Forelimb movements contribute to hindlimb cutaneous reflexes during locomotion in cats.

During quadrupedal locomotion, interactions between spinal and supraspinal circuits and somatosensory feedback coordinate forelimb and hindlimb movements. How this is achieved is not clear. To determine whether forelimb movements modulate hindlimb cutaneous reflexes involved in responding to an external perturbation, we stimulated the superficial peroneal nerve in six intact cats during quadrupedal locomotion and during hindlimb-only locomotion (with forelimbs standing on stationary platform) and in two cats with a low spinal transection (T12-T13) during hindlimb-only locomotion. We compared cutaneous reflexes evoked in six ipsilateral and four contralateral hindlimb muscles. Results showed similar occurrence and phase-dependent modulation of short-latency inhibitory and excitatory responses during quadrupedal and hindlimb-only locomotion in intact cats. However, the depth of modulation was reduced in the ipsilateral semitendinosus during hindlimb-only locomotion. Additionally, longer-latency responses occurred less frequently in extensor muscles bilaterally during hindlimb-only locomotion, whereas short-latency inhibitory and longer-latency excitatory responses occurred more frequently in the ipsilateral and contralateral sartorius anterior, respectively. After spinal transection, short-latency inhibitory and excitatory responses were similar to both intact conditions, whereas mid- or longer-latency excitatory responses were reduced or abolished. Our results in intact cats and the comparison with spinal-transected cats suggest that the absence of forelimb movements suppresses inputs from supraspinal structures and/or cervical cord that normally contribute to longer-latency reflex responses in hindlimb extensor muscles.NEW & NOTEWORTHY During quadrupedal locomotion, the coordination of forelimb and hindlimb movements involves central circuits and somatosensory feedback. To demonstrate how forelimb movement affects hindlimb cutaneous reflexes during locomotion, we stimulated the superficial peroneal nerve in intact cats during quadrupedal and hindlimb-only locomotion as well as in spinal-transected cats during hindlimb-only locomotion. We show that forelimb movement influences the modulation of hindlimb cutaneous reflexes, particularly the occurrence of long-latency reflex responses.

Subarachnoid Hemorrhage, Delayed Cerebral Ischemia, and Milrinone Use in Canada.

INTRODUCTION: Delayed cerebral ischemia (DCI) is a complication of aneurysmal subarachnoid hemorrhage (aSAH) and is associated with significant morbidity and mortality. There is little high-quality evidence available to guide the management of DCI. The Canadian Neurosurgery Research Collaborative (CNRC) is comprised of resident physicians who are positioned to capture national, multi-site data. The objective of this study was to evaluate practice patterns of Canadian physicians regarding the management of aSAH and DCI. METHODS: We performed a cross-sectional survey of Canadian neurosurgeons, intensivists, and neurologists who manage aSAH. A 19-question electronic survey (Survey Monkey) was developed and validated by the CNRC following a DCI-related literature review (PubMed, Embase). The survey was distributed to members of the Canadian Neurosurgical Society and to Canadian members of the Neurocritical Care Society. Responses were analyzed using quantitative and qualitative methods. RESULTS: The response rate was 129/340 (38%). Agreement among respondents was limited to the need for intensive care unit admission, use of clinical and radiographic monitoring, and prophylaxis for the prevention of DCI. Several inconsistencies were identified. Indications for starting hyperdynamic therapy varied. There was discrepancy in the proportion of patients who felt to require IV milrinone, IA vasodilators, or physical angioplasty for treatment of DCI. Most respondents reported their facility does not utilize a standardized definition for DCI. CONCLUSION: DCI is an important clinical entity for which no homogeneity and standardization exists in management among Canadian practitioners. The CNRC calls for the development of national standards in the definition, identification, and treatment of DCI.

Invasive Brain Computer Interface for Motor Restoration in Spinal Cord Injury: A Systematic Review.

STUDY DESIGN: Systematic review of the literature. OBJECTIVES: In recent years, brain-computer interface (BCI) has emerged as a potential treatment for patients with spinal cord injury (SCI). This is the first systematic review of the literature on invasive closed-loop BCI technologies for the treatment of SCI in humans. MATERIALS AND METHODS: A comprehensive search of PubMed MEDLINE, Web of Science, and Ovid EMBASE was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Of 8316 articles collected, 19 studies met all the inclusion criteria. Data from 21 patients were extracted from these studies. All patients sustained a cervical SCI and were treated using either a BCI with intracortical microelectrode arrays (n = 18, 85.7%) or electrocorticography (n = 3, 14.3%). To decode these neural signals, machine learning and statistical models were used: support vector machine in eight patients (38.1%), linear estimator in seven patients (33.3%), Hidden Markov Model in three patients (14.3%), and other in three patients (14.3%). As the outputs, ten patients (47.6%) underwent noninvasive functional electrical stimulation (FES) with a cuff; one (4.8%) had an invasive FES with percutaneous stimulation, and ten (47.6%) used an external device (neuroprosthesis or virtual avatar). Motor function was restored in all patients for each assigned task. Clinical outcome measures were heterogeneous across all studies. CONCLUSIONS: Invasive techniques of BCI show promise for the treatment of SCI, but there is currently no technology that can restore complete functional autonomy in patients with SCI. The current techniques and outcomes of BCI vary greatly. Because invasive BCIs are still in the early stages of development, further clinical studies should be conducted to optimize the prognosis for patients with SCI.

Deep brain stimulation targets in epilepsy: Systematic review and meta-analysis of anterior and centromedian thalamic nuclei and hippocampus.

Deep brain stimulation (DBS) is a neuromodulatory treatment used in patients with drug-resistant epilepsy (DRE). The primary goal of this systematic review and meta-analysis is to describe recent advancements in the field of DBS for epilepsy, to compare the results of published trials, and to clarify the clinical utility of DBS in DRE. A systematic literature search was performed by two independent authors. Forty-four articles were included in the meta-analysis (23 for anterior thalamic nucleus [ANT], 8 for centromedian thalamic nucleus [CMT], and 13 for hippocampus) with a total of 527 patients. The mean seizure reduction after stimulation of the ANT, CMT, and hippocampus in our meta-analysis was 60.8%, 73.4%, and 67.8%, respectively. DBS is an effective and safe therapy in patients with DRE. Based on the results of randomized controlled trials and larger clinical series, the best evidence exists for DBS of the anterior thalamic nucleus. Further randomized trials are required to clarify the role of CMT and hippocampal stimulation. Our analysis suggests more efficient deep brain stimulation of ANT for focal seizures, wider use of CMT for generalized seizures, and hippocampal DBS for temporal lobe seizures. Factors associated with clinical outcome after DBS for epilepsy are electrode location, stimulation parameters, type of epilepsy, and longer time of stimulation. Recent advancements in anatomical targeting, functional neuroimaging, responsive neurostimulation, and sensing of local field potentials could potentially lead to improved outcomes after DBS for epilepsy and reduced sudden, unexpected death of patients with epilepsy. Biomarkers are needed for successful patient selection, targeting of electrodes and optimization of stimulation parameters.

Airway Management with Leksell Frame in situ with or without Frontal Bar: A Mannequin Study.

BACKGROUND: The use of stereotactic headframes for neurosurgical procedures requiring targeted localization continues to grow with new advancements in technology and treatment modalities. A configuration of the Leksell stereotactic G frame with a straight front bar, useful in epilepsy and laser cases, almost completely obscures oral access and presents a significant airway challenge for the anesthetist. Although previous papers have suggested that the entire headframe should be removed during an airway emergency, we describe a novel method to remove only the front bar. METHODS: We performed an observational mannequin study. Anesthesia personnel from a single center were asked to intubate a mannequin with the Leksell frame fully in situ and again with the front bar removed. In addition, the time to remove the entire frame versus only the front bar was investigated. RESULTS: Eighteen anesthesia personnel participated in the study as well as four neurosurgeons. The average time to intubate the mannequin in the frame was 23.5 (11.4) seconds and with the front bar removed, 10.9 (2.5) seconds (p < 0.001). The average time taken to remove just the front bar by the neurosurgeons was 35.4 (7.3) seconds compared to an average of 83.3 (18.6) seconds to remove the headframe entirely (p < 0.001). CONCLUSION: Our study demonstrates that intubating with the Leksell front bar in situ is possible with videolaryngoscopy under an ideal situation. More importantly, the removal of just the front bar is a simpler more streamlined approach requiring statistically less time to secure an airway.

Adoption of focused ultrasound thalamotomy for essential tremor: why so much fuss about FUS?

BACKGROUND: Focused ultrasound (FUS) was approved as a new treatment modality for essential tremor (ET) in 2016. The goal of this study was to quantify FUS adoption for ET and understand its drivers. METHODS: The adoption of the various surgical options for ET was estimated using three measures: the number of presentations on the various surgical treatments for ET at specialised international meetings, the number of original papers published as identified by literature searches and the number of thalamotomy procedures performed worldwide for ET as provided by device manufacturers' registries. RESULTS: First, we found that the number of presentations related to lesioning procedures is increasing relative to deep brain stimulation (DBS) at international meetings. Second, there are already more publications on FUS (93) than stereotactic radiosurgery (SRS) (68) or radiofrequency (43) for ET, although they still lag behind DBS papers (750). Third, the number of annual FUS thalamotomies performed for ET (n>1200 in 2019) in 44 centres has surpassed the annual procedures across 342 Gamma Knife units (n<400, 2018) but is yet to reach the number of DBS cases for ET estimated at over 2400/year. CONCLUSION: FUS is being rapidly adopted for the treatment of ET. We hypothesise that its perceived minimally invasive nature coupled with the ability to perform intraoperative clinical assessments, its immediate effects and active marketing efforts are contributing factors. As lesioning modalities for the treatment of ET are reappraised, the superior popularity of FUS over SRS appears to arise for reasons other than differences in clinical outcomes.

Bilateral Focused Ultrasound Thalamotomy for Essential Tremor (BEST-FUS Phase 2 Trial).

BACKGROUND: In patients with medically refractory essential tremor, unilateral magnetic resonance-guided focused ultrasound thalamotomy can improve contralateral tremor. However, this procedure does not address ipsilateral symptoms. OBJECTIVE: The objective of the current study was to determine whether bilateral thalamotomies can be performed with an acceptable safety profile where benefits outweigh adverse effects. METHODS: We conducted a prospective, single-arm, single-blinded phase 2 trial of second-side magnetic resonance-guided focused ultrasound thalamotomy in patients with essential tremor. Patients were followed for 3 months. The primary outcome was the change in quality of life relative to baseline, as well as the answer to the question "Given what you know now, would you treat the second side again?". Secondary outcomes included tremor, gait, speech, and adverse effects. RESULTS: Ten patients were analyzed. The study met both primary outcomes, with the intervention resulting in clinically significant improvement in quality of life at 3 months (mean Quality of Life in Essential Tremor score difference, 19.7; 95%CI, 8.0-31.4; P = 0.004) and all patients reporting that they would elect to receive the second-side treatment again. Tremor significantly improved in all patients. Seven experienced mild adverse effects, including 2 with transient gait impairment and a fall, 1 with dysarthria and dysphagia, and 1 with mild dysphagia persisting at 3 months. CONCLUSIONS: Staged bilateral magnetic resonance-guided focused ultrasound thalamotomy can be performed with a reasonable safety profile similar to that seen with unilateral thalamotomy and improves the tremor and quality of life of patients with essential tremor. Longer-term follow-up and continued accrual in the phase 3 trial will be required to validate these findings. © 2021 International Parkinson and Movement Disorder Society.

Cortical Spreading Depolarization in Chronic Subdural Hematoma: Bridging the Gap.

Cortical spreading depolarization (CSD) is recognized as a cause of transient neurological symptoms (TNS) in various clinical entities. Although scientific literature has been flourishing in the field of CSD, it remains an underrecognized pathophysiology in clinical practice. The literature evoking CSD in relation to subdural hematoma (SDH) is particularly scarce. Patients with SDH frequently suffer from TNS, most being attributed to seizures despite an atypical semiology, evolution, and therapeutic response. Recent literature has suggested that a significant proportion of those patients' TNS represent the clinical manifestations of underlying CSD. Recently, the term Non-Epileptical Stereoytpical Intermittent Symptoms (NESIS) has been proposed to describe a subgroup of patients presenting with TNS in the context of SDH. Indirect evidence and recent research suggest that the pathophysiology of NESIS could represent the clinical manifestation of CSD. This review should provide a concise yet thorough review of the current state of literature behind the pathophysiology of CSD with a particular focus on recent research and knowledge regarding the presence of CSD in the context of subdural hematoma. Although many questions remain in the evolution of knowledge in this field would likely have significant diagnostic, therapeutic, and prognostic implications.

Successful Management of Glioblastoma Chemotherapy-Associated Dysgeusia with Gabapentin.

Dysgeusia is a frequent, yet underreported side effect of chemotherapy for cancer. We report here the first use of gabapentin in two glioblastoma patients who developed dysgeusia following intra-arterial administration of carboplatin or oral administration of lomustine, respectively. Treatment initiation was followed by resolution of taste alteration within weeks. Both patients reported significant improvement in their quality of life and regained weight, allowing further chemotherapy cycles. We hypothesized that in these two cases, chemotherapy impeded gustatory cells turnover and function, resulting in a gustatory "deafferentation-like" syndrome which was successfully addressed by the medication.

Stereotactic Radiosurgery for Unruptured Versus Ruptured Pediatric Brain Arteriovenous Malformations.

Background and Purpose- The effects of prior hemorrhage on stereotactic radiosurgery (SRS) outcomes for pediatric arteriovenous malformations (AVMs) are not well defined. The aim of this multicenter, retrospective cohort study is to compare the SRS outcomes for unruptured versus ruptured pediatric AVMs. Methods- The International Radiosurgery Research Foundation pediatric AVM database from 1987 to 2018 was reviewed retrospectively. Favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes. Associations between prior hemorrhage and outcomes were adjusted for baseline differences, inverse probability weights, and competing risks. Results- The study cohort comprised 153 unruptured and 386 ruptured AVMs. Favorable outcome was achieved in 48.4% and 60.4% of unruptured and ruptured AVMs, respectively (adjusted odds ratio, 1.353; P=0.190). Cumulative AVM obliteration probabilities were 51.2%, 59.4%, 64.2%, and 70.0% for unruptured and 61.0%, 69.3%, 74.0%, and 79.3% for ruptured AVMs at 4, 6, 8, and 10 years, respectively (subhazard ratio, 1.311; P=0.020). Cumulative post-SRS hemorrhage probabilities were 4.5%, 5.6%, 5.6%, and 9.8% for unruptured and 4.7%, 6.1%, 6.1%, and 10.6% for ruptured AVMs at 4, 6, 8, and 10 years, respectively (subhazard ratio, 1.086; P=0.825). Probabilities of AVM obliteration (adjusted subhazard ratio, 0.968; P=0.850) and post-SRS hemorrhage (adjusted subhazard ratio, 1.663; P=0.251) were comparable between the 2 cohorts after inverse probability weight adjustments. Symptomatic (15.8% versus 8.1%; adjusted odds ratio, 0.400; P=0.008) and permanent (9.2% versus 5.0%; adjusted odds ratio, 0.441; P=0.045) radiation-induced change were more common in unruptured AVMs. Conclusions- The overall outcomes after SRS for unruptured versus ruptured pediatric AVMs are comparable. However, symptomatic and permanent radiation-induced change occur more frequently in pediatric patients with unruptured AVMs.

Repeat stereotactic radiosurgery for the management of locally recurrent brain metastases.

PURPOSE: Stereotactic radiosurgery (SRS) is a well-established treatment option for brain metastases (BM). Repeat SRS for progressive BM is an increasingly used paradigm, although little data is available to support this practice. The goal of this study was to assess the safety and efficacy of a second SRS procedure on a previously treated BM. METHODS: We performed a retrospective metastasis-level analysis of patients who underwent two SRS procedures on the same lesion and for whom at least 6 months of radiological follow-up was available. The data collected included patient characteristics, clinical symptoms at time of treatment, SRS parameters, radiological response per RANO-BM criteria, clinical evolution and survival. RESULTS: Seventy-five BM in 56 patients were included in the analysis. Most frequent primary histologies were non-small-cell lung cancer (59%) and breast cancer (19%). At the second SRS, median treatment volume was 1.19 cc (range 0.07-20.6) treated with a median margin dose of 18 Gy (range 12-20) at the 50% isodose line (range 30-80%). Median follow-up was 11 months. Progression per RANO-BM criteria occurred in 31%, yielding actuarial local control at 1, 2, and 5 years of 68%, 54% and 54% respectively. At last follow-up, 10 patients (18%) had improved relative to the initial presentation, while 21 (38%) were stable and 25 (44%) were deteriorated. Radiation-induced edema and radionecrosis occurred in 8.3% and 5% respectively. The median survival from the diagnosis of BM was 30 months. CONCLUSION: Repeat SRS is a safe and effective novel therapeutic approach to consider in carefully selected patients.

Psychiatric Neurosurgery: A Survey on the Perceptions of Psychiatrists and Residents.

OBJECTIVES: To evaluate the attitudes and perceptions of psychiatrists and psychiatry residents regarding neurosurgical procedures for treating psychiatric disorders and to identify potential barriers to patient referral. METHODS: A survey consisting of 25 questions was created using SurveyMonkey and was distributed to psychiatrists and psychiatry residents in Quebec. The study was approved by the McGill University Health Center's Research Ethics Board. Descriptive statistics and Friedman's test were performed using SPSS software. RESULTS: A total of 99 participants, including 64 residents and 35 psychiatrists, completed more than 75% of the survey and were included in data analysis. Overall, participants were significantly (p < 0.0005) more comfortable in referring patients suffering from treatment-resistant obsessive-compulsive disorder than from treatment-resistant major depressive disorder and preferred to refer patients for deep brain stimulation (DBS) rather than for anterior cingulotomy/capsulotomy (AC). Only 11.43% of psychiatrists had ever referred a patient for AC or DBS, and 34.69% of respondents felt that these procedures were dangerous. Lack of knowledge (82.83%) was viewed as the principal limiting factor, and 57.58% of respondents identified ≥6 different barriers to patient referral. The majority of participants (69.39%) were interested in improving their knowledge on psychiatric neurosurgery, and 82.65% felt that this subject should be included in the psychiatry residency curriculum. CONCLUSION: Overall, participants acknowledged having many limitations to referring patients for neurosurgical interventions. While informative conferences discussing neuromodulation/neuroablation could easily address many barriers, further studies are required to assess how these could change attitudes and patterns of referral.

Demographics, Interests, and Quality of Life of Canadian Neurosurgery Residents.

BACKGROUND: Neurosurgical residents face a unique combination of challenges, including long duty hours, technically challenging cases, and uncertain employment prospects. We sought to assess the demographics, interests, career goals, self-rated happiness, and overall well-being of Canadian neurosurgery residents. METHODS: A cross-sectional survey was developed and sent through the Canadian Neurosurgery Research Collaborative to every resident enrolled in a Canadian neurosurgery program as of April 1, 2016. RESULTS: We analyzed 76 completed surveys of 146 eligible residents (52% response rate). The median age was 29 years, with 76% of respondents being males. The most popular subspecialties of interest for fellowship were spine, oncology, and open vascular neurosurgery. The most frequent self-reported number of worked hours per week was the 80- to 89-hour range. The majority of respondents reported a high level of happiness as well as stress. Sense of accomplishment and fatigue were reported as average to high and overall quality of life was low for 19%, average for 49%, and high for 32%. Satisfaction with work-life balance was average for 44% of respondents and was the only tested domain in which significant dissatisfaction was identified (18%). Overall, respondents were highly satisfied with their choice of specialty, choice of program, surgical exposure, and work environment; however, intimidation was reported in 36% of respondents and depression by 17%. CONCLUSIONS: Despite a challenging residency and high workload, the majority of Canadian neurosurgery residents are happy and satisfied with their choice of specialty and program. However, work-life balance, employability, resident intimidation, and depression were identified as areas of active concern.

Prognostic significance of corticotroph staining in radiosurgery for non-functioning pituitary adenomas: a multicenter study.

Silent corticotroph staining pituitary adenoma (SCA) represents an uncommon subset of Non-Functioning adenomas (NFAs), hypothesized to be more locally aggressive. In this retrospective multicenter study, we investigate the safety and effectiveness of Stereotactic Radiosurgery (SRS) in patients with SCA compared with other non-SCA NFA's. Eight centers participating in the International Gamma-Knife Research Foundation (IGKRF) contributed to this study. Outcomes of 50 patients with confirmed SCAs and 307 patients with confirmed non-SCA NFA's treated with SRS were evaluated. Groups were matched. SCA was characterized by a lack of clinical evidence of Cushing disease, yet with positive immunostaining for corticotroph. Median age was 55.2 years (13.7-87). All patients underwent at least one trans-sphenoidal tumor resection prior to SRS. SRS parameters were comparable as well. Median follow-up 40 months (6-163). Overall tumor control rate (TCR) 91.2% (n = 280). In the SCA group, TCR were 82% (n = 41) versus 94.1% (n = 289) for the control-NFA (p = 0.0065). The SCA group showed a significantly higher incidence of new post-SRS visual deficit (p < 0.0001) assigned to tumor progression and growth, and post-SRS weakness and fatigue (p < 0.0001). In univariate and multivariate analysis, only the status of silent corticotroph staining (p = 0.005, p = 0.009 respectively) and margin dose (p < 0.0005, p = 0.0037 respectively) significantly influenced progression rate. A margin dose of ≥17 Gy was noted to influence the adenoma progression rate in the entire cohort (p = 0.003). Silent corticotroph staining represents an independent factor for adenoma progression and hypopituitarism after SRS. A higher margin dose may convey a greater chance of TCR.

Operative Landscape at Canadian Neurosurgery Residency Programs.

Background Currently, the literature lacks reliable data regarding operative case volumes at Canadian neurosurgery residency programs. Our objective was to provide a snapshot of the operative landscape in Canadian neurosurgical training using the trainee-led Canadian Neurosurgery Research Collaborative. METHODS: Anonymized administrative operative data were gathered from each neurosurgery residency program from January 1, 2014, to December 31, 2014. Procedures were broadly classified into cranial, spine, peripheral nerve, and miscellaneous procedures. A number of prespecified subspecialty procedures were recorded. We defined the resident case index as the ratio of the total number of operations to the total number of neurosurgery residents in that program. Resident number included both Canadian medical and international medical graduates, and included residents on the neurosurgery service, off-service, or on leave for research or other personal reasons. RESULTS: Overall, there was an average of 1845 operative cases per neurosurgery residency program. The mean numbers of cranial, spine, peripheral nerve, and miscellaneous procedures were 725, 466, 48, and 193, respectively. The nationwide mean resident case indices for cranial, spine, peripheral nerve, and total procedures were 90, 58, 5, and 196, respectively. There was some variation in the resident case indices for specific subspecialty procedures, with some training programs not performing carotid endarterectomy or endoscopic transsphenoidal procedures. CONCLUSIONS: This study presents the breadth of neurosurgical training within Canadian neurosurgery residency programs. These results may help inform the implementation of neurosurgery training as the Royal College of Physicians and Surgeons residency training transitions to a competence-by-design curriculum.

Improving the pedagogical effectiveness of medical videos.

Videos are often employed in medical cursus, yet few guidelines are available to help with their production. Mayer's cognitive theory of multimedia learning is the most cited evidence-based framework for improving pedagogical effectiveness of multimedia content. Based on this framework, we identified four workflow interventions to improve the effectiveness of video content in the context of medical education: (1) choosing appropriate content; (2) optimizing the voiceover; (3) optimizing the supporting visuals and (4) planning the shooting schedule in advance. Content creators should think about pedagogical effectiveness and aim to improve their work by applying evidence-based principles.

Post-radiosurgical edema associated with parasagittal and parafalcine meningiomas: a multicenter study.

Stereotactic radiosurgery (SRS) offers a high degree of tumor control for benign meningiomas. However, radiosurgery can occasionally incite edema or exacerbate pre-existing peri-tumoral edema. The current study investigates the incidence, timing, and extent of edema around parasagittal or parafalcine meningiomas following SRS. A retrospective multicenter review was undertaken through participating centers in the International Gamma Knife Research Foundation (previously the North American Gamma Knife Consortium or NAGKC). All included patients had a parafalcine or parasagittal meningioma and a minimum of 6 months follow up. The median follow up was 19.6 months (6-158 months). Extent of new or worsening edema was quantitatively analyzed using volumetric analysis; edema indices were longitudinally computed following radiosurgery. Analysis was performed to identify prognostic factors for new or worsening edema. A cohort of 212 patients comprised of 51.9 % (n = 110) females, 40.1 % upfront SRS and 59.9 % underwent adjuvant SRS for post-surgical residual tumor. The median tumor volume at SRS was 5.2 ml. Venous sinus compression or invasion was demonstrated in 25 % (n = 53). The median marginal dose was 14 Gy (8-20 Gy). Tumor volume control was determined in 77.4 % (n = 164 out of 212 patients). Tumor edema progressed and then regressed in 33 % (n = 70), was stable or regressed in 52.8 % (n = 112), and progressively worsened in 5.2 % (n = 11). Tumor location, tumor volume, venous sinus invasion, margin, and maximal dose were found to be significantly related to post-SRS edema in multivariate analysis. SRS affords a high degree of tumor control for patients with parasagittal or parafalcine meningiomas. Nevertheless, SRS can lead to worsening peritumoral edema in a subset of patients such as those with larger tumors (>10 cc) and venous sinus invasion/compression. Long-term follow up is required to detect and appropriately manage post-SRS edema.

A Practical Roadmap to Implementing Deep Learning Segmentation in the Clinical Neuroimaging Research Workflow.

Thanks to the proliferation of open-source tools, we are seeing an exponential growth of machine learning applications, and its integration has become more accessible, particularly for segmentation tools in neuroimaging. This article explores a generalised methodology that harnesses these tools and aims/enables to expedite and enhance the reproducibility of clinical research. Herein, critical re considerations include hardware, software, neural network training strategies and data labelling guidelines. More specifically, we advocate an iterative approach to model training and transfer learning, focusing on internal validation and outlier handling early in the labelling process and fine-tuning later on. The iterative refinement process allows experts to intervene and improve model reliability whilst cutting down on their time spent in manual work. A seamless integration of the final model's predictions into clinical research is proposed to ensure standardized and reproducible results. In short, this article provides a comprehensive framework for accelerating research using machine learning techniques for image segmentation.