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1.
Neurosurg Rev ; 47(1): 294, 2024 Jun 26.
Article in English | MEDLINE | ID: mdl-38922363

ABSTRACT

Meningiomas are the most common intracranial tumors, predominantly affecting adults, with a higher incidence in female and elderly populations. Despite their prevalence, research on neurocognitive impairment in meningioma patients remains limited compared to intra-axial tumors such as gliomas. We conducted a comprehensive systematic review of the current literature on neurocognitive outcomes in meningioma patients pre- and post-surgery. Our review revealed significant disparities in reported neurocognitive outcomes, with prospective studies suggesting tumor-related factors as the primary contributors to postoperative deficits, while retrospective studies imply surgical intervention plays a significant role. Regardless of study design or specifics, most studies lack baseline preoperative neurocognitive assessments and standardized protocols for evaluating neurocognitive function. To address these gaps, we advocate for standardized neurocognitive assessment protocols, consensus on neurocognitive domains to be targeted in this population by tailored test batteries, and more prospective studies to elucidate correlations between tumor characteristics, patient attributes, surgical interventions, neurocognitive status, and planning for implementing tailored neurocognitive rehabilitation strategies early in the postoperative course which is crucial for achieving optimal long-term neurocognitive outcomes and enhancing patients' quality of life.


Subject(s)
Meningeal Neoplasms , Meningioma , Humans , Meningioma/surgery , Meningioma/complications , Meningeal Neoplasms/surgery , Meningeal Neoplasms/complications , Meningeal Neoplasms/psychology , Quality of Life , Cognitive Dysfunction/etiology , Neuropsychological Tests , Neurocognitive Disorders/etiology , Neurosurgical Procedures/methods
2.
Article in English | MEDLINE | ID: mdl-38683716

ABSTRACT

Mixed-precision Deep Neural Networks (DNNs) provide an efficient solution for hardware deployment, especially under resource constraints, while maintaining model accuracy. Identifying the ideal bit precision for each layer, however, remains a challenge given the vast array of models, datasets, and quantization schemes, leading to an expansive search space. Recent literature has addressed this challenge, resulting in several promising frameworks. This paper offers a comprehensive overview of the standard quantization classifications prevalent in existing studies. A detailed survey of current mixed-precision frameworks is provided, with an in-depth comparative analysis highlighting their respective merits and limitations. The paper concludes with insights into potential avenues for future research in this domain.

3.
Childs Nerv Syst ; 40(3): 759-768, 2024 Mar.
Article in English | MEDLINE | ID: mdl-37966499

ABSTRACT

Distraction osteogenesis is utilized to increase intracranial volume in the treatment of restrictive pathologies, most commonly syndromic synostosis. Children too young for open calvarial vault expansion or other systemic or local contraindications to a direct reconstructive approach benefit greatly from distraction osteogenesis, typically addressing posterior vault expansion. Wound infection, cerebrospinal fluid (CSF) leak, device failure, need for a second surgery for removal, and cost, are issues that can limit the use of this approach. These challenges are more pronounced in low- and middle-income countries (LMICs) due to lack of access to the device, the financial burden of the need for a second surgery, and the severity of the implications of infection and CSF leak. Over the last five decades, there has been an increased acceptance of bioresorbable instrumentation in craniofacial surgery. Poly L-lactic acid, polyglycolic acid, and polydioxanone are the most commonly used polymers. New resorbable fixation tools such as ultrasound-activated pins and heat-activated pins are superior to conventional bioresorbable screws in allowing attachment to thinner bone plates. In this paper, we present a review of the literature on cranial vault distraction and the use of bioresorbable materials and propose a novel design of a fully absorbable cranial distractor system using external magnetic distraction control, eliminating the need for external activation ports and a second surgery to remove the hardware. The application of this technology in LMIC settings could advance access to care and treatment options for patients with syndromic synostosis.


Subject(s)
Craniosynostoses , Osteogenesis, Distraction , Child , Humans , Infant , Skull/surgery , Craniosynostoses/surgery , Bone Nails , Image Processing, Computer-Assisted , Cerebrospinal Fluid Leak
5.
Neurosurg Rev ; 46(1): 146, 2023 Jun 24.
Article in English | MEDLINE | ID: mdl-37354243

ABSTRACT

Cranial irradiation is associated with several adverse events such as endocrinopathy, growth retardation, neurocognitive impairment, secondary malignancies, cerebral vasculopathy, and potential stroke. The better side effects profile of proton beam therapy compared with that of photon radiation therapy is due to its physical properties, mainly the sharp dose fall-off after energy deposition in the Bragg peak. Despite the better toxicity profile of proton beam therapy, the risk of  moyamoya syndrome still exists. We conducted a systematic review of the existing literature on moyamoya syndrome after receiving cranial radiation therapy for pediatric brain tumors to investigate the incidence of moyamoya syndrome after receiving photon versus proton radiation therapy. In this review, we report that the incidence of moyamoya syndrome after receiving proton beam therapy is almost double that of photon-induced moyamoya syndrome. Patients who received proton beam therapy for the management of pediatric brain tumors are more likely to develop moyamoya syndrome at the age of less than 5 years. Meanwhile, most patients with proton-induced moyamoya are more likely to be diagnosed within the first 2 years after the completion of their proton beam therapy.


Subject(s)
Brain Neoplasms , Moyamoya Disease , Proton Therapy , Child , Humans , Child, Preschool , Proton Therapy/adverse effects , Moyamoya Disease/epidemiology , Moyamoya Disease/etiology , Protons , Incidence , Brain Neoplasms/complications
6.
Front Neurosci ; 17: 1047008, 2023.
Article in English | MEDLINE | ID: mdl-37090791

ABSTRACT

Directly training spiking neural networks (SNNs) has remained challenging due to complex neural dynamics and intrinsic non-differentiability in firing functions. The well-known backpropagation through time (BPTT) algorithm proposed to train SNNs suffers from large memory footprint and prohibits backward and update unlocking, making it impossible to exploit the potential of locally-supervised training methods. This work proposes an efficient and direct training algorithm for SNNs that integrates a locally-supervised training method with a temporally-truncated BPTT algorithm. The proposed algorithm explores both temporal and spatial locality in BPTT and contributes to significant reduction in computational cost including GPU memory utilization, main memory access and arithmetic operations. We thoroughly explore the design space concerning temporal truncation length and local training block size and benchmark their impact on classification accuracy of different networks running different types of tasks. The results reveal that temporal truncation has a negative effect on the accuracy of classifying frame-based datasets, but leads to improvement in accuracy on event-based datasets. In spite of resulting information loss, local training is capable of alleviating overfitting. The combined effect of temporal truncation and local training can lead to the slowdown of accuracy drop and even improvement in accuracy. In addition, training deep SNNs' models such as AlexNet classifying CIFAR10-DVS dataset leads to 7.26% increase in accuracy, 89.94% reduction in GPU memory, 10.79% reduction in memory access, and 99.64% reduction in MAC operations compared to the standard end-to-end BPTT. Thus, the proposed method has shown high potential to enable fast and energy-efficient on-chip training for real-time learning at the edge.

7.
Sci Rep ; 13(1): 3912, 2023 Mar 08.
Article in English | MEDLINE | ID: mdl-36890156

ABSTRACT

Quantum computers have enabled solving problems beyond the current machines' capabilities. However, this requires handling noise arising from unwanted interactions in these systems. Several protocols have been proposed to address efficient and accurate quantum noise profiling and mitigation. In this work, we propose a novel protocol that efficiently estimates the average output of a noisy quantum device to be used for quantum noise mitigation. The multi-qubit system average behavior is approximated as a special form of a Pauli Channel where Clifford gates are used to estimate the average output for circuits of different depths. The characterized Pauli channel error rates, and state preparation and measurement errors are then used to construct the outputs for different depths thereby eliminating the need for large simulations and enabling efficient mitigation. We demonstrate the efficiency of the proposed protocol on four IBM Q 5-qubit quantum devices. Our method demonstrates improved accuracy with efficient noise characterization. We report up to 88% and 69% improvement for the proposed approach compared to the unmitigated, and pure measurement error mitigation approaches, respectively.

8.
Exp Neurol ; 354: 114104, 2022 08.
Article in English | MEDLINE | ID: mdl-35525306

ABSTRACT

The use of touchscreen technology to evaluate cognitive deficits in animal models has grown tremendously over the past 20 years. The touchscreen apparatus encompasses many advantages, namely a high level of standardization and translational capability. Improvements in technology in recent years have expanded the versatility of the touchscreen platform, as it is able to test distinct cognitive modalities including working memory, attention, discrimination, and association. Importantly, touchscreen technology has allowed researchers to explore deficits in multiple pillars of cognition in a wide variety of perinatal disorders with neurological sequelae across critical developmental windows. The touchscreen platform has been used to dissect deficits in antenatal CNS injury including fetal alcohol syndrome, prenatal opioid exposure, and chorioamnionitis, to peripartum insults such as term hypoxic-ischemic encephalopathy, to early postnatal insults including infantile traumatic brain injury. Most importantly, touchscreen technology offers the sensitivity necessary to detect subtle injury and treatment-induced changes in cognition and executive function beyond those offered by more rudimentary tests of rodent cognition. Understanding the pathophysiology of these disorders in rodents is paramount to addressing these deficits in human infants and dissecting the neural circuitry essential to perinatal brain injury pathophysiology and responsiveness to novel therapeutics. Touchscreen testing provides an effective, facile, sophisticated technique to accelerate the goal of improving cognitive and behavioral outcomes of children who suffer perinatal brain injury.


Subject(s)
Brain Injuries , Executive Function , Animals , Brain Injuries/etiology , Cognition , Executive Function/physiology , Female , Humans , Memory, Short-Term , Pregnancy , Technology
9.
Dev Neurosci ; 44(4-5): 266-276, 2022.
Article in English | MEDLINE | ID: mdl-35358965

ABSTRACT

Cerebral palsy (CP) is the most common cause of physical disability for children worldwide. Many infants and toddlers are not diagnosed with CP until they fail to achieve obvious motor milestones. Currently, there are no effective pharmacologic interventions available for infants and toddlers to substantially improve their trajectory of neurodevelopment. Because children with CP from preterm birth also exhibit a sustained immune system hyper-reactivity, we hypothesized that neuro-immunomodulation with a regimen of repurposed endogenous neurorestorative medications, erythropoietin (EPO) and melatonin (MLT), could improve this trajectory. Thus, we administered EPO + MLT to rats with CP during human infant-toddler equivalency to determine whether we could influence gait patterns in mature animals. After a prenatal injury on embryonic day 18 (E18) that mimics chorioamnionitis at ∼25 weeks human gestation, rat pups were born and raised with their dam. Beginning on postnatal day 15 (P15), equivalent to human infant ∼1 year, rats were randomized to receive either a regimen of EPO + MLT or vehicle (sterile saline) through P20. Gait was assessed in young adult rats at P30 using computerized digital gait analyses including videography on a treadmill. Results indicate that gait metrics of young adult rats treated with an infantile cocktail of EPO + MLT were restored compared to vehicle-treated rats (p < 0.05) and similar to sham controls. These results provide reassuring evidence that pharmacological interventions may be beneficial to infants and toddlers who are diagnosed with CP well after the traditional neonatal window of intervention.


Subject(s)
Brain Injuries , Erythropoietin , Melatonin , Premature Birth , Animals , Brain Injuries/drug therapy , Erythropoietin/pharmacology , Female , Gait , Humans , Infant , Melatonin/pharmacology , Pregnancy , Rats
10.
Front Neuroinform ; 16: 771730, 2022.
Article in English | MEDLINE | ID: mdl-35250525

ABSTRACT

The automatic fitting of spiking neuron models to experimental data is a challenging problem. The integrate and fire model and Hodgkin-Huxley (HH) models represent the two complexity extremes of spiking neural models. Between these two extremes lies two and three differential-equation-based models. In this work, we investigate the problem of parameter estimation of two simple neuron models with a sharp reset in order to fit the spike timing of electro-physiological recordings based on two problem formulations. Five optimization algorithms are investigated; three of them have not been used to tackle this problem before. The new algorithms show improved fitting when compared with the old ones in both problems under investigation. The improvement in fitness function is between 5 and 8%, which is achieved by using the new algorithms while also being more consistent between independent trials. Furthermore, a new problem formulation is investigated that uses a lower number of search space variables when compared to the ones reported in related literature.

11.
Light Sci Appl ; 11(1): 3, 2022 Jan 01.
Article in English | MEDLINE | ID: mdl-34974516

ABSTRACT

Neuromorphic vision sensors have been extremely beneficial in developing energy-efficient intelligent systems for robotics and privacy-preserving security applications. There is a dire need for devices to mimic the retina's photoreceptors that encode the light illumination into a sequence of spikes to develop such sensors. Herein, we develop a hybrid perovskite-based flexible photoreceptor whose capacitance changes proportionally to the light intensity mimicking the retina's rod cells, paving the way for developing an efficient artificial retina network. The proposed device constitutes a hybrid nanocomposite of perovskites (methyl-ammonium lead bromide) and the ferroelectric terpolymer (polyvinylidene fluoride trifluoroethylene-chlorofluoroethylene). A metal-insulator-metal type capacitor with the prepared composite exhibits the unique and photosensitive capacitive behavior at various light intensities in the visible light spectrum. The proposed photoreceptor mimics the spectral sensitivity curve of human photopic vision. The hybrid nanocomposite is stable in ambient air for 129 weeks, with no observable degradation of the composite due to the encapsulation of hybrid perovskites in the hydrophobic polymer. The functionality of the proposed photoreceptor to recognize handwritten digits (MNIST) dataset using an unsupervised trained spiking neural network with 72.05% recognition accuracy is demonstrated. This demonstration proves the potential of the proposed sensor for neuromorphic vision applications.

12.
IEEE Trans Neural Netw Learn Syst ; 33(8): 3988-4002, 2022 08.
Article in English | MEDLINE | ID: mdl-33571097

ABSTRACT

The performance of a biologically plausible spiking neural network (SNN) largely depends on the model parameters and neural dynamics. This article proposes a parameter optimization scheme for improving the performance of a biologically plausible SNN and a parallel on-field-programmable gate array (FPGA) online learning neuromorphic platform for the digital implementation based on two numerical methods, namely, the Euler and third-order Runge-Kutta (RK3) methods. The optimization scheme explores the impact of biological time constants on information transmission in the SNN and improves the convergence rate of the SNN on digit recognition with a suitable choice of the time constants. The parallel digital implementation leads to a significant speedup over software simulation on a general-purpose CPU. The parallel implementation with the Euler method enables around 180× ( 20× ) training (inference) speedup over a Pytorch-based SNN simulation on CPU. Moreover, compared with previous work, our parallel implementation shows more than 300× ( 240× ) improvement on speed and 180× ( 250× ) reduction in energy consumption for training (inference). In addition, due to the high-order accuracy, the RK3 method is demonstrated to gain 2× training speedup over the Euler method, which makes it suitable for online training in real-time applications.


Subject(s)
Neural Networks, Computer , Neurons , Action Potentials , Computer Simulation , Learning
13.
World Neurosurg ; 159: 48-53, 2022 03.
Article in English | MEDLINE | ID: mdl-34954057

ABSTRACT

Rhombencephalosynapsis is a rare congenital anomaly, characterized by partial or total agenesis of the cerebellar vermis with midline fusion of the cerebellar hemispheres, dentate nuclei, and the superior cerebellar peduncles, creating the distinctive keyhole appearance of the fourth ventricle. Rhombencephalosynapsis can be isolated or can occur in association with other congenital anomalies and syndromes such as Gómez-López-Hernández syndrome (GLHS) or VACTERL: vertebral anomalies (V), anal atresia (A), cardiovascular defects (C), esophageal atresia and/or tracheoesophageal fistula (TE), and renal (R) and limb/radial (L) anomalies. Recent advances in prenatal imaging have resulted in an increasing rate of prenatal diagnosis of abnormalities of the posterior fossa including rhombencephalosynapsis. Patients with rhombencephalosynapsis may present with motor developmental delay, ataxia, swallowing difficulties, muscular hypotonia, spastic quadriparesis, abnormal eye movements, and a characteristic "figure-of-eight" head shaking. Cognitive outcome varies from severe intellectual disability to normal intellectual function. Rhombencephalosynapsis with VACTERL is often associated with severe cognitive disabilities, whereas patients with GLHS may have better cognitive function. The most common associated findings with rhombencephalosynapsis include hydrocephalus, mesencephalosynapsis, holoprosencephaly, pontocerebellar hypoplasia, corpus callosum dysgenesis, and absence of septum pellucidum. Patients can be categorized into 4 groups: 1) rhombencephalosynapsis associated with GLHS; 2) rhombencephalosynapsis with VACTERL; 3) rhombencephalosynapsis with atypical holoprosencephaly, and 4) isolated rhomboencephalosynapsis. The etiology of rhombencephalosynapsis is unknown. Here, we discuss several hypotheses about its etiology.


Subject(s)
Abnormalities, Multiple , Craniofacial Abnormalities , Holoprosencephaly , Neurocutaneous Syndromes , Abnormalities, Multiple/diagnosis , Alopecia , Cerebellum/abnormalities , Craniofacial Abnormalities/diagnosis , Female , Growth Disorders , Humans , Pregnancy , Rhombencephalon
14.
J Adv Res ; 32: 119-131, 2021 Sep.
Article in English | MEDLINE | ID: mdl-34484831

ABSTRACT

INTRODUCTION: Optimal charging of RC circuits is a well-studied problem in the integer-order domain due to its importance from economic and system temperature hazards perspectives. However, the fractional-order counterpart of this problem requires investigation. OBJECTIVES: This study aims to find approximate solutions of the most energy-efficient input charging function in fractional-order RC circuits. METHODS: This paper uses a meta-heuristic optimization technique called Cuckoo search optimizer to attain the maximum charging efficiency of three common fractional-order RC circuits. An analytical expression of the fractional capacitor voltage is suggested such that it satisfies the boundary conditions of the optimal charging problem. The problem is formulated as a fractional-order calculus of variations problem with compositional functional. The numerical solutions are obtained with the meta-heuristic optimization algorithm's help to avoid the complexities of the analytical approach. RESULTS: he efficiency surfaces and input voltage charging curves are discussed for fractional-order in the range 0.5 < α ≤ 1 . CONCLUSION: The optimized charging function can approximate the optimal charging curve using at most 4 terms. The charging time and the resistive parameters have the most dominant effect on charging efficiency at constant fractional-order α .

15.
Surg Neurol Int ; 12: 416, 2021.
Article in English | MEDLINE | ID: mdl-34513180

ABSTRACT

BACKGROUND: The advancement of endoscopic techniques in the past decade has improved the surgical management of cerebellopontine angle (CPA) tumors. Endoscope-assisted microsurgery improves the ability to evaluate the extent of resection, achieve safe tumor resection and reduce the risk of surgery-related morbidity. METHODS: In this study, we used a cadaveric model to demonstrate a step by step endoscope-assisted microsurgery of the retrosigmoid approach to the lateral posterior fossa. RESULTS: Retrosigmoid craniotomies were performed on four latex-injected cadaver heads (eight CPAs). Microsurgical exposures were performed to identify neurovascular structures in each segment. 0° and 30° rigid endoscope lenses were subsequently introduced into each corridor and views were compared in this manner. The endoscopic images were compared with the standard microscopic views to determine the degree of visualization with each technique. In each case, better visualization was provided by both the 0° and 30° endoscope lenses. Endoscopic views frequently clarified neurovascular relationships in obscured anatomic regions. CONCLUSION: Endoscope-assisted microsurgery could allow better visualization of various regions of the posterior fossa. Surgical planning for posterior fossa lesions should include consideration of this combined approach.

16.
Cureus ; 13(8): e16955, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34513521

ABSTRACT

Introduction Systemic lupus erythematosus (SLE) is a systemic disease with clinically heterogeneous outcomes. Lupus nephritis (LN) is a common complication of SLE. LN impacts clinical SLE outcomes both directly, in the form of target organ damage, and indirectly, through the adverse effects of immunosuppressive therapy. Patients & methods The study included 402 SLE cases with biopsy-proven lupus nephritis who were under follow-up for the past 13 years at Mansoura Urology and Nephrology Center, Egypt. We studied the differences in outcome among various LN classes and between 275 proliferative cases and 102 non-proliferative cases. Results Class IV was the main LN class in our series with renal survival of 60% at 10 years. The major induction regimen after the first biopsy was cyclophosphamide. Mycophenolate mofetil was the main induction and adjunctive regimen after the second biopsy. The mean follow-up period was 6.7 + 5.2 years. Higher serum creatinine, proteinuria, activity, and chronicity indices were noted in proliferative LN. Patients suffering from proliferative lesions received higher immunosuppression and demonstrated higher morbidity than those with non-proliferative lesions. Remission was higher among the non-proliferative compared to the proliferative group. Conclusions Serum creatinine, proteinuria, and LN class were the most relevant prognostic factors for renal survival among Egyptian LN patients.

17.
J Cardiothorac Surg ; 16(1): 162, 2021 Jun 07.
Article in English | MEDLINE | ID: mdl-34099011

ABSTRACT

INTRODUCTION: Multiple studies have shown a decrease in the inflammatory response with minimized bypass circuits leading to less complications and mortality rate. On the other hand, some other studies showed that there is no difference in post-operative outcomes. So, the aim of this study is to investigate the clinical benefits of using the Minimized cardiopulmonary Bypass system in Coronary Artery Bypass Grafting and its effect on postoperative morbidity and mortality in diabetic patients as one of the high-risk groups that may benefit from these systems. METHODS: This is a retrospective study that included 114 diabetic patients who underwent Coronary artery bypass grafting (67 patients with conventional cardiopulmonary bypass system and 47 with Minimized cardiopulmonary bypass system). The patients' demographics, intra-operative characteristics and postoperative complications were compared between the two groups. RESULTS: Coronary artery bypass grafting was done on a beating heart less commonly in the conventional cardiopulmonary bypass group (44.78% vs. 63.83%, p = 0.045). There was no difference between the two groups in blood loss or transfusion requirements. Four patients in the conventional cardiopulmonary bypass group suffered perioperative myocardial infarction while no one had perioperative myocardial infarction in the Minimized cardiopulmonary bypass group. On the other hand, less patients in the conventional group had postoperative Atrial Fibrillation (4.55% vs. 27.5%, p = 0.001). The requirements for Adrenaline and Nor-Adrenaline infusions were more common the conventional group than the Minimized group. CONCLUSION: The use of conventional cardiopulmonary bypass for Coronary Artery Bypass Grafting in diabetic patients was associated with higher use of postoperative vasogenic and inotropic support. However, that did not translate into higher complications rate or mortality.


Subject(s)
Cardiopulmonary Bypass/methods , Coronary Artery Bypass/methods , Coronary Artery Disease/surgery , Diabetes Complications/surgery , Postoperative Complications/prevention & control , Adult , Aged , Coronary Artery Disease/complications , Female , Humans , Intraoperative Complications/epidemiology , Intraoperative Complications/etiology , Intraoperative Complications/prevention & control , Male , Middle Aged , Postoperative Complications/epidemiology , Postoperative Complications/etiology , Retrospective Studies , Risk Factors , Treatment Outcome
18.
J Neurosurg Pediatr ; : 1-7, 2021 Jun 11.
Article in English | MEDLINE | ID: mdl-34116509

ABSTRACT

OBJECTIVE: The goal in this study was to outline unique differences between radiation-induced and nonradiation-induced pediatric meningiomas and to identify independent risk factors of tumor recurrence/progression. METHODS: This is a retrospective cohort study of all pediatric meningiomas diagnosed and surgically treated at the authors' institution between 1993 and 2017. Multivariable Cox regression was applied to identify independent risk factors for tumor recurrence/progression. RESULTS: Thirty-five patients were identified. The primary etiology was nonradiation-induced (n = 24: n = 3 with neurofibromatosis type 2) or radiation-induced (n = 11: acute lymphoblastic leukemia [n = 5], medulloblastoma [n = 4], germ cell tumor [n = 1], and primitive neuroectodermal tumor [n = 1]) meningioma. The mean age at time of diagnosis was 10.7 ± 5.7 years for nonradiation-induced and 17.3 ± 3.5 years for radiation-induced meningiomas. Overall, 8/24 patients with nonradiation-induced meningioma experienced either recurrence or progression of the tumor. Of the 8 patients with tumor recurrence or progression, the pathological diagnosis was clear cell meningioma (n = 3: 2 recurrent and 1 progressive); grade I (n = 2 progressive); grade I with atypical features (n = 2: 1 recurrent and 1 progressive); or atypical meningioma (n = 1 recurrent). None of the patients with radiation-induced meningioma experienced recurrence or progression. Predictors of tumor recurrence/progression by univariate analysis included age at time of diagnosis ≤ 10 years (p = 0.002), histological subtype clear cell meningioma (p = 0.003), and primary etiology nonradiation-induced meningioma (p = 0.04), and there was a notable trend with elevated MIB-1 staining index (SI) (p = 0.09). There was no significant difference between nonradiation-induced and radiation-induced meningiomas (p = 0.258), although there was a trend between recurrent and nonrecurrent meningiomas (p = 0.09). Multivariate Cox regression, adjusted for length of follow-up, identified younger age at diagnosis (p = 0.004) and a higher MIB-1 SI (p = 0.044) as independent risk factors for recurrence. Elevated MIB-1 SI statistically correlated with atypia (p < 0.001). However, there was no significant statistical correlation between tumor recurrence/progression and atypia (p = 0.2). CONCLUSIONS: Younger patient age and higher MIB-1 SI are independent risk factors for recurrence. Atypia was not a predictor of recurrence.

19.
Front Neurosci ; 15: 638474, 2021.
Article in English | MEDLINE | ID: mdl-33746705

ABSTRACT

Various hypotheses of information representation in brain, referred to as neural codes, have been proposed to explain the information transmission between neurons. Neural coding plays an essential role in enabling the brain-inspired spiking neural networks (SNNs) to perform different tasks. To search for the best coding scheme, we performed an extensive comparative study on the impact and performance of four important neural coding schemes, namely, rate coding, time-to-first spike (TTFS) coding, phase coding, and burst coding. The comparative study was carried out using a biological 2-layer SNN trained with an unsupervised spike-timing-dependent plasticity (STDP) algorithm. Various aspects of network performance were considered, including classification accuracy, processing latency, synaptic operations (SOPs), hardware implementation, network compression efficacy, input and synaptic noise resilience, and synaptic fault tolerance. The classification tasks on Modified National Institute of Standards and Technology (MNIST) and Fashion-MNIST datasets were applied in our study. For hardware implementation, area and power consumption were estimated for these coding schemes, and the network compression efficacy was analyzed using pruning and quantization techniques. Different types of input noise and noise variations in the datasets were considered and applied. Furthermore, the robustness of each coding scheme to the non-ideality-induced synaptic noise and fault in analog neuromorphic systems was studied and compared. Our results show that TTFS coding is the best choice in achieving the highest computational performance with very low hardware implementation overhead. TTFS coding requires 4x/7.5x lower processing latency and 3.5x/6.5x fewer SOPs than rate coding during the training/inference process. Phase coding is the most resilient scheme to input noise. Burst coding offers the highest network compression efficacy and the best overall robustness to hardware non-idealities for both training and inference processes. The study presented in this paper reveals the design space created by the choice of each coding scheme, allowing designers to frame each scheme in terms of its strength and weakness given a designs' constraints and considerations in neuromorphic systems.

20.
J Neurosurg Pediatr ; 27(5): 548-555, 2021 Mar 05.
Article in English | MEDLINE | ID: mdl-33668031

ABSTRACT

OBJECTIVE: The goal of this study was to identify the independent risk factors for recurrence or progression of pediatric craniopharyngioma and to establish predictors of the appropriate timing of intervention and best management strategy in the setting of recurrence/progression, with the aim of optimizing tumor control. METHODS: This is a retrospective cohort study of all pediatric patients with craniopharyngioma who were diagnosed and treated at Boston Children's Hospital between 1990 and 2017. This study was approved by the institutional review board at Boston Children's Hospital. All statistical analyses were performed using Stata software. RESULTS: Eighty patients (43 males and 37 females) fulfilled the inclusion criteria. The mean age at the time of diagnosis was 8.6 ± 4.4 years (range 1.2-19.7 years). The mean follow-up was 10.9 ± 6.5 years (range 1.3-24.6 years). Overall, 30/80 (37.5%) patients developed recurrence/progression. The median latency to recurrence/progression was 12.75 months (range 3-108 months). Subtotal resection with no adjuvant radiotherapy (p < 0.001) and fine calcifications (p = 0.008) are independent risk factors for recurrence/progression. An increase (%) in the maximum dimension of the tumor at the time of recurrence/progression was considered a statistically significant predictor of the appropriate timing of intervention. CONCLUSIONS: Based on the identified independent risk factors for tumor recurrence/progression and the predictors of appropriate timing of intervention in the setting of recurrence/progression, the authors propose an algorithm for optimal management of recurrent pediatric craniopharyngioma to increase the likelihood of tumor control.


Subject(s)
Algorithms , Craniopharyngioma/therapy , Neoplasm Recurrence, Local/therapy , Pituitary Neoplasms/therapy , Adolescent , Child , Child, Preschool , Cohort Studies , Disease Progression , Female , Humans , Infant , Male , Retrospective Studies , Risk Factors , Young Adult
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