Preservation of cranial nerve function in large and giant trigeminal schwannoma resection

Acta Neurochirurgica (2024) 166:198

Trigeminal schwannomas (TSs) are intracranial tumors that can cause significant brainstem compression. TS resection can be challenging because of the risk of new neurologic and cranial nerve deficits, especially with large (≥ 3 cm) or giant (≥ 4 cm) TSs. As prior surgical series include TSs of all sizes, we herein present our clinical experience treating large and giant TSs via microsurgical resection.

Methods This was a retrospective, single-surgeon case series of adult patients with large or giant TSs treated with microsurgery in 2012–2023.

Results Seven patients underwent microsurgical resection for TSs (1 large, 6 giant; 4 males; mean age 39 ± 14 years). Tumors were classified as type M (middle fossa in the interdural space; 1 case, 14%), type ME (middle fossa with extracranial extension; 3 cases, 43%), type MP (middle and posterior fossae; 2 cases, 29%), or type MPE (middle/posterior fossae and extracranial space; 1 case, 14%). Six patients were treated with a frontotemporal approach (combined with transmastoid craniotomy in the same sitting in one patient and a delayed transmaxillary approach in another), and one patient was treated using an orbitofrontotemporal approach. Gross total resection was achieved in 5 cases (2 near-total resections). Five patients had preoperative facial numbness, and 6 had immediate postoperative facial numbness, including two with worsened or new symptoms. Two patients (28%) demonstrated new non-trigeminal cranial nerve deficits over mean follow-up of 22 months. Overall, 80% of patients with preoperative facial numbness and 83% with facial numbness at any point experienced improvement or resolution during their postoperative course. All patients with preoperative or new postoperative non-trigeminal tumor-related cranial nerve deficits (4/4) experienced improvement or resolution on follow-up. One patient experienced tumor recurrence that has been managed conservatively.

Conclusions Microsurgical resection of large or giant TSs can be performed with low morbidity and excellent long-term cranial nerve function.

Preoperative Versus Postoperative Radiosurgery of Brain Metastases: A Meta-Analysis

World Neurosurg. (2024) 182:35-41

OBJECTIVE: While postoperative resection cavity radiosurgery (post-SRS) is an accepted treatment paradigm for brain metastasis (BM) patients who undergo surgical resection, there is emerging interest in preoperative radiosurgery (preSRS) followed by surgical resection as an alternative treatment paradigm. Here, we performed a meta-analysis of the available literature on this matter.

METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, a search of all studies evaluating pre-SRS and postSRS was completed. Local recurrence (LR), overall survival (OS), radiation necrosis (RN), and leptomeningeal disease (LMD) were evaluated from the available data. Moderator analysis and pooled effect sizes were performed using a proportional meta-analysis with R using the metafor package. Statistics are presented as mean [95% confidence interval].

RESULTS: We identified 6 pre-SRS and 33 post-SRS studies with comparable tumor volume (4.5-17.6 cm3 ). There were significant differences in the pooled estimates of LR and LMD, favoring pre-SRS over post-SRS. Pooled aggregate for LR was 11.0% [4.9-13.7] and 17.5% [15.1-19.9] for pre- and post-SRS studies (P [ 0.014). Similarly, pooled estimates of LMD favored pre-SRS, 4.4% [2.6-6.2], relative to post-SRS, 12.3% [8.9-15.7] (P [ 0.019). In contrast, no significant differences were found in terms of RN and OS. Pooled estimates for RN were 6.4% [3.1-9.6] and 8.9% [6.3-11.6] for pre- and post-SRS studies (P [ 0.393), respectively. Pooled estimates for OS were 60.2% [55.8-64.6] and 60.5% [56.9-64.0] for pre- and post-SRS studies (P [ 0.974).

CONCLUSIONS: This meta-analysis supports further exploration of pre-SRS as a strategy for the treatment of BM.

Safety of brainstem safe entry zones: comparison of microsurgical outcomes associated with superficial, exophytic, and deep brainstem cavernous malformations

J Neurosurg 139:113–123, 2023

Safe entry zones (SEZs) enable safe tissue transgression to lesions beneath the brainstem surface. However, evidence for the safety of SEZs is scarce and is based on anatomical studies, case reports, and small series.

METHODS A cohort of 154 patients who underwent microsurgical brainstem cavernous malformation (BSCM) treatment during a 23-year period and who had preoperative MR images and intraoperative photographs or videos was retrospectively examined. This study assessed the safety of SEZs for access to deep BSCMs, preoperative MRI to predict BSCM surface proximity, and the relationships between BSCM subtype, surgical approach, and SEZs. Lesions were characterized as exophytic, superficial, or deep on the basis of preoperative MRI and intraoperative inspection. Outcomes were scored as good (modified Rankin Scale [mRS] score ≤ 2) or poor (mRS score > 2) and relative outcomes as stable/ improved or worse relative to baseline (± 1 point).

RESULTS Resections included 34 (22%) in the midbrain, 102 (66%) in the pons, and 18 (12%) in the medulla. Of those, 23 (15%) were exophytic, 57 (37%) were superficial, and 74 (48%) were deep. Established SEZs were used for 97% (n = 72) of deep lesions; the preferred SEZ associated with its subtype was used for 91% (n = 67). MR images accurately depicted exophytic BSCMs that did not require SEZ approaches (sensitivity, 96%) but overestimated the proximity of lesions superficial to brainstem surfaces (specificity, 67%), resulting in unanticipated SEZ use. Final neurological outcomes were good in 80% of patients with follow-up data (119/149), and relative outcomes were stable/improved in 93% (139/149). Outcomes for patients with brainstem transgression through an SEZ did not differ from outcomes for patients with superficial or exophytic lesions that did not require SEZ use (final mRS score ≤ 2 in 72% of all patients with deep lesions vs 82% of all patients with superficial or exophytic lesions [p = 0.10]). Among patients with follow-up, the rates of permanent new cranial nerve deficits in patients with deep BSCMs and superficial or exophytic BSCMs were 21% and 20%, respectively (p = 0.81), with no significant change in overall cranial nerve deficit (0 and −1, p = 0.65).

CONCLUSIONS Neurological outcomes for patients with deep BSCMs were equivalent to those for superficial or exophytic BSCMs, validating the safety of SEZs for deep BSCMs. Preoperative T1-weighted MR images overestimated the lesion’s surface proximity, necessitating detailed knowledge of SEZs and readiness to use them in cases of radiologicalmicrosurgical discordance. Most patients achieved favorable outcomes despite the transgression of eloquent brainstem tissue in and around SEZs.

Predictive factors for post operative seizures following meningioma resection in patients without preoperative seizures: a multicenter retrospective analysis

Acta Neurochirurgica (2023) 165:1333–1343

Meningiomas are the most common primary brain tumor and represent 35% of all intracranial neoplasms. However, in the early post-operative period approximate 3–5% of patients experience an acute symptomatic seizure. Establishing risk factors for postoperative seizures will identify those patients without preoperative seizures at greatest risk of postoperative seizures and may guide antiseizure medications (ASMs) management.

Methods Adult seizure naïve patients who underwent primary resection of a World Health Organization (WHO) Grade 1–3 meningioma at the three Mayo Clinic Campuses between 2012–2022 were retrospectively reviewed. Multivariate regression analyses were used to identify radiological, surgical, and management features with the development of new-onset seizures in patients undergoing meningioma resection.

Results Of 113 seizure naïve patients undergoing meningioma resection 11 (9.7%) experienced a new-onset post-operative seizure. Tumor volume ≥ 25 cm 3 (Odds Ratio (OR) 5.223, 95% Confidence Interval (CI) 1.546 – 17.650, p = 0.008) and cerebral convexity meningiomas (OR 4.742, 95% CI 1.255 – 14.336, p = 0.016) were most associated with new onset postoperative seizures in multivariate analysis. ASMs and corticosteroid therapies did not display a significant difference among those with and without a new onset postoperative seizure.

Conclusion In the current study, a larger tumor volume (≥ 25 cm3 ) and/or convexity meningiomas predicted the development of new onset post-operative seizures. Those who present with these factors should be counseled for their increased risk of new onset post-operative seizures and may benefit from prophylactic ASMs therapy.

Surgery of Insular Diffuse Gliomas—Part 2: Probabilistic Cortico-Subcortical Atlas of Critical Eloquent Brain Structures and Probabilistic Resection Map During Transcortical Awake Resection

Neurosurgery 89:579–590, 2021

Insular diffuse glioma surgery is challenging, and tools to help surgical planning could improve the benefit-to-risk ratio.

OBJECTIVE: To provide a probabilistic resection map and frequency atlases of critical eloquent regions of insular diffuse gliomas based on our surgical experience.

METHODS: We computed cortico-subcortical “eloquent” anatomic sites identified intraoperatively by direct electrical stimulations during transcortical awake resection of insular diffuse gliomas in adults.

RESULTS: From 61 insular diffuse gliomas (39 left, 22 right; all left hemispheric dominance for language), we provided a frequency atlas of eloquence of the opercula (left/right; pars orbitalis: 0%/5.0%; pars triangularis: l5.6%/4.5%; pars opercularis: 37.8%/27.3%; precentral gyrus: 97.3%/95.4%; postcentral and supramarginal gyri: 75.0%/57.1%; temporal pole and superior temporal gyrus: 13.3%/0%), which tailored the transcortical approach (frontal operculum to reach the antero-superior insula, temporal operculum to reach the inferior insula, parietal operculum to reach the posterior insula). We provided a frequency atlas of eloquence identifying the subcortical functional boundaries (36.1% pyramidal pathways, 50.8% inferior fronto-occipital fasciculus, 13.1% arcuate and superior longitudinal fasciculi complex, 3.3% somatosensory pathways, 8.2% caudate and lentiform nuclei). Vascular boundaries and increasing errors during testing limited the resection in 8.2% and 11.5% of cases, respectively. We provided a probabilistic 3-dimensional atlas of resectability.

CONCLUSION: Functional mapping under awake conditions has to be performed intraoperatively in each patient to guide surgical approach and resection of insular diffuse gliomas in right and left hemispheres. Frequency atlases of opercula eloquence and of subcortical eloquent anatomic boundaries, and probabilistic 3-dimensional atlas of resectability could guide neurosurgeons.

Surgery of Insular Diffuse Gliomas—Part 1: Transcortical Awake Resection Is Safe and Independently Improves Overall Survival

Neurosurgery 89:565–578, 2021

Insular diffuse glioma resection is at risk of vascular injury and of postoperative new neurocognitive deficits.

OBJECTIVE: To assess safety and efficacy of surgical management of insular diffuse gliomas.

METHODS: Observational, retrospective, single-institution cohort analysis (2005-2019) of 149 adult patients surgically treated for an insular diffuse glioma: transcortical awake resection with intraoperative functional mapping (awake resection subgroup, n = 61), transcortical asleep resection without functional mapping (asleep resection subgroup, n = 50), and stereotactic biopsy (biopsy subgroup, n = 38). All cases were histopathologically assessed according to the 2016World Health Organization classification and cIMPACTNOW update 3.

RESULTS: Following awake resection, 3/61 patients had permanent motor deficit, seizure control rates improved (89% vs 69% preoperatively, P = .034), and neurocognitive performance improved from 5% to 24% in tested domains, despite adjuvant oncological treatments. Resection rates were higher in the awake resection subgroup (median 94%) than in the asleep resection subgroup (median 46%; P < .001). There was more gross total resection (25% vs 12%) and less partial resection (34% vs 80%) in the awake resection subgroup than in the asleep resection subgroup (P< .001). Karnofsky Performance Status score <70 (adjusted hazard ratio [aHR] 2.74, P = .031), awake resection (aHR 0.21, P = .031), isocitrate dehydrogenase (IDH)-mutant grade 2 astrocytoma (aHR 5.17, P = .003), IDHmutant grade 3 astrocytoma (aHR 6.11, P < .001), IDH-mutant grade 4 astrocytoma (aHR 13.36, P = .008), and IDH-wild-type glioblastoma (aHR 21.84, P < .001) were independent predictors of overall survival.

CONCLUSION:Awake surgery preserving the brain connectivity is safe, allows larger resections for insular diffuse gliomas than asleep resection, and positively impacts overall survival.

Surgery versus radiosurgery for facial nerve schwannoma

J Neurosurg 135:542–553, 2021

Intracranial facial nerve schwannomas (FNS) requiring treatment are frequently recommended for surgery or stereotactic radiosurgery (SRS). The objective of this study was to compare facial nerve function outcomes between these two interventions for FNS via a systematic review and meta-analysis.

METHODS A search of the Ovid EMBASE, PubMed, SCOPUS, and Cochrane databases from inception to July 2019 was conducted following PRISMA guidelines. Articles were screened against prespecified criteria. Facial nerve out- comes were classified as improved, stabilized, or worsened by last follow-up. Incidence was pooled by random-effects meta-analysis of proportions.

RESULTS Thirty-three articles with a pooled cohort of 519 patients with FNS satisfied all criteria. Twenty-five articles described operative outcomes in 407 (78%) patients; 10 articles reported SRS outcomes in 112 (22%). In the surgical cohort, facial nerve function improved in 23% (95% CI 15%–32%), stabilized in 41% (95% CI 32%–50%), and worsened in 30% (95% CI 21%–40%). In the SRS cohort, facial nerve function was improved in 20% (95% CI 9%–34%), stable in 66% (95% CI 54%–78%), and worsened in 9% (95% CI 3%–16%). Compared with SRS, microsurgery was associated with a significantly lower incidence of stable facial nerve function (p < 0.01) and a significantly higher incidence of wors- ened facial nerve function (p < 0.01). Tumor progression and complication rates were comparable. Outcome certainty assessments were very low to moderate for all parameters.

CONCLUSIONS Unfavorable facial nerve function outcomes are associated with surgical treatment of intracranial FNS, whereas stable facial nerve function outcomes are associated with SRS. Therefore, SRS should be recommended to patients with FNS who require treatment, and surgery should be reserved for patients with another indication, such as decompression of the brainstem. Further study is required to definitively optimize and validate management strategies for these rare skull base tumors.

Spetzler-Martin Grade III Arteriovenous Malformations: A Comparison of Modified and Supplemented Spetzler-Martin Grading Systems

Neurosurgery 88:1103–1110, 2021

The modified Spetzler-Martin (SM) grading system proposes that grade III arteriovenous malformation (AVM) subtypes are associated with variable microsurgical risks, with small AVMs (III−) having lower risk and medium/eloquent AVMs (III+) having higher risk. Adding patient age and AVM bleeding status and compactness to the SM grade produces a score – the supplemented SM (Supp-SM) grade – to more accurately assess preoperative risk.

OBJECTIVE: To compare the predictive power of the modified SMand Supp-SM grades for risk assessment in patients with grade III AVMs.

METHODS: Patients with SM grade III AVMs treated between 2011 and 2018were retrospectively reviewed. Good outcomes were defined as modified Rankin Scale (mRS) scores ≤ 2 or unchanged/improved mRS scores (pre- vs postsurgery).

RESULTS: Of 102 patients with SM grade III AVMs, 59% had grade III− and 24% had grade III+ AVMs. Supp SM grade 6 and grade 7 AVMs accounted for 44% and 24%, respectively. Overall, 33% of patients worsened but outcomes did not significantly differ by SM III subtype. Neurological outcomes were associated with Supp-SM grade, with proportions of patients with worsening increasing from 0% with Supp-SM grade 4 AVMs to 54% with Supp-SM grade 7 AVMs. Analyses of factors associated with neurological worsening identified age > 60 yr and Supp-SM grade 7 as significant.

CONCLUSION: Supp-SM grades were more predictive of microsurgical outcomes than modified SM grades for grade III AVMs, with a hard cutoff for acceptable surgical risk at Supp-SM grade 6. Supp-SM grading is a better decision-making tool than subtyping with the modified SM scale.

 

Anatomical multifocal high-grade glioma resection

Acta Neurochirurgica (2021) 163:953–957

If an awake surgery is somehow not available for gliomas at the language area, understanding the anatomy and well designed surgical strategy are important.

Method We present a case with left hemispheric multifocal high-grade gliomas located deeply at the left temporal pole, the Wernicke’s area, and mesial temporal region. Because the patient could not endure the awake surgery and obtain practicable functional magnetic resonance imaging (MRI) for eloquent cortex evaluation, we removed the lesions following the anatomical resection strategy guided by diffusion tensor imaging (DTI).

Conclusion This case demonstrates the value of DTI and the importance of anatomical resection strategies in glioma surgeries.

Is supratotal resection achievable in low-grade gliomas? Feasibility, putative factors, safety, and functional outcome

J Neurosurg 132:1692–1705, 2020

Surgery for low-grade gliomas (LGGs) aims to achieve maximal tumor removal and maintenance of patients’ functional integrity. Because extent of resection is one of the factors affecting the natural history of LGGs, surgery could be extended further than total resection toward a supratotal resection, beyond tumor borders detectable on FLAIR imaging. Supratotal resection is highly debated, mainly due to a lack of evidence of its feasibility and safety. The authors explored the intraoperative feasibility of supratotal resection and its short- and long-term impact on functional integrity in a large cohort of patients. The role of some putative factors in the achievement of supratotal resection was also studied.

METHODS Four hundred forty-nine patients with a presumptive radiological diagnosis of LGG consecutively admitted to the neurosurgical oncology service at the University of Milan over a 5-year period were enrolled. In all patients, a policy was adopted to perform surgery according to functional boundaries, aimed at achieving a supratotal resection whenever possible, without any patient or tumor a priori selection. Feasibility, general safety, and tumor or patient putative factors possibly affecting the achievement of a supratotal resection were analyzed. Postsurgical patient functional performance was evaluated in five cognitive domains (memory, language, praxis, executive functions, and fluid intelligence) using a detailed neuropsychological evaluation and quality of life (QOL) examination.

RESULTS Total resection was feasible in 40.8% of patients, and supratotal resection in 32.3%. The achievement of a supratotal versus total resection was independent of age, sex, education, tumor volume, deep extension, location, handedness, appearance of tumor border, vicinity to eloquent sites, surgical mapping time, or surgical tools applied. Supratotal resection was associated with a long clinical history and histological grade II, suggesting that reshaping of brain networks occurred. Although a consistent amount of apparently MRI-normal brain was removed with this approach, the procedure was safe and did not carry additional risk to the patient, as demonstrated by detailed neuropsychological evaluation and QOL examination. This approach also improved seizure control.

CONCLUSIONS Supratotal resection is feasible and safe in routine clinical practice. These results show that a long clinical history may be the main factor associated with its achievement.

5-Aminolevulinic Acid and Contrast-Enhanced Ultrasound: The Combination of the 2 Techniques to Optimize the Extent of Resection in Glioblastoma Surgery

Neurosurgery 86:E529–E540, 2020

The survival benefit in maximizing resection in glioblastomas (GBMs) has been demonstrated by numerous studies. The true limit of infiltration of GBMs has been an overwhelming obstacle, and several technological advances have been introduced to improve the identification of residual tumors.

OBJECTIVE: To evaluate whether the integration of 5-aminolevulinic acid (5-ALA) with microbubble contrast-enhanced ultrasound (CEUS) improves residual tumor identification and has an impact on the extent of resection (EOR), overall survival (OS), and progressionfree survival (PFS).

METHODS: A total of 230 GBM procedures were retrospectively studied. Cases were stratified according to the surgical procedure into 4 groups: 5-ALA- and CEUS-guided surgeries, 5-ALA-guided surgeries, CEUS-guided surgeries, and conventional microsurgical procedures.

RESULTS: Patients undergoing conventional microsurgical procedures showed the worst EORs compared to the assisted techniques (5-ALA and CEUS procedures). Both 5-ALA and CEUS techniques improved the EOR compared to conventional microsurgical procedures. However, their combination gave the best results in terms of the EOR (P = .0003). The median EOR% and the number of supramarginal resections are hence superior in the 5-ALA + CEUS + group compared to the others; this observation had consequences on PFS and OS in our series.

CONCLUSION: In terms of the EOR, the best results can be achieved through a combination of both techniques,where the 5-ALA-guided procedure is followed by a final survey with CEUS. Compared with other intraoperative imaging techniques, CEUS is a real-time, readily repeatable, safe, and inexpensive technique that provides valuable information to the surgeon before, during, and after resection.

Resection of gliomas deemed inoperable by neurosurgeons based on preoperative imaging studies

J Neurosurg 129:567–575, 2018

Maximal safe resection is a primary objective in the management of gliomas. Despite this objective, surgeons and referring physicians may, on the basis of radiological studies alone, assume a glioma to be unresectable. Because imaging studies, including functional MRI, may not localize brain functions (such as language) with high fidelity, this simplistic approach may exclude some patients from what could be a safe resection. Intraoperative direct electrical stimulation (DES) allows for the accurate localization of functional areas, thereby enabling maximal resection of tumors, including those that may appear inoperable based solely on radiological studies. In this paper the authors describe the extent of resection (EOR) and functional outcomes following resections of tumors deemed inoperable by referring physicians and neurosurgeons.

METHODS The authors retrospectively examined the cases of 58 adult patients who underwent glioma resection within 6 months of undergoing a brain biopsy of the same lesion at an outside hospital. All patients exhibited unifocal supratentorial disease and preoperative Karnofsky Performance Scale scores ≥ 70. The EOR and 6-month functional outcomes for this population were characterized.

RESULTS Intraoperative DES mapping was performed on 96.6% (56 of 58) of patients. Nearly half of the patients (46.6%, 27 of 58) underwent an awake surgical procedure with DES. Overall, the mean EOR was 87.6% ± 13.6% (range 39.0%–100%). Gross-total resection (resection of more than 99% of the preoperative tumor volume) was achieved in 29.3% (17 of 58) of patients. Subtotal resection (95%–99% resection) and partial resection (PR; < 95% resection) were achieved in 12.1% (7 of 58) and 58.6% (34 of 58) of patients, respectively. Of the cases that involved PR, the mean EOR was 79.4% ± 12.2%. Six months after surgery, no patient was found to have a new postoperative neurological deficit. The majority of patients (89.7%, 52 of 58) were free of neurological deficits both pre- and postoperatively. The remainder of patients exhibited either residual but stable deficits (5.2%, 3 of 58) or complete correction of preoperative deficits (5.2%, 3 of 58).

CONCLUSIONS The use of DES enabled maximal safe resections of gliomas deemed inoperable by referring neurosurgeons. With rare exceptions, tumor resectability cannot be determined solely by radiological studies.

Method for temporal keyhole lobectomies in resection of low- and high-grade gliomas

J Neurosurg 128:1388–1395, 2018

The purpose of this study was to describe a method of resecting temporal gliomas through a keyhole lobectomy and to share the results of using this technique.

METHODS The authors performed a retrospective review of data obtained in all patients in whom the senior author performed resection of temporal gliomas between 2012 and 2015. The authors describe their technique for resecting dominant and nondominant gliomas, using both awake and asleep keyhole craniotomy techniques.

RESULTS Fifty-two patients were included in the study. Twenty-six patients (50%) had not received prior surgery. Seventeen patients (33%) were diagnosed with WHO Grade II/III tumors, and 35 patients (67%) were diagnosed with a glioblastoma. Thirty tumors were left sided (58%). Thirty procedures (58%) were performed while the patient was awake. The median extent of resection was 95%, and at least 90% of the tumor was resected in 35 cases (67%). Five of 49 patients (10%) with clinical follow-up experienced permanent deficits, including 3 patients (6%) with hydrocephalus requiring placement of a ventriculoperitoneal shunt and 2 patients (4%) with weakness. Three patients experienced early postoperative anomia, but no patients had a new speech deficit at clinical follow-up.

CONCLUSIONS The authors provide their experience using a keyhole lobectomy for resecting temporal gliomas. Their data demonstrate the feasibility of using less invasive techniques to safely and aggressively treat these tumors.

 

Frontal Keyhole Craniotomy for Resection of Low- and High-Grade Gliomas

Neurosurgery 82:388–396, 2018

Minimally invasive techniques are increasingly being used to access intraaxial brain lesions.

OBJECTIVE: To describe a method of resecting frontal gliomas through a keyhole craniotomy and share the results with these techniques.

METHODS: We performed a retrospective review of data obtained on all patients undergoing resection of frontal gliomas by the senior author between 2012 and 2015.We describe our technique for resecting dominant and nondominant gliomas utilizing both awake and asleep keyhole craniotomy techniques.

RESULTS: After excluding 1 patient who received a biopsy only, 48 patients were included in the study. Twenty-nine patients (60%) had not received prior surgery. Twenty-six patients (54%) were diagnosed with WHO grade II/III tumors, and 22 patients (46%) were diagnosedwith glioblastoma. Twenty-five cases (52%)were performed awake.At least 90% of the tumor was resected in 35 cases (73%). Three of 43 patients with clinical follow-up experienced permanent deficits.

CONCLUSION: We provide our experience in using keyhole craniotomies for resecting frontal gliomas. Our data demonstrate the feasibility of using minimally invasive techniques to safely and aggressively treat these tumors.

Comparing Preoperative With Postoperative Stereotactic Radiosurgery for Resectable Brain Metastases: A Multi-institutional Analysis

Motor function after stereotactic radiosurgery for brain metastases in the region of the motor cortex

Neurosurgery 79:279–285, 2016

Stereotactic radiosurgery (SRS) is an increasingly common modality used with surgery for resectable brain metastases (BM).

OBJECTIVE: To present a multi-institutional retrospective comparison of outcomes and toxicities of preoperative SRS (Pre-SRS) and postoperative SRS (Post-SRS).

METHODS: We reviewed the records of patients who underwent resection of BM and either Pre-SRS or Post-SRS alone between 2005 and 2013 at 2 institutions. Pre-SRS used a dose-reduction strategy based on tumor size, with planned resection within 48 hours. Cumulative incidence with competing risks was used to determine estimated rates.

RESULTS: A total of 180 patients underwent surgical resection for 189 BM: 66 (36.7%) underwent Pre-SRS and 114 (63.3%) underwent Post-SRS. Baseline patient characteristics were balanced except for higher rates of performance status 0 (62.1% vs 28.9%, P , .001) and primary breast cancer (27.2% vs 10.5%, P = .010) for Pre-SRS. Pre-SRS had lower median planning target volume margin (0 mm vs 2 mm) and peripheral dose (14.5 Gy vs 18 Gy), but similar gross tumor volume (8.3 mL vs 9.2 mL, P = .85). The median imaging follow-up period was 24.6 months for alive patients. Multivariable analyses revealed no difference between groups for overall survival (P = .1), local recurrence (P = .24), and distant brain recurrence (P = .75). Post-SRS was associated with significantly higher rates of leptomeningeal disease (2 years: 16.6% vs 3.2%, P = .010) and symptomatic radiation necrosis (2 years: 16.4% vs 4.9%, P = .010).

CONCLUSION: Pre-SRS and Post-SRS for resected BM provide similarly favorable rates of local recurrence, distant brain recurrence, and overall survival, but with significantly lower rates of symptomatic radiation necrosis and leptomeningeal disease in the Pre-SRS cohort. A prospective clinical trial comparing these treatment approaches is warranted.

Comparing Preoperative With Postoperative Stereotactic Radiosurgery for Resectable Brain Metastases

Motor function after stereotactic radiosurgery for brain metastases in the region of the motor cortex

Neurosurgery 79:279–285, 2016

Stereotactic radiosurgery (SRS) is an increasingly common modality used with surgery for resectable brain metastases (BM).

OBJECTIVE: To present a multi-institutional retrospective comparison of outcomes and toxicities of preoperative SRS (Pre-SRS) and postoperative SRS (Post-SRS).

METHODS: We reviewed the records of patients who underwent resection of BM and either Pre-SRS or Post-SRS alone between 2005 and 2013 at 2 institutions. Pre-SRS used a dose-reduction strategy based on tumor size, with planned resection within 48 hours. Cumulative incidence with competing risks was used to determine estimated rates.

RESULTS: A total of 180 patients underwent surgical resection for 189 BM: 66 (36.7%) underwent Pre-SRS and 114 (63.3%) underwent Post-SRS. Baseline patient characteristics were balanced except for higher rates of performance status 0 (62.1% vs 28.9%, P < .001) and primary breast cancer (27.2% vs 10.5%, P = .010) for Pre-SRS. Pre-SRS had lower median planning target volume margin (0 mm vs 2 mm) and peripheral dose (14.5 Gy vs 18 Gy), but similar gross tumor volume (8.3 mL vs 9.2 mL, P = .85). The median imaging follow-up period was 24.6 months for alive patients. Multivariable analyses revealed no difference between groups for overall survival (P = .1), local recurrence (P = .24), and distant brain recurrence (P = .75). Post-SRS was associated with significantly higher rates of leptomeningeal disease (2 years: 16.6% vs 3.2%, P = .010) and symptomatic radiation necrosis (2 years: 16.4% vs 4.9%, P = .010).

CONCLUSION: Pre-SRS and Post-SRS for resected BM provide similarly favorable rates of local recurrence, distant brain recurrence, and overall survival, but with significantly lower rates of symptomatic radiation necrosis and leptomeningeal disease in the Pre-SRS cohort. A prospective clinical trial comparing these treatment approaches is warranted.

Topographical Risk Factor Analysis of New Neurological Deficits Following Precentral Gyrus Resection

Topographical Risk Factor Analysis of New Neurological Deficits Following Precentral Gyrus Resection

Neurosurgery 76:714–720, 2015

Precentral gyrus resections (PGRs) have been regarded as excessively hazardous interventions because of the risk of postoperative major neurological complications.

OBJECTIVE: To evaluate the neurological deterioration that follows PGRs and to assess the topographical risk factors associated with these morbidities.

METHODS: We reviewed 33 consecutive patients who experienced pharmacologically intractable epilepsy and underwent PGR with intraoperative cortical stimulation and mapping while under awake anesthesia. The etiological diagnoses were brain neoplasm in 26 patients (78.8%), cortical lesion in 4 (12.1%), and no lesion in 3 (9.1%). The mean follow-up period was 62.6 months (range, 12-146 months). All topographical analyses of the resected quadrant area were performed based on postoperative magnetic resonance images.

RESULTS: After PGR, 22 patients (66.7%) experienced neurological worsening, including 5 permanent deficits (15.2%) and 17 transient deficits (51.5%). Permanent deficits included 2 instances of weakness, 1 dysarthria, 1 dysesthesia, and 1 fine-movement disturbance of the hand. While the neurological risk for anterior lower quadrant PGR was 20.0% (1/5), the risk for posterior upper quadrant PGR was 100.0% (10/10). The anterior upper and posterior lower quadrant PGR caused neurological deteriorations in 60.0% (6/10) and 62.5% (5/8) of the patients, respectively. In a multivariate analysis, PGR of the posterior and upper quadrant sections were significant risk factors for post-PGR neurological deteriorations (P = .022 and 0.030, respectively).

CONCLUSION: The posterior upper quadrant of the precentral gyrus was vulnerable to post-resective neurological impairment.

The utility of preoperative diffusion tensor imaging in the surgical management of brainstem cavernous malformations

The utility of preoperative diffusion tensor imaging in the surgical management of brainstem cavernous malformations

J Neurosurg 122:653–662, 2015

Resection of brainstem cavernous malformations (BSCMs) may reduce the risk of stepwise neurological deterioration secondary to hemorrhage, but the morbidity of surgery remains high. Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) are neuroimaging techniques that may assist in the complex surgical planning necessary for these lesions. The authors evaluate the utility of preoperative DTI and DTT in the surgical management of BSCMs and their correlation with functional outcome.

Methods A retrospective review was conducted to identify patients who underwent resection of a BSCM between 2007 and 2012. All patients had preoperative DTI/DTT studies and a minimum of 6 months of clinical and radiographic follow-up. Five major fiber tracts were evaluated preoperatively using the DTI/DTT protocol: 1) corticospinal tract, 2) medial lemniscus and medial longitudinal fasciculus, 3) inferior cerebellar peduncle, 4) middle cerebellar peduncle, and 5) superior cerebellar peduncle. Scores were applied according to the degree of distortion seen, and the sum of scores was used for analysis. Functional outcomes were measured at hospital admission, discharge, and last clinic visit using modified Rankin Scale (mRS) scores.

Results Eleven patients who underwent resection of a BSCM and preoperative DTI were identified. The mean age at presentation was 49 years, with a male-to-female ratio of 1.75:1. Cranial nerve deficit was the most common presenting symptom (81.8%), followed by cerebellar signs or gait/balance difficulties (54.5%) and hemibody anesthesia (27.2%). The majority of the lesions were located within the pons (54.5%). The mean diameter and estimated volume of lesions were 1.21 cm and 1.93 cm3, respectively. Using DTI and DTT, 9 patients (82%) were found to have involvement of 2 or more major fiber tracts; the corticospinal tract and medial lemniscus/medial longitudinal fasciculus were the most commonly affected. In 2 patients with BSCMs without pial presentation, DTI/DTT findings were important in the selection of the surgical approach. In 2 other patients, the results from preoperative DTI/DTT were important for selection of brainstem entry zones. All 11 patients underwent gross-total resection of their BSCMs. After a mean postoperative follow-up duration of 32.04 months, all 11 patients had excellent or good outcome (mRS Score 0–3) at the time of last outpatient clinic evaluation. DTI score did not correlate with long-term outcome.

Conclusions Preoperative DTI and DTT should be considered in the resection of symptomatic BSCMs. These imaging studies may influence the selection of surgical approach or brainstem entry zones, especially in deep-seated lesions without pial or ependymal presentation. DTI/DTT findings may allow for more aggressive management of lesions previously considered surgically inaccessible. Preoperative DTI/DTT changes do not appear to correlate with functional postoperative outcome in long-term follow-up.

Indocyanine Green Angiography in the Surgical Management of Cerebral Arteriovenous Malformations

Indocyanine Green Angiography in the Surgical Management of Cerebral Arteriovenous Malformations

Operative Neurosurgery 10:246–251, 2014

Indocyanine green (ICG) angiography is commonly used to map the vascular configuration of cerebral arteriovenous malformations (AVMs) during resection.

OBJECTIVE: To determine whether ICG improves rates of resection and clinical outcomes.

METHODS: A retrospective chart review was done for all patients undergoing resection of an AVM by the senior author (R.F.S.) between 2007 and 2011. Operative reports, hospital records, and radiographic imaging were used to determine the use of ICG, the incidence of residual disease, and clinical outcomes.

RESULTS: A total of 130 cases (56 ICG, 74 non-ICG) were identified. Average AVM grade (2.2 vs 2.4) and size (2.7 vs 2.7 cm) were similar between the ICG and non-ICG groups, respectively. ICG was more often used when the AVM nidus was close to the cortical surface (71.4% vs 17.6%; P = .001) or lobar (82.1% vs 54.1%; P = .008). Eighteen patients (13.8%) were noted to have residual disease. Reoperation rates and change in modified Rankin Scale score were not different between the 2 groups (12.5% vs 14.9%, P = .8; 0.6 vs 0.4, P = .17). There were no ICG-attributable complications.

CONCLUSION: ICG videoangiography is a quick and safe method of intraoperatively mapping the angioarchitecture of superficial AVMs, but it is less helpful for deep-seated lesions. This modality alone does not improve the identification of residual disease or clinical outcomes. Surgeon experience with extensive study of preoperative vascular imaging is paramount to achieving acceptable clinical outcomes. Formal angiography remains the gold standard for the evaluation of AVM obliteration.

Risk factor analysis of the development of new neurological deficits following supplementary motor area resection

Supplementary motor area

J Neurosurg 119:7–14, 2013

Supplementary motor area (SMA) resection often induces postoperative contralateral hemiparesis or speech disturbance. This study was performed to assess the neurological impairments that often follow SMA resection and to assess the risk factors associated with these postoperative deficits.

Methods. The records for patients who had undergone SMA resection for pharmacologically intractable epilepsy between 1994 and 2010 were gleaned from an epilepsy surgery database and retrospectively reviewed in this study.

Results. Forty-three patients with pharmacologically intractable epilepsy underwent SMA resection with intraoperative cortical stimulation and mapping while under awake anesthesia. The mean patient age was 31.7 years (range 15–63 years), and the mean duration and frequency of seizures were 10.4 years (range 0.1–30 years) and 14.6 per month (range 0.1–150 per month), respectively. Pathological examination of the brain revealed cortical dysplasia in 18 patients (41.9%), tumors in 16 patients (37.2%), and other lesions in 9 patients (20.9%). The mean duration of the follow-up period was 84.0 months (range 24–169 months). After SMA resection, 23 patients (53.5%) experienced neurological deficits. Three patients (7.0%) experienced permanent deficits, and 20 (46.5%) experienced symptoms that were transient. All permanent deficits involved contralateral weakness, whereas the transient symptoms patients experienced were varied, including contralateral weaknesses in 15, apraxia in 1, sensory disturbances in 1, and dysphasia in 6. Thirteen patients recovered completely within 1 month. Univariate analysis revealed that resection of the SMA proper, a shorter lifetime seizure history (< 10 years), and resection of the cingulate gyrus in addition to the SMA were associated with the development of neurological deficits (p = 0.078, 0.069, and 0.023, respectively). Cingulate gyrus resection was the only risk factor identified on multivariate analysis (p = 0.027, OR 6.530, 95% CI 1.234–34.562).

Conclusions. Resection of the cingulate gyrus in addition to the SMA was significantly associated with the development of postoperative neurological impairment.