first salvage GKRS procedures. Patients could have had more than 1 salvage procedure. Pain control rates were based on the number of patients at risk during follow-up.
Of the 50 living patients who underwent GKRS, 42 responded to surveys (31 women [74%], median age 59 years, range 32–76 years). During the initial GKRS, the trigeminal nerve root entry zone was targeted with a single isocenter, using a 4-mm collimator with the 90% isodose line completely covering the trigeminal nerve and the 50% isodose line abutting the surface of the brainstem. The median maximum radiation dose was 85 Gy (range 50–85 Gy). The median follow-up period was 78 months (range 36–226 months). The rate of pain control after the index GKRS (n = 42) was 62%, 29%, 22%, and 13% at 1, 3, 5, and 7 years, respectively. Twenty-eight patients (67%) underwent salvage treatment, including 25 (60%) whose first salvage treatment was GKRS. The rate of pain control after the first salvage GKRS (n = 25) was 84%, 50%, 44%, and 17% at 1, 3, 5, and 7 years, respectively. The rate of pain control after the index GKRS with or without 1 salvage GKRS (n = 33) was 92%, 72%, 52%, 46%, and 17% at 1, 3, 5, 7, and 10 years, respectively. At last follow-up, 9 (21%) of the 42 patients had BNI grade I facial pain, 35 (83%) had achieved pain control, and 4 (10%) had BNI grade IV facial numbness (very bothersome in daily life).
Index GKRS offers good short-term pain control for MS-TN, but long-term pain control is uncommon. If the index GKRS fails, salvage GKRS appears to offer beneficial pain control with low rates of bothersome facial numbness.
Colin J. Przybylowski, Jacob F. Baranoski, Veronica M. So, Jeffrey Wilson and Nader Sanai
The choice of transsylvian versus transcortical corridors for resection of insular gliomas remains controversial. Functional pathway compromise from transcortical transgression and vascular injury during transsylvian dissection are the primary concerns. In this study, data from a single-center experience with both approaches were compared to determine whether one approach was associated with a higher rate of morbidity than the other.
The authors identified 100 consecutive patients who underwent resection of pure insular gliomas at the Barrow Neurological Institute. Volumetric analysis was performed using FLAIR and contrast-enhanced T1-weighted MRI for low- and high-grade gliomas, respectively, for extent of resection (EOR) and diffusion-weighted sequences were used to detect for postoperative ischemia. Step-wise logistic regression analysis was performed to identify predictors of neurological morbidity.
Data from 100 patients with low-grade or high-grade insular gliomas were analyzed. Fifty-two patients (52%) underwent a transsylvian approach, and 48 patients (48%) underwent a transcortical approach. The mean (± SD) EOR was 91.6% ± 12.4% in the transsylvian group and 88.6% ± 14.2% in the transcortical group (p = 0.26). Clinical outcome metrics for the 2 groups were similar. Overall, 13 patients (25%) in the transsylvian group and 10 patients (21%) in the transcortical group had evidence of ischemia on postoperative MR images. For both approaches, high-grade histology was associated with permanent morbidity (p = 0.01). For patients with gliomas located within the superior-posterior quadrant of the insula, development of postoperative ischemia was associated with only the transsylvian approach (46% vs 0%, p = 0.02).
Areas of restricted diffusion are common on postoperative MRI following resection of insular gliomas, but only a minority of these patients develop permanent neurological deficits. Insular glioma patients with high-grade histology may be at particular risk for developing symptomatic postoperative ischemia. Both the transcortical and transsylvian corridors are associated with reasonable morbidity profiles, although gliomas situated within the superior-posterior quadrant of the insula are more safely accessed with a transcortical approach.
Brian J. McHugh, Jacob F. Baranoski, Ajay Malhotra, Alexander O. Vortmeyer, Gordon Sze and Charles C. Duncan
Intracranial infantile hemangiopericytomas (HPCs) are exceedingly rare lesions. Only 11 cases have been previously reported in the literature. As such, little is known about the etiology, long-term prognosis, and optimal treatment paradigm. Clinically, they are consistently less aggressive than those in adults. The authors present the case of a 2-month-old boy with an intracranial HPC, review the available literature, discuss the evolving concepts of what defines an HPC, and offer a potential explanation to how HPC histology might relate to the clinical behavior of these lesions.
Colin J. Przybylowski, Xiaochun Zhao, Jacob F. Baranoski, Leandro Borba Moreira, Sirin Gandhi, Kristina M. Chapple, Kaith K. Almefty, Nader Sanai, Andrew F. Ducruet, Felipe C. Albuquerque, Andrew S. Little and Peter Nakaji
The controversy continues over the clinical utility of preoperative embolization for reducing tumor vascularity of intracranial meningiomas prior to resection. Previous studies comparing embolization and nonembolization patients have not controlled for detailed tumor parameters before assessing outcomes.
The authors reviewed the cases of all patients who underwent resection of a WHO grade I intracranial meningioma at their institution from 2008 to 2016. Propensity score matching was used to generate embolization and nonembolization cohorts of 52 patients each, and a retrospective review of clinical and radiological outcomes was performed.
In total, 52 consecutive patients who underwent embolization (mean follow-up 34.8 ± 31.5 months) were compared to 52 patients who did not undergo embolization (mean follow-up 32.8 ± 28.7 months; p = 0.63). Variables controlled for included patient age (p = 0.82), tumor laterality (p > 0.99), tumor location (p > 0.99), tumor diameter (p = 0.07), tumor invasion into a major dural sinus (p > 0.99), and tumor encasement around the internal carotid artery or middle cerebral artery (p > 0.99). The embolization and nonembolization cohorts did not differ in terms of estimated blood loss during surgery (660.4 ± 637.1 ml vs 509.2 ± 422.0 ml; p = 0.17), Simpson grade IV resection (32.7% vs 25.0%; p = 0.39), perioperative procedural complications (26.9% vs 19.2%; p = 0.35), development of permanent new neurological deficits (5.8% vs 7.7%; p = 0.70), or favorable modified Rankin Scale (mRS) score (a score of 0–2) at last follow-up (96.0% vs 92.3%; p = 0.43), respectively. When comparing the final mRS score to the preoperative mRS score, patients in the embolization group were more likely than patients in the nonembolization group to have an improvement in mRS score (50.0% vs 28.8%; p = 0.03).
After controlling for patient age, tumor size, tumor laterality, tumor location, tumor invasion into a major dural sinus, and tumor encasement of the internal carotid artery or middle cerebral artery, preoperative meningioma embolization intended to decrease tumor vascularity did not improve the surgical outcomes of patients with WHO grade I intracranial meningiomas, but it did lead to a greater chance of clinical improvement compared to patients not treated with embolization.
Alberto Cacciola, Antonio Pontoriero, Giuseppe Iatì, Alfredo Conti, Antonino Germanò, Francesca Granata and Stefano Pergolizzi
Mark W. Youngblood, Daniel Duran, Julio D. Montejo, Chang Li, Sacit Bulent Omay, Koray Özduman, Amar H. Sheth, Amy Y. Zhao, Evgeniya Tyrtova, Danielle F. Miyagishima, Elena I. Fomchenko, Christopher S. Hong, Victoria E. Clark, Maximilien Riche, Matthieu Peyre, Julien Boetto, Sadaf Sohrabi, Sarah Koljaka, Jacob F. Baranoski, James Knight, Hongda Zhu, M. Necmettin Pamir, Timuçin Avşar, Türker Kilic, Johannes Schramm, Marco Timmer, Roland Goldbrunner, Ye Gong, Yaşar Bayri, Nduka Amankulor, Ronald L. Hamilton, Kaya Bilguvar, Irina Tikhonova, Patrick R. Tomak, Anita Huttner, Matthias Simon, Boris Krischek, Michel Kalamarides, E. Zeynep Erson-Omay, Jennifer Moliterno and Murat Günel
Recent large-cohort sequencing studies have investigated the genomic landscape of meningiomas, identifying somatic coding alterations in NF2, SMARCB1, SMARCE1, TRAF7, KLF4, POLR2A, BAP1, and members of the PI3K and Hedgehog signaling pathways. Initial associations between clinical features and genomic subgroups have been described, including location, grade, and histology. However, further investigation using an expanded collection of samples is needed to confirm previous findings, as well as elucidate relationships not evident in smaller discovery cohorts.
Targeted sequencing of established meningioma driver genes was performed on a multiinstitution cohort of 3016 meningiomas for classification into mutually exclusive subgroups. Relevant clinical information was collected for all available cases and correlated with genomic subgroup. Nominal variables were analyzed using Fisher’s exact tests, while ordinal and continuous variables were assessed using Kruskal-Wallis and 1-way ANOVA tests, respectively. Machine-learning approaches were used to predict genomic subgroup based on noninvasive clinical features.
Genomic subgroups were strongly associated with tumor locations, including correlation of HH tumors with midline location, and non-NF2 tumors in anterior skull base regions. NF2 meningiomas were significantly enriched in male patients, while KLF4 and POLR2A mutations were associated with female sex. Among histologies, the results confirmed previously identified relationships, and observed enrichment of microcystic features among “mutation unknown” samples. Additionally, KLF4-mutant meningiomas were associated with larger peritumoral brain edema, while SMARCB1 cases exhibited elevated Ki-67 index. Machine-learning methods revealed that observable, noninvasive patient features were largely predictive of each tumor’s underlying driver mutation.
Using a rigorous and comprehensive approach, this study expands previously described correlations between genomic drivers and clinical features, enhancing our understanding of meningioma pathogenesis, and laying further groundwork for the use of targeted therapies. Importantly, the authors found that noninvasive patient variables exhibited a moderate predictive value of underlying genomic subgroup, which could improve with additional training data. With continued development, this framework may enable selection of appropriate precision medications without the need for invasive sampling procedures.