Chiari type III malformation associated with Klippel-Feil syndrome, a case report with a narrative review of the literature.

BACKGROUND: Chiari malformation type III (CM III), a rare hindbrain anomaly, often presents with various concurrent anomalies. This paper reports a unique case of CM III associated with Klippel-Feil syndrome (KFS), a condition previously unreported in Saudi Arabia and documented in only one other case globally in Turkey. This study aims to share insights into the unusual association between CM III and KFS, considering their close embryological development and involvement in the craniocervical junction. METHODOLOGY: The study presents a case of a 2.5-year-old female diagnosed with CM III and KFS. Diagnostic tools such as ultrasound, CT scans, MRI, and physical examinations were used to confirm the patient's condition. Surgical interventions, including decompression and encephalocele repair, were performed. RESULTS: Successful surgical interventions, including encephalocele repair and duraplasty, were carried out. Follow-up visits indicated a stable condition, marked improvement in lower limb strength, and the patient's ability to walk with assistance. CT follow-up affirmed a satisfactory surgical outcome. CONCLUSION: This case study illustrates the potential for an optimistic prognosis in CM III, even when accompanied by complex conditions such as KFS, through early diagnosis and intervention. It underscores the significance of antenatal screening for effective care planning and calls for further research and publications due to the rarity of this association. These findings contribute to our understanding of CM III and its related conditions, emphasizing the need for open-minded consideration of potential embryological associations.

Complications and visual outcomes following surgical resection of pediatric optic pathway/hypothalamic gliomas: a systematic review and meta-analysis.

Pediatric optic pathway/hypothalamic gliomas (OPHG) pose challenges in treatment due to their location and proximity to vital structures. Surgical resection plays a key role in the management of OPHG especially when the tumor exhibits mass effect and causes symptoms. However, data regarding outcomes and complications of surgical resection for OPHG remains heterogenous. The authors performed a systematic review on pediatric OPHG in four databases: PubMed, EMBASE, Cochrane Library, and Google Scholar. We included studies that reported on the visual outcomes and complications of OPHG resection. A meta-analysis was performed and reported per the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. A total of 26 retrospective studies were included. Seven hundred ninety-seven pediatric patients with OPHG undergoing surgical resection were examined. A diagnosis of NF1 was confirmed in 9.7%. Gross total resection was achieved in 36.7%. Intraorbital optic pathway gliomas showed a significantly higher gross total resection rate compared to those located in the chiasmatic/hypothalamic region (75.8% vs. 9.6%). Postoperatively, visual acuity improved in 24.6%, remained unchanged in 68.2%, and worsened in 18.2%. Complications included hydrocephalus (35.4%), anterior pituitary dysfunction (19.6%), and transient diabetes insipidus (29%). Tumor progression post-resection occurred in 12.8%, through a mean follow-up of 53.5 months. Surgical resection remains an essential strategy for treating symptomatic and large pediatric OPHG and can result in favorable vision outcomes in most patients. Careful patient selection is critical. Patients should be monitored for hydrocephalus development postoperatively and followed up to assess for tumor progression and adjuvant treatment necessity.

Dynamic interplay between corticosteroid treatment and the role of SRC-1 gene dysregulation in the progression of WHO-Grade 4 Astrocytoma.

BACKGROUND: Corticosteroid is commonly used before surgery to control cerebral oedema in brain tumours and is frequently continued throughout treatment. Its long-term effect of on the recurrence of WHO-Grade 4 astrocytoma remains controversial. The interaction between corticosteroid, SRC-1 gene and cytotoxic T-cells has never been investigated. METHODS: A retrospective cohort of 36 patients with WHO-Grade 4 astrocytoma were examined for CD8 + T-cell and SRC-1 gene expressions through IHC and qRT-PCR. The impact of corticosteroid on CD8+T-cells infiltration, SRC-1 expression, and tumour recurrence was analyzed. RESULTS: The mean patients age was 47-years, with a male to female ratio 1.2. About 78% [n = 28] of the cases showed reduced or no CD8+T-cell expression while 22% [n = 8] of cases have showed medium to high CD8+T-cell expression. SRC-1 gene was upregulated in 5 cases [14%] and 31 cases [86%] showed SRC-1 downregulation. The average of total days and doses of administered corticosteroid from the preoperative period to the postoperative period was at range of 14-106 days and 41-5028 mg, respectively. There was no significant statistical difference in RFI among tumours expressing high or low CD8+T-cells when corticosteroid was administered in recommended or exceeded doses [p-value = 0.640]. There was a significant statistical difference in RFI between CD8+T-Cell expression and SRC-1 gene dysregulation [p-value = 002]. Tumours with high CD8+T T-cell expression and SRC-1 gene downregulation had late recurrence. CONCLUSIONS: Corticosteroid treatment can directly affect the SRC-1 gene regulation but does not directly influence cytotoxic T-cells infiltration or tumor progression. However, SRC-1 gene downregulation can facilitate late tumor recurrence.

Outcomes after laser interstitial thermal ablation for temporal lobe epilepsy: a systematic review and meta-analysis.

Epilepsy is a common condition that affects approximately 1% of the world's population, with about one-third being refractory epilepsy. Temporal lobe epilepsy is the most common type of drug-resistant epilepsy, and laser interstitial thermal therapy (LITT) is an innovative treatment. In this systematic review and meta-analysis, we aimed to summarize the current evidence on outcomes after LITT, including seizure freedom rate, complication rate, and neurocognitive outcome. PubMed and OVID Medline search engines were systematically searched for all indexed publications in the English language up to July15, 2023. The search was limited to human studies. Proportions and 95% confidence interval (CI) values were calculated for seizure, neurocognitive outcome, and complication rate. A total of 836 patients were included. Overall seizure outcomes, regardless of the pathology, included Engel I outcome in 56% (95% CI, 52.4-59.5%), Engel II outcome in 19.2% (95% CI, 15.4-23.6%), Engel III outcome in 17.3% (95% CI, 13.5-21.8%), and Engel IV outcome in 10.5% (95% CI 6.3-17%) of the patients. The overall decline in verbal and visual memory regardless of laterality was 24.2 (95% CI 8.6-52%) and 25.2% (8.3-55.8%). For naming, the decline was 13.4% (6.6-25.4%). The results of the pooled analysis in comparison with available data in the literature showed that seizure outcomes after LITT were slightly inferior to published data after temporal lobectomy. Data on cognitive outcomes after LITT are scarce and heterogeneous.

Ventriculoperitoneal shunt-associated abdominal cerebrospinal fluid pseudocysts and the role of laparoscopy and a proposed management algorithm in its treatment. A report of 2 cases.

Abdominal cerebrospinal fluid pseudocyst (APC) is a rare complication associated with a ventriculoperitoneal shunt (VPS) placement. Abdominal cerebrospinal fluid pseudocyst is defined as a cyst surrounded by a non-epithelial lining and filled with the cerebrospinal fluid (CSF). In general, 1% - 4.5% of all patients treated with a VPS develop CSF pseudocysts. Here, we have presented 2 cases of APC complicating VPS placement and a proposed treatment management algorithm. The cases pertained to 7-year-old and 5-year-old children who had undergone VPS placement during infancy and presented with progressive abdominal distention and vomiting and fever, respectively. Both cases were assessed using similar investigations and imaging modalities and diagnosed with APC. However, the treatments were individually tailored based on the algorithm; successful outcomes were achieved in both patients. Abdominal cerebrospinal fluid pseudocyst treatment is difficult considering the presence of adhesions and infection and is associated with a high recurrence rate.

Electrocardiographic changes following intracranial haemorrhage: a retrospective cohort study.

OBJECTIVE: To improve the understanding of the association between electrocardiographic (ECG) abnormalities and clinical outcomes of patients with all types of intracranial hemorrhage (ICH). METHODS: A retrospective cohort study was conducted in a tertiary healthcare hospital on patients with ICH without cardiac disease or renal disease requiring dialysis. Demographic and clinical data were collected from hospital records. ECG record were obtained within 24 hours of presentation and prior to treatment. Records were interpreted for this study by a cardiologist blinded to other data. RESULTS: Assessment of 291 patients (228 adults and 63 children) showed that subdural hemorrhage was the most common type of ICH (31.6%) followed by intraparenchymal hemorrhage (23.0%). ECG records were available for 98 patients. ECG abnormalities were most commonly nonspecific ST-segment changes (32.6%). In adults, history of neurological disease was associated with atrioventricular block (p=.004) and QTc prolongation (p=.041). Pediatric patients exhibited associations between ST-segment changes (p=.045) and sinus tachycardia (p=.027) and type of ICH. However, ECG changes were not statistically associated with clinical outcomes in adults or children. CONCLUSION: Significant ECG changes frequently occurred in patients with all types of ICH but did not consistently predict the outcome in this study. Close observation of patients is still recommended to detect ECG changes that could affect the treatment.

Evaluating the initial impact of the Riyadh Epilepsy Awareness Campaign.

OBJECTIVE: We determine the impact of an educational awareness campaign on the level of knowledge and the attitude of the Saudi population in Riyadh, Saudi Arabia in an attempt to improve the awareness and reduce the social stigma associated with epilepsy. METHODS: The Saudi Epilepsy Society organized a citywide awareness campaign in 2013. A survey consisting of 11 questions pertaining to epilepsy awareness was distributed to Saudi citizens living in Riyadh, aged 15 years and above, in malls, health clubs, mosques, universities, and schools during that campaign. The same questionnaire was administered before and after the awareness campaign to the same individuals on the same day to assess the impact of the campaign (n=2118). RESULTS: The epilepsy awareness campaign significantly raised the general knowledge about epilepsy: 1519 before vs. 1944 after (P<0.001) would allow their children to interact with an individual who had epilepsy; 1567 before vs. 688 after (P<0.001) would not want their children to marry an individual with epilepsy. Eight hundred twenty six before vs. 47 after (P<0.001) thought that epilepsy is untreatable. Regarding the causes of epilepsy, 1663 before vs. 896 after (P<0.001) believed that epilepsy is caused by supernatural powers, and 1224 before vs. 1874 after (P<0.001) chose brain disease as a cause of epilepsy. CONCLUSION: These findings suggest that epilepsy awareness campaigns can close knowledge gaps. A long-term reevaluation may be needed to assess awareness sustainability.

Focal brainstem gliomas. Advances in intra-operative management.

Improved neuronavigation guidance as well as intraoperative imaging and neurophysiologic monitoring technologies have enhanced the ability of neurosurgeons to resect focal brainstem gliomas. In contrast, diffuse brainstem gliomas are considered to be inoperable lesions. This article is a continuation of an article that discussed brainstem glioma diagnostics, imaging, and classification. Here, we address open surgical treatment of and approaches to focal, dorsally exophytic, and cervicomedullary brainstem gliomas. Intraoperative neuronavigation, intraoperative neurophysiologic monitoring, as well as intraoperative imaging are discussed as adjunctive measures to help render these procedures safer, more acute, and closer to achieving surgical goals.

Pediatric brainstem tumors. Classifications, investigations, and growth patterns.

Brainstem gliomas occur in 10-20% of brain tumors in pediatrics. Over the past 3 decades, the treatment of brainstem gliomas has significantly progressed as a result of the gradual advancements in microsurgical techniques, sophisticated imaging technology and, most importantly, the availability of MRI. In this article, we review the current literature on brainstem gliomas and cover diagnosis, imaging, classification, and management. Surgical approaches and intraoperative modalities to tackle operable cases of brainstem gliomas will be discussed in a follow up article.

Intracranial Infantile Hemangioma: Highlighting a Rare Presentation With a Case Report and Literature Review.

Infantile hemangioma is a common benign vascular tumor in children, but it is very unusual to be found intracranially. Our literature review identified 44 reported cases. Presentation can vary from asymptomatic to a life-threatening presentation that necessitates urgent surgical removal. There is no general consensus on management of these rare lesions and until recently, treatment was limited to surgery or pharmacological management with steroids, propranolol or interferon. We present a case of a four-week-old male infant with history of vomiting and increase in head circumference since birth. MRI of the brain revealed a large complex cyst occupying the right frontoparietal region, with round soft tissue component that is isointense on T1 and hyperintense on T2 weighted images. Complete surgical resection with evacuation of the cyst was achieved. Histopathology of the mass showed infantile hemangioma with positive CD31 on immunohistochemistry. The patient achieved an excellent outcome following surgical resection.

Epilepsy: What do health-care professionals in Riyadh know?

PURPOSE: The objective of this study was to report on the knowledge of epilepsy, as well as attitudes and practices toward individuals with epilepsy, among health-care professionals in Riyadh, the capital city of Saudi Arabia. METHODS: A survey consisting of 23 questions pertaining to epilepsy awareness was distributed to health education workers (n=51), nutritionists (n=56), physicians (n=265), dentists (n=58), pharmacists (n=41), nurses (n=224), physiotherapists (n=65), and fifth-year medical students (n=62) in three tertiary hospitals in Riyadh. RESULTS: Of the 822 respondents who completed the questionnaire, 100% had heard about epilepsy, and 92.6% would allow their children to interact with an individual who has epilepsy. However, 67% of respondents would not want their children to marry an individual with epilepsy, 97.9% of respondents believed that individuals with epilepsy should have the same employment opportunities as the general population, 10.5% believe that supernatural power is the cause of epilepsy, 67.2% did not know how to deal with an individual experiencing an epileptic episode, and 56% did not know that surgery was a treatment option for individuals with epilepsy in Saudi Arabia. Of the 822 respondents, 39% would not abide by a physician's advice not to operate a motor vehicle because of their illness, 91% of whom cited problems with the public transportation system as a reason for disregarding the doctor's advice. When asked if the participants had access to any information on how to deal with epilepsy during their professional training, 60.3% had access to such information during their graduate studies. Ninety-eight percent of those with access to this information were physicians and health-care educators (p<0.001). Physicians and health-care educators were significantly more aware of epilepsy than any of the other groups. CONCLUSION: The level of epilepsy awareness among health-care professionals in Riyadh needs improvement.

Utilizing artificial intelligence and electroencephalography to assess expertise on a simulated neurosurgical task.

Virtual reality surgical simulators have facilitated surgical education by providing a safe training environment. Electroencephalography (EEG) has been employed to assess neuroelectric activity during surgical performance. Machine learning (ML) has been applied to analyze EEG data split into frequency bands. Although EEG is widely used in fields requiring expert performance, it has yet been used to classify surgical expertise. Thus, the goals of this study were to (a) develop an ML model to accurately differentiate skilled and less-skilled performance using EEG data recorded during a simulated surgery, (b) explore the relative importance of each EEG bandwidth to expertise, and (c) analyze differences in EEG band powers between skilled and less-skilled individuals. We hypothesized that EEG recordings during a virtual reality surgery task would accurately predict the expertise level of the participant. Twenty-one participants performed three simulated brain tumor resection procedures on the NeuroVR™ platform (CAE Healthcare, Montreal, Canada) while EEG data was recorded. Participants were divided into 2 groups. The skilled group was composed of five neurosurgeons and five senior neurosurgical residents (PGY4-6), and the less-skilled group was composed of six junior residents (PGY1-3) and five medical students. A total of 13 metrics from EEG frequency bands and ratios (e.g., alpha, theta/beta ratio) were generated. Seven ML model types were trained using EEG activity to differentiate between skilled and less-skilled groups. The artificial neural network achieved the highest testing accuracy of 100% (AUROC = 1.0). Model interpretation via Shapley analysis identified low alpha (8-10 Hz) as the most important metric for classifying expertise. Skilled surgeons displayed higher (p = 0.044) low-alpha than the less-skilled group. Furthermore, skilled surgeons displayed significantly lower TBR (p = 0.048) and significantly higher beta (13-30 Hz, p = 0.049), beta 1 (15-18 Hz, p = 0.014), and beta 2 (19-22 Hz, p = 0.015), thus establishing these metrics as important markers of expertise. ACGME CORE COMPETENCIES: Practice-Based Learning and Improvement.

The synergistic effect of IDH mutation and NDRG-2 dysregulation in the progression of WHO-grade 4 astrocytomas.

BACKGROUND: NDRG2 is a tumour suppressor gene involved in tumor growth inhibition. Its effect on tumour recurrence remains controversial. The aim of this study is to explore the dual effect of IDH mutation and NDRG2 dysregulation in WHO-Grade 4 astrocytoma recurrence. METHODS: A group of 36 patients with WHO-Grade 4 astrocytoma were examined for NDRG2 expression using protein and gene expression assays. The relationship between IDH, NDRG2 protein and gene expressions, and recurrence-free interval [RFI] was explored. RESULTS: The mean patients age in this study was 45-years with 21 males and 15 females. IDH was mutant in 22 tumors. NDRG2 protein expression was low in 23 tumors, and high in 13 tumors. NDRG2 gene expression was upregulated in 4 tumors and 32 tumors showed NDRG2 gene downregulation. The consistency between two tasting methods of NDRG2 expression was 52.8%. There was a significant statistical difference in RFI among tumors with varying NDRG2 gene expression and IDH mutation [p-value= 0.021]. IDH-mutant tumours with downregulated NDRG2 expression showed late recurrence compared to IDH-wildtype glioblastoma. CONCLUSIONS: IDH-mutant WHO Grade-4 astrocytoma with downregulated NDRG2 gene are associated with late tumor recurrence. IDH mutations cause excessive accumulation of D-2-hydroxyglutarate, that may inhibit the activity of TET proteins, potentially leading to DNA hypermethylation and gene silencing.

Vasospasm following brain tumor resection in children: institutional experience and systematic review.

OBJECTIVE: Delayed cerebral ischemia (DCI) associated with vasospasm is well described in the setting of aneurysmal subarachnoid hemorrhage (SAH). In addition, DCI is very infrequently encountered in patients who have undergone resection of a brain tumor with unclear pathophysiology. The occurrence of DCI in the pediatric population is exceedingly rare, and outcomes in this population have, to the authors' knowledge, never been systematically reviewed. Therefore, the authors present what is to their knowledge the largest series of pediatric patients with this complication and systematically reviewed the literature for individual participant data. METHODS: The authors conducted a retrospective review of 172 sellar and suprasellar tumors in pediatric patients who underwent surgery at the Montreal Children's Hospital between 1999 and 2017 to identify cases of vasospasm occurring after tumor resection. Descriptive statistics, including patient characteristics, intraoperative and postoperative findings, and outcome status, were collected. A systematic review was also conducted using three databases (PubMed, Web of Science, Embase) to identify reported cases available in the literature of vasospasm after tumor resection in children and collect individual participant data on these patients for further analysis. RESULTS: Six patients treated at Montreal Children's Hospital were identified, with an average age of 9.5 years (range 6-15 years). The prevalence of vasospasm after tumor resection was 3.5% (6/172). Vasospasm in all 6 patients occurred after craniotomy was performed to treat a suprasellar tumor. The average interval from surgery to symptoms was 3.25 days (range 12 hours-10 days). The most common tumor etiology was craniopharyngioma, seen in 4 cases. Extensive tumor encasement of blood vessels requiring significant operative manipulation was described in all 6 patients. A rapid decrease in serum sodium (exceeding 12 mEq/L/24 hrs or below 135 mEq/L) was seen in 4 patients. On final follow-up, 3 patients were left with significant disability, and all patients had persistent deficits. A systematic review of the literature revealed a total of 10 other patients whose characteristics and treatment were compared with those of the 6 patients treated at Montreal Children's Hospital. CONCLUSIONS: Vasospasm after tumor resection in children and youth is likely a rare entity, with a prevalence of 3.5% in this case series. Suprasellar tumor location (particularly craniopharyngioma tumor etiology), significant encasement of blood vessels by the tumor, and postoperative hyponatremia may be predictive factors. Outcome is poor, with most patients having significant persistent neurological deficits.

Major Histocompatibility Class-I (MHC-I) downregulation in glioblastoma is a poor prognostic factor but not a predictive indicator for treatment failure.

BACKGROUND: MHC-I expression is a crucial factor in cancer immunity, and its regulations can impact tumor progression and recurrence. The mechanism through which glioblastoma use MHC-I to avoid immunosurveillance has been rarely investigated. METHODS: A retrospective cohort of 35 patients with IDH-mutant WHO-Grade 4 astrocytoma and IDH-wildtype glioblastoma were examined for MHC-I using protein and gene expression assays. The association between IDH mutation, TP53 mutation, and MHC-I expression with recurrence-free interval were investigated. RESULTS: The average patients' age was 49.6 year. IDH was wildtype in 13 tumors. MHC-I protein expression was absent in 30 tumors, faint in 4 tumors, and membrane bound dense expression in single tumor. MHC-I expression was upregulated in 10 tumors and 25 tumors showed MHC-I downregulation. P53 was positively expressed in 19 cases and lost in 13 cases. A significant statistical difference was observed in the RFI between tumors with distinct MHC-I expression and IDH-mutation [p-value = 0.008]. IDH-wildtype tumors with upregulated MHC-I expression showed late tumor recurrence compared to IDH-wildtype tumors with downregulated MHC-I expression. There was insignificant statistical difference in RFI among patients with varying degree of MHC-I expression, who received TMZ or TMZ and other chemotherapies [P-value = 0.44] CONCLUSIONS: Glioblastoma with upregulated MHC-I showed a delayed tumor recurrence in comparison to those with downregulated MHC-I expression. However, downregulated MHC-I may not necessarily be an indicator of poor problems.

Hemisensory Loss after Ventriculoperitoneal Shunt Insertion.

Idiopathic intracranial hypertension includes ventriculoperitoneal shunt (VPS) insertion, with a reported complication of shunt revision in 25% of the cases 1 year after insertion. We report a case of a 28-year-old female with pituitary adenoma who developed sensory loss after VPS placement that could be explained by disruption in thalamic pathways. A lesson learned from this case is that although VPS is a simple procedure, complications can occur. Modalities can be used to detect the complications, and further revisions might be needed.

Pattern of neurosurgical practice at a university hospital in KSA during COVID-19 pandemic.

Objective: The coronavirus disease 2019 (COVID-19) pandemic affected both medical services as well as hospital admissions. Scholars have attempted to study the effect of the pandemic on the services of multiple specialities. In this study, we aim to examine the pandemic's impact on the neurosurgical service provided at the King Abdulaziz University Hospital in Jeddah over an eight-month period. Methods: In this retrospective, single-centre case series study, we included all the consecutive neurosurgical patients who underwent a surgical intervention in the 8-month period starting on 3rd March, 2020 and ending on 3rd November, 2020. The demographics, diagnosis, surgery type, priority category, and mortality data of the patients were collected. Results: A total of 147 patients underwent surgery during the study period. The mean age was 30.8 years. Forty-nine percent of the study population were men. Oncology (31.3%) and hydrocephalus (23.8%) recorded the highest number of cases. More than half of the cases were Priority 1 (immediate and within 24 h). The mortality rate was 4.1% among all the performed cases. Conclusion: By describing this local neurosurgical experience during the COVID-19 pandemic, we hope to bring out some of the difficulties we encountered and improve what we learned during the pandemic.

Assessment of learning curves on a simulated neurosurgical task using metrics selected by artificial intelligence.

OBJECTIVE: Understanding the variation of learning curves of experts and trainees for a given surgical procedure is important in implementing formative learning paradigms to accelerate mastery. The study objectives were to use artificial intelligence (AI)-derived metrics to determine the learning curves of participants in 4 groups with different expertise levels who performed a series of identical virtual reality (VR) subpial resection tasks and to identify learning curve differences among the 4 groups. METHODS: A total of 50 individuals participated, 14 neurosurgeons, 4 neurosurgical fellows and 10 senior residents (seniors), 10 junior residents (juniors), and 12 medical students. All participants performed 5 repetitions of a subpial tumor resection on the NeuroVR (CAE Healthcare) platform, and 6 a priori-derived metrics selected using the K-nearest neighbors machine learning algorithm were used to assess participant learning curves. Group learning curves were plotted over the 5 trials for each metric. A mixed, repeated-measures ANOVA was performed between the first and fifth trial. For significant interactions (p < 0.05), post hoc Tukey's HSD analysis was conducted to determine the location of the significance. RESULTS: Overall, 5 of the 6 metrics assessed had a significant interaction (p < 0.05). The 4 groups, neurosurgeons, seniors, juniors, and medical students, showed an improvement between the first and fifth trial on at least one of the 6 metrics evaluated. CONCLUSIONS: Learning curves generated using AI-derived metrics provided novel insights into technical skill acquisition, based on expertise level, during repeated VR-simulated subpial tumor resections, which will allow educators to develop more focused formative educational paradigms for neurosurgical trainees.

Nondominant Hand Skills Spatial and Psychomotor Analysis During a Complex Virtual Reality Neurosurgical Task-A Case Series Study.

BACKGROUND: Virtual reality surgical simulators provide detailed psychomotor performance data, allowing qualitative and quantitative assessment of hand function. The nondominant hand plays an essential role in neurosurgery in exposing the operative area, assisting the dominant hand to optimize task execution, and hemostasis. Outlining expert-level nondominant hand skills may be critical to understand surgical expertise and aid learner training. OBJECTIVE: To (1) provide validity for the simulated bimanual subpial tumor resection task and (2) to use this simulation in qualitative and quantitative evaluation of nondominant hand skills for bipolar forceps utilization. METHODS: In this case series study, 45 right-handed participants performed a simulated subpial tumor resection using simulated bipolar forceps in the nondominant hand for assisting the surgery and hemostasis. A 10-item questionnaire was used to assess task validity. The nondominant hand skills across 4 expertise levels (neurosurgeons, senior trainees, junior trainees, and medical students) were analyzed by 2 visual models and performance metrics. RESULTS: Neurosurgeon median (range) overall satisfaction with the simulated scenario was 4.0/5.0 (2.0-5.0). The visual models demonstrated a decrease in high force application areas on pial surface with increased expertise level. Bipolar-pia mater interactions were more focused around the tumoral region for neurosurgeons and senior trainees. These groups spent more time using the bipolar while interacting with pia. All groups spent significantly higher time in the left upper pial quadrant than other quadrants. CONCLUSION: This work introduces new approaches for the evaluation of nondominant hand skills which may help surgical trainees by providing both qualitative and quantitative feedback.