Hemispherectomy at The Hospital for Sick Children: expanded indications and lessons learned over 35 years.

OBJECTIVE: Functional hemispherectomy is an effective surgical intervention for select patients with drug-resistant epilepsy. The last several decades have seen dramatic evolutions in preoperative evaluation, surgical techniques, and postoperative care. Here, the authors present a retrospective review of the medical records of 146 children who underwent hemispherectomy between 1987 and 2022 at The Hospital for Sick Children, providing a unique overview of the evolution of the procedure and patient outcomes over 35 years. METHODS: The medical records of all children who underwent hemispherectomy at The Hospital for Sick Children between 1987 and 2022 were reviewed. Demographic information, preoperative clinical features, short-term and long-term seizure outcomes, and details regarding postoperative complications were recorded. RESULTS: The seizure outcomes of 146 children were analyzed. There were 68 females and 78 males with a mean age of 5.08 years, 123 of whom demonstrated seizure freedom (Engel class IA) in the short-term postoperative follow-up period and 89 in the long term. The effectiveness of hemispherectomy in achieving long-term seizure control has improved over time (ß = 0.06, p < 0.001). Factors associated with overall seizure freedom included younger age at the time of hemispherectomy and stroke as the etiology of seizures, as well as complete disconnection during the first surgery. Additionally, the etiologies of epilepsy for which hemispherectomy is performed have expanded over time, while complication rates have remained unchanged. CONCLUSIONS: Hemispherectomy is an increasingly effective treatment for certain cases of drug-resistant epilepsy. The etiologies of epilepsy for which hemispherectomy is performed are broadening, with no change in its safety profile. Seizure outcomes are better when the etiology of epilepsy is an ischemic injury, and the most common complication after the procedure is hydrocephalus. These findings reinforce the ongoing use of hemispherectomy as a safe and effective treatment option for certain individuals with drug-resistant epilepsy, support its application to a broader range of etiologies, and highlight areas of future investigation.

The Utility of a "Second-Look" Debridement Following Endonasal Skull Base Surgery in the Pediatric Population.

Background Sinonasal debridement is typically performed in the weeks following endonasal skull base surgery (ESBS). In the pediatric population, this second-look procedure may require general anesthesia; however, there is currently little evidence assessing the benefit of this practice. Methods This was a multicenter retrospective study of pediatric patients (age <18 years) undergoing a planned second-look debridement under general anesthesia following ESBS. Intraoperative findings, interventions performed, and perioperative complications were reviewed. Multivariate regression analysis was performed to identify associations between intraoperative findings and clinical factors. Results We reviewed 69 cases of second-look debridements (age mean 8.6 ± 4.2 years, range: 2-18 years), occurring a mean of 18.3 ± 10.3 days following ESBS. All abnormal findings were noted in patients age ≤12 years. Synechiae were noted in 8.7% of cases, bacterial rhinosinusitis in 2.9%, and failed reconstruction with cerebrospinal fluid leak in 4.5% (two cases of flap malposition and one case of flap necrosis). All failed reconstructions were noted following expanded endonasal cases for craniopharyngioma, and in each case, a revision reconstruction was performed during the second-look surgery. Synechiae were not significantly associated with younger age, revision cases, or cases with reconstructive flaps. There were no perioperative complications. Conclusion Second-look debridement under general anesthesia may be useful in the identification and intervention of sinonasal pathology following endoscopic skull base surgery, particularly in children ≤12 years old or those with pedicled flap reconstructions. Larger controlled studies are warranted to validate this practice and refine indications and timing of this second procedure.

Endoscopic Transnasal Management of Meningoceles and Encephaloceles in Children: A Systematic Review.

OBJECTIVE: To review surgical techniques used in the endoscopic transnasal repair of pediatric basal meningoencephaloceles and compare perioperative outcomes in children <2 and ≥2 years old. DATA SOURCES: MEDLINE, EMBASE, and CENTRAL. REVIEW METHODS: Data sources were searched from inception to August 22, 2022, using search terms relevant to endoscopic transnasal meningoencephalocele repair in children. Reviews and Meta-analyses were excluded. Primary outcomes were the incidence of intraoperative and postoperative complications, including cerebrospinal fluid leak, recurrence, and reintervention. Quality assessments were performed using Newcastle-Ottawa Scale, ROBIN-I, and NIH. RESULTS: Overall, 217 patients across 61 studies were identified. The median age at surgery was 4 years (0-18 years). Fifty percent were female; 31% were <2 years. Most defects were meningoencephaloceles (56%), located transethmoidal (80%), and of congenital origin (83%). Seventy-five percent of repairs were multilayered. Children ≥2 years underwent multilayer repairs more frequently than those <2 years (P = 0.004). Children <2 years more frequently experienced postoperative cerebrospinal fluid leaks (P = 0.02), meningoencephalocele recurrence (P < 0.0001), and surgical reintervention (P = 0.005). Following multilayer repair, children <2 years were more likely to experience recurrence (P = 0.0001) and reintervention (P = 0.006). CONCLUSION: Younger children with basal meningoencephaloceles appear to be at greater risk of postoperative complications following endoscopic endonasal repair, although the quality of available evidence is weakened by incomplete reporting. In the absence of preoperative cerebrospinal fluid leak or meningitis, it may be preferable to delay surgery as access is more conducive to successful repair in older children.

Sinus pericranii in the setting of a posterior fossa pilocytic astrocytoma: illustrative case.

BACKGROUND: Sinus pericranii (SP) is a rare vascular anomaly, with an uncertain etiology. Often discovered as superficial lesions, they can be primary or secondary in nature. Herein, we report a rare case of SP in the setting of a large posterior fossa pilocytic astrocytoma associated with a significant venous network. OBSERVATIONS: A 12-year-old male presented with acute clinical deterioration in extremis with a 2-month history of lethargy and headaches. Outside plain computed tomography imaging revealed a large posterior fossa cystic lesion, probably a tumor, with severe hydrocephalus. There was also a midline small skull defect at the opisthocranion, without visible vascular anomalies. An external ventricular drain was placed with rapid recovery. Contrast imaging revealed a large midline SP emanating from occipital bone with a large intraosseous, and subcutaneous venous plexus in the midline draining inferiorly into venous plexus around the craniocervical junction. A posterior fossa craniotomy without contrast imaging could have resulted in catastrophic hemorrhage. A small modified off-center craniotomy provided access to the tumor with a gross total excision. LESSONS: SP is a rare but significant phenomenon. Its presence does not necessarily preclude resection of underlying tumors, provided that a careful preoperative assessment of the venous anomaly is undertaken.

Intracranial Artery Morphology in Pediatric Moya Moya Disease and Moya Moya Syndrome.

BACKGROUND: Moya Moya disease (MMD) and Moya Moya syndrome (MMS) are cerebrovascular disorders, which affect the internal carotid arteries (ICAs). Diagnosis and surveillance of MMD/MMS in children mostly rely on qualitative evaluation of vascular imaging, especially MR angiography (MRA). OBJECTIVE: To quantitatively characterize arterial differences in pediatric patients with MMD/MMS compared with normal controls. METHODS: MRA data sets from 17 presurgery MMD/MMS (10M/7F, mean age = 10.0 years) patients were retrospectively collected and compared with MRA data sets of 98 children with normal vessel morphology (49 male patients; mean age = 10.6 years). Using a level set segmentation method with anisotropic energy weights, the cerebral arteries were automatically extracted and used to compute the radius of the ICA, middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA), and basilar artery (BA). Moreover, the density and the average radius of all arteries in the MCA, ACA, and PCA flow territories were quantified. RESULTS: Statistical analysis revealed significant differences comparing children with MMD/MMS and those with normal vasculature ( P < .001), whereas post hoc analyses identified significantly smaller radii of the ICA, MCA-M1, MCA-M2, and ACA ( P < .001) in the MMD/MMS group. No significant differences were found for the radii of the PCA and BA or any artery density and average artery radius measurement in the flow territories ( P > .05). CONCLUSION: His study describes the results of an automatic approach for quantitative characterization of the cerebrovascular system in patients with MMD/MMS with promising preliminary results for quantitative surveillance in pediatric MMD/MMS management.

Acetazolamide-Challenged Arterial Spin Labeling Detects Augmented Cerebrovascular Reserve After Surgery for Moyamoya.

BACKGROUND: Cerebrovascular reserve (CVR) inversely correlates with stroke risk in children with Moyamoya disease and may be improved by revascularization surgery. We hypothesized that acetazolamide-challenged arterial spin labeling MR perfusion quantifies augmentation of CVR achieved by revascularization and correlates with currently accepted angiographic scoring criteria. METHODS: We retrospectively identified pediatric patients with Moyamoya disease or syndrome who received cerebral revascularization at ≤18 years of age between 2012 and 2019 at our institution. Using acetazolamide-challenged arterial spin labeling, we compared postoperative CVR to corresponding preoperative values and to postoperative perfusion outcomes classified by Matsushima grading. RESULTS: In this cohort, 32 patients (17 males) with Moyamoya underwent 29 direct and 16 indirect extracranial-intracranial bypasses at a median 9.7 years of age (interquartile range, 7.6-15.7). Following revascularization, median CVR increased within the ipsilateral middle cerebral artery territory (6.9 mL/100 g per minute preoperatively versus 16.5 mL/100 g per minute postoperatively, P<0.01). No differences were observed in the ipsilateral anterior cerebral artery (P=0.13) and posterior cerebral artery (P=0.48) territories. Postoperative CVR was higher in the ipsilateral middle cerebral artery territories of patients who achieved Matsushima grade A perfusion, in comparison to those with grades B or C (25.8 versus 17.5 mL, P=0.02). The method of bypass (direct or indirect) did not alter relative increases in CVR (8 versus 3.8 mL/100 g per minute, P=0.7). CONCLUSIONS: Acetazolamide-challenged arterial spin labeling noninvasively quantifies augmentation of CVR following surgery for Moyamoya disease and syndrome.

Age-dependent Intracranial Artery Morphology in Healthy Children.

PURPOSE: Evaluation of intracranial artery morphology plays an important role in diagnosing a variety of neurovascular diseases. In addition to clinical symptoms, diagnosis currently relies on qualitative rather than quantitative evaluation of vascular imaging sequences, such as magnetic resonance angiography (MRA). However, there is a paucity of literature on normal arterial morphology in the pediatric population across brain development. We aimed to quantitatively assess normal, age-related changes in artery morphology in children. METHODS: We performed retrospective analysis of pediatric MRA data obtained from a tertiary referral center. An MRA dataset from 98 children (49 boys/49 girls) aged 0.6-20 years (median = 11.5 years) with normal intracranial vasculature was retrospectively collected between 2011 and 2018. All arteries were automatically segmented to determine the vessel radius. Using an atlas-based approach, the average radius and density of arteries were measured in the three main cerebral vascular territories and the radius of five major arteries was determined at corresponding locations. RESULTS: The radii of the major arteries as well as the average artery radius and density in the different vascular territories in the brain remained constant throughout childhood and adolescence (|r| < 0.369 in all cases). CONCLUSION: This study presents the first automated evaluation of intracranial vessel morphology on MRA across childhood. Our results can serve as a framework for quantitative evaluation of cerebral vessel morphology in the setting of pediatric neurovascular diseases.

Incorporating patient-centered quality-of-life measures for outcome assessment after Chiari malformation type I decompression in a pediatric population: a pilot study.

OBJECTIVE: Optimal management of pediatric Chiari malformation type I (CM-I) is much debated, chiefly due to the lack of validated tools for outcome assessment, with very few tools incorporating patient-centered measures of health-related quality of life (HRQOL). Although posterior fossa decompression (PFD) benefits a subset of patients, prediction of its impact across patients is challenging. The primary aim of this study was to investigate the role of patient-centered HRQOL measures in the assessment and prediction of outcomes after PFD. METHODS: The authors collected HRQOL data from a cohort of 20 pediatric CM-I patients before and after PFD. The surveys included assessments of selected Patient-Reported Outcomes Measurement Information System (PROMIS) health domains and were used to generate the PROMIS preference (PROPr) score, which is a measure of HRQOL. PROMIS is a reliable standardized measure of HRQOL domains such as pain, fatigue, depression, and physical function, which are all relevant to CM-I. The authors then compared the PROPr scores with Chicago Chiari Outcome Scale (CCOS) scores derived from time-matched clinical documentation. Finally, the authors used the PROPr scores as an outcome measure to predict postsurgical HRQOL improvement at 1 year on the basis of patient demographic characteristics, comorbidities, and radiological and physical findings. The Wilcoxon signed-rank test, Mann-Whitney U-test, and Kendall's correlation were used for statistical analysis. RESULTS: Aggregate analysis revealed improvement of pain severity after PFD (p = 0.007) in anatomical patterns characteristic of CM-I. Most PROMIS domain scores trended toward improvement after surgery, with anxiety and pain interference reaching statistical significance (p < 0.002 and p < 0.03, respectively). PROPr scores also significantly improved after PFD (p < 0.008). Of the baseline patient characteristics, preexisting scoliosis was the most accurate negative predictor of HRQOL improvement after PFD (median -0.095 vs 0.106, p < 0.001). A correlation with modest magnitude (Kendall's tau range 0.19-0.47) was detected between the patient-centered measures and CCOS score. CONCLUSIONS: The authors observed moderate improvement of HRQOL, when measured using a modified panel of PROMIS question banks, in this pilot cohort of pediatric CM-I patients after PFD. Further investigations are necessary to validate this tool for children with CM-I and to determine whether these scores correlate with clinical and radiographic findings.

Early Effects of COVID-19 Pandemic on Neurosurgical Training in the United States: A Case Volume Analysis of 8 Programs.

OBJECTIVE: To determine the impact of the 2019 novel coronavirus disease (COVID-19) pandemic on operative case volume in 8 U.S. neurosurgical residency training programs in early 2020 and to survey these programs regarding training activities during this period. METHODS: A retrospective review was conducted of monthly operative case volumes and types for 8 residency programs for 2019 and January through April 2020. Cases were grouped as elective cranial, elective spine, and nonelective emergent cases. Programs were surveyed regarding residents' perceptions of the impact of COVID-19 on surgical training, didactics, and research participation. Data were analyzed for individual programs and pooled across programs. RESULTS: Across programs, the 2019 monthly mean ± SD case volume was 211 ± 82; 2020 mean ± SD case volumes for January, February, March, and April were 228 ± 93, 214 ± 84, 180 ± 73, and 107 ± 45. Compared with 2019, March and April 2020 mean cases declined 15% (P = 0.003) and 49% (P = 0.002), respectively. COVID-19 affected surgical case volume for all programs; 75% reported didactics negatively affected, and 90% reported COVID-19 resulted in increased research time. Several neurosurgery residents required COVID-19 testing; however, to our knowledge, only 1 resident from the participating programs tested positive. CONCLUSIONS: This study documents a significant reduction in operative volume in 8 neurosurgery residency training programs in early 2020. During this time, neurosurgery residents engaged in online didactics and research-related activities, reporting increased research productivity. Residency programs should collect data to determine the educational impact of the COVID-19 pandemic on residents' operative case volumes, identify deficiencies, and develop plans to mitigate any effects.

Artificial intelligence for automatic cerebral ventricle segmentation and volume calculation: a clinical tool for the evaluation of pediatric hydrocephalus.

OBJECTIVE: Imaging evaluation of the cerebral ventricles is important for clinical decision-making in pediatric hydrocephalus. Although quantitative measurements of ventricular size, over time, can facilitate objective comparison, automated tools for calculating ventricular volume are not structured for clinical use. The authors aimed to develop a fully automated deep learning (DL) model for pediatric cerebral ventricle segmentation and volume calculation for widespread clinical implementation across multiple hospitals. METHODS: The study cohort consisted of 200 children with obstructive hydrocephalus from four pediatric hospitals, along with 199 controls. Manual ventricle segmentation and volume calculation values served as "ground truth" data. An encoder-decoder convolutional neural network architecture, in which T2-weighted MR images were used as input, automatically delineated the ventricles and output volumetric measurements. On a held-out test set, segmentation accuracy was assessed using the Dice similarity coefficient (0 to 1) and volume calculation was assessed using linear regression. Model generalizability was evaluated on an external MRI data set from a fifth hospital. The DL model performance was compared against FreeSurfer research segmentation software. RESULTS: Model segmentation performed with an overall Dice score of 0.901 (0.946 in hydrocephalus, 0.856 in controls). The model generalized to external MR images from a fifth pediatric hospital with a Dice score of 0.926. The model was more accurate than FreeSurfer, with faster operating times (1.48 seconds per scan). CONCLUSIONS: The authors present a DL model for automatic ventricle segmentation and volume calculation that is more accurate and rapid than currently available methods. With near-immediate volumetric output and reliable performance across institutional scanner types, this model can be adapted to the real-time clinical evaluation of hydrocephalus and improve clinician workflow.

Deep Learning for Automated Delineation of Pediatric Cerebral Arteries on Pre-operative Brain Magnetic Resonance Imaging.

Introduction: Surgical resection of brain tumors is often limited by adjacent critical structures such as blood vessels. Current intraoperative navigations systems are limited; most are based on two-dimensional (2D) guidance systems that require manual segmentation of any regions of interest (ROI; eloquent structures to avoid or tumor to resect). They additionally require time- and labor-intensive processing for any reconstruction steps. We aimed to develop a deep learning model for real-time fully automated segmentation of the intracranial vessels on preoperative non-angiogram imaging sequences. Methods: We identified 48 pediatric patients (10-months to 22-years old) with high resolution (0.5-1 mm axial thickness) isovolumetric, pre-operative T2 magnetic resonance images (MRIs). Twenty-eight patients had anatomically normal brains, and 20 patients had tumors or other lesions near the skull base. Manually segmented intracranial vessels (internal carotid, middle cerebral, anterior cerebral, posterior cerebral, and basilar arteries) served as ground truth labels. Patients were divided into 80/5/15% training/validation/testing sets. A modified 2-D Unet convolutional neural network (CNN) architecture implemented with 5 layers was trained to maximize the Dice coefficient, a measure of the correct overlap between the predicted vessels and ground truth labels. Results: The model was able to delineate the intracranial vessels in a held-out test set of normal and tumor MRIs with an overall Dice coefficient of 0.75. While manual segmentation took 1-2 h per patient, model prediction took, on average, 8.3 s per patient. Conclusions: We present a deep learning model that can rapidly and automatically identify the intracranial vessels on pre-operative MRIs in patients with normal vascular anatomy and in patients with intracranial lesions. The methodology developed can be translated to other critical brain structures. This study will serve as a foundation for automated high-resolution ROI segmentation for three-dimensional (3D) modeling and integration into an augmented reality navigation platform.

Mortality prediction and long-term outcomes for civilian cerebral gunshot wounds: A decision-tree algorithm based on a single trauma center.

Gunshot wounds (GSW) are one of the most lethal forms of head trauma. The lack of clear guidelines for civilian GSW complicates surgical management. We aimed to develop a decision-tree algorithm for mortality prediction and report long-term outcomes on survivors based on 15-year data from our level 1 trauma center. We retrospectively reviewed 96 consecutive patients who presented with cerebral GSWs between 2003 and 2018. Clinical information from our trauma database, EMR, and relevant imaging scans was reviewed. A decision-tree model was constructed based on variables showing significant differences between survivors and non-survivors. After excluding patients who died at arrival, 54 patients with radiologically confirmed intracranial injury were included. Compared to survivors (51.9%), non-survivors (48.1%) were significantly more likely to have perforating (entry and exit wound), as opposed to penetrating (entry wound only), injuries. Bi-hemispheric and posterior fossa involvement, cerebral herniation, and intraventricular hemorrhage were more commonly present in non-survivors. Based on the decision-tree, Glasgow Coma Scale (GCS) > 8 and penetrating, uni-hemispheric injury predicted survival. Among patients with GCS ≤ 8 and normal pupillary response, lack of 1) posterior fossa involvement, 2) cerebral herniation, 3) bi-hemispheric injury, and 4) intraventricular hemorrhage, were associated with survival. Favorable long-term outcomes (mean follow-up 34.4 months) were possible for survivors who required neurosurgery and stable patients who were conservatively managed. We applied clinical and radiological characteristics that predicted survival to construct a decision-tree to facilitate surgical decision-making for GSW. Further validation of the algorithm in a large patient setting is recommended.

Early Diffusion Magnetic Resonance Imaging Changes in Normal-Appearing Brain in Pediatric Moyamoya Disease.

BACKGROUND: Moyamoya disease often leads to ischemic strokes visible on diffusion-weighted imaging (DWI) and T2-weighted magnetic resonance imaging (MRI) with subsequent cognitive impairment. In adults with moyamoya, apparent diffusion coefficient (ADC) is correlated with regions of steal phenomenon and executive dysfunction prior to white matter changes. OBJECTIVE: To investigate quantitative global diffusion changes in pediatric moyamoya patients prior to explicit structural ischemic damage. METHODS: We retrospectively reviewed children (<20 yr old) with moyamoya disease and syndrome who underwent bypass surgery at our institution. We identified 29 children with normal structural preoperative MRI and without findings of cortical infarction or chronic white matter ischemic changes. DWI datasets were used to calculate ADC maps for each subject as well as for 60 age-matched healthy controls. Using an atlas-based approach, the cerebral white matter, cerebral cortex, thalamus, caudate, putamen, pallidum, hippocampus, amygdala, nucleus accumbens, and brainstem were segmented in each DWI dataset and used to calculate regional volumes and ADC values. RESULTS: Multivariate analysis of covariance using the regional ADC and volume values as dependent variables and age and gender as covariates revealed a significant difference between the groups (P < .001). Post hoc analysis demonstrated significantly elevated ADC values for children with moyamoya in the cerebral cortex, white matter, caudate, putamen, and nucleus accumbens. No significant volume differences were found. CONCLUSION: Prior to having bypass surgery, and in the absence of imaging evidence of ischemic stroke, children with moyamoya exhibit cerebral diffusion changes. These findings could reflect microstructural changes stemming from exhaustion of cerebrovascular reserve.

Diffusion tensor magnetic resonance imaging of the optic nerves in pediatric hydrocephalus.

OBJECTIVE: While conventional imaging can readily identify ventricular enlargement in hydrocephalus, structural changes that underlie microscopic tissue injury might be more difficult to capture. MRI-based diffusion tensor imaging (DTI) uses properties of water motion to uncover changes in the tissue microenvironment. The authors hypothesized that DTI can identify alterations in optic nerve microstructure in children with hydrocephalus. METHODS: The authors retrospectively reviewed 21 children (< 18 years old) who underwent DTI before and after neurosurgical intervention for acute obstructive hydrocephalus from posterior fossa tumors. Their optic nerve quantitative DTI metrics of mean diffusivity (MD) and fractional anisotropy (FA) were compared to those of 21 age-matched healthy controls. RESULTS: Patients with hydrocephalus had increased MD and decreased FA in bilateral optic nerves, compared to controls (p < 0.001). Normalization of bilateral optic nerve MD and FA on short-term follow-up (median 1 day) after neurosurgical intervention was observed, as was near-complete recovery of MD on long-term follow-up (median 1.8 years). CONCLUSIONS: DTI was used to demonstrate reversible alterations of optic nerve microstructure in children presenting acutely with obstructive hydrocephalus. Alterations in optic nerve MD and FA returned to near-normal levels on short- and long-term follow-up, suggesting that surgical intervention can restore optic nerve tissue microstructure. This technique is a safe, noninvasive imaging tool that quantifies alterations of neural tissue, with a potential role for evaluation of pediatric hydrocephalus.