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Analysis of neurosurgery resident research activity in the United States

Rita Vought, Victoria Vought, Antonia Sames, Shrey Shah, Amanda Bosland, Marco Petrozzino, Ava Herzog, and James K. Liu

OBJECTIVE

Evaluation of the demographic and academic characteristics of current neurosurgery residents may provide prospective students with insight into factors that affect research output. Therefore, this study aimed to evaluate the research output among neurosurgery residents.

METHODS

US neurosurgery residency programs were abstracted from the American Association of Neurological Surgeons website. Demographic data on 1690 current residents across 119 programs were collected using publicly available institutional websites, Doximity, and LinkedIn. The h-index of each resident was recorded using Scopus and exported into the NIH iCite tool to determine the weighted relative citation ratio (w-RCR) and mean relative citation ratio (m-RCR). The total number of publications, h-index, and w-RCR were used as a proxy for research output, while m-RCR was used to measure research impact. One-way ANOVA and Kruskal-Wallis H-tests were used to assess the statistical significance of relationships between demographic data and measures of research activity.

RESULTS

A total of 1690 residents (25.4% female), representing 119 programs, were evaluated. Neurosurgery residents had an average of 17 publications, h-index of 5.5, m-RCR of 1.4, and w-RCR of 16.9, with an upward trend of research activity by postgraduate year (PGY) class. Male residents on average had a greater total number of publications (p < 0.001), higher h-index (p < 0.001), and higher w-RCR (p = 0.002) compared with their female peers. Significant differences in research activity were also observed by degree (Doctor of Medicine [MD], Doctor of Osteopathy [DO], or other), where those with MD and other degrees had higher metrics than those with DO degrees. International medical graduates (IMGs) also had higher research output than American medical graduates (AMGs) (p < 0.001). Differences in all measures of research activity except impact were also observed in research activity when pre-residency medical school ranks were compared.

CONCLUSIONS

The authors observed overall high research activity among neurosurgery residents. Factors such as gender, degree, PGY, IMG/AMG status, and medical school rank may therefore be related to the success of matching within neurological surgery. Although large disparities in gender representation have been identified in neurosurgery, newer classes are trending toward shrinking the gap. These data may be used by prospective residents to gauge changes and progress occurring in the neurosurgery match.

Restricted access

Microsurgical anatomy of the olfactory filaments in the nasal mucosa

Hasan Barış Ilgaz, Kamran Urgun, Ulaş Yener, Melike Mut, James K. Liu, and Kaan Yağmurlu

OBJECTIVE

The aim of this study was to examine the distribution of olfactory filaments (OFs) in the nasal mucosa to facilitate preservation of olfactory function in endonasal approaches and preparation of a nasoseptal flap.

METHODS

One formalin-fixed and 9 fresh cadaveric silicone-injected specimens with 20 total sides were studied to measure the distance of the OFs to the anatomical landmarks and compare the OF presence in the nasal septum mucosa (NSM) and ethmoidal mucosa (EM).

RESULTS

The mean distance from the first to the last OF was 19.37 ± 2.16 mm in the NSM and 23.44 ± 5.42 mm in the EM. The NSM had a mean of 7.55 ± 1.31 OFs and the EM had 14.3 ± 1.78. Average OF lengths were measured at 6.44 ± 1.48 (range 3.75–12.40) mm in the NSM and 8.05 ± 1.76 (range 4.14–13.20) mm in the EM. The mean values of the EM measurements were compared with those of the NSM; the number of OFs, the distance between the first and last OF, the average OF length, and the number of OFs between anterior and posterior ethmoidal arteries in the NSM were significantly less (p < 0.05) than those in the EM. The distance between the first OF to the nasal bone on the NSM was greater than on the EM.

CONCLUSIONS

Compared with the EM, the OFs are significantly fewer in number and smaller in size in the NSM. The uppermost edge of the nasoseptal flap incision in the NSM might be safer to start below 12 mm from the cribriform plate for OF protection.

Free access

Microsurgical versus endovascular treatment of ethmoidal dural arteriovenous fistulas: systematic review and meta-analysis with a single-center case series

Chandler N. Berke, Anant Naik, Neil Majmundar, Sean Munier, Raphia Rahman, Ahsan Sattar, Priyank Khandelwal, and James K. Liu

OBJECTIVE

Ethmoidal dural arteriovenous fistulas (DAVFs) are often associated with cortical venous drainage (CVD) and a higher incidence of hemorrhage compared with DAVFs in other locations. They may be treated with open surgical disconnection or with endovascular treatment (EVT). In this systematic review and meta-analysis, the authors compare the outcomes of ethmoidal DAVFs treated with open microsurgery versus EVT and report four additional cases of ethmoidal DAVFs treated with open microsurgery in their institution.

METHODS

A literature search of the PubMed and Scopus databases was conducted between December 2021 and May 2022 to identify relevant articles published between 1990 and 2021 using the PRISMA guidelines. References were reviewed and screened by two authors independently, and disagreements were resolved through consensus. Exclusion criteria included non–English-language studies, those with an incorrect study design, those reporting DAVFs in a nonethmoidal location, and studies whose outcomes were not stratified based on DAVF location. Inclusion criteria were any studies reporting on ethmoidal DAVFs treated by either microsurgery or EVT. A risk of bias assessment was performed using the Newcastle-Ottawa Scale. The authors performed a pooled proportional meta-analysis to compare patient outcomes.

RESULTS

Twenty studies were included for analysis. Of 224 patients, 142 were treated with surgery, while 103 were treated with EVT. Seventy percent (148/210) of the patients were symptomatic at presentation, with hemorrhage being the most common presentation (48%). CVD was present in 98% of patients and venous ectasia in 61%. The rates of complete DAVF obliteration with surgery and EVT were 89% and 70%, respectively (95% CI −30% to −10%, p < 0.03). Twenty percent (21/103) of endovascularly treated fistulas required subsequent surgery. Procedure-related complications occurred in 10% of the surgical cases, compared with 13% of the EVT cases. The authors’ case series included 4 patients with ethmoidal DAVFs treated surgically with complete obliteration, without any postoperative complications.

CONCLUSIONS

The complete obliteration rates of ethmoidal DAVF appear to be higher and more definitive with microsurgical intervention than with EVT. While complication rates between the two procedures seem similar, patients treated with EVT may require further interventions for definitive treatment. The limitations of this study include its retrospective nature, the quality of studies included, and the continued evolving technologies of EVT. Future studies should focus on the association between venous drainage pattern and the proclivity toward venous ectasia or rate of hemorrhage at presentation.

Free access

Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training

Evgenii Belykh, Irakliy Abramov, Liudmila Bardonova, Ruchi Patel, Sarah McBryan, Lara Enriquez Bouza, Neil Majmundar, Xiaochun Zhao, Vadim A. Byvaltsev, Stephen A. Johnson, Amit Singla, Gaurav Gupta, Hai Sun, James K. Liu, Anil Nanda, Mark C. Preul, and Michael T. Lawton

OBJECTIVE

Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity.

METHODS

Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)–middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)–PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery–anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey.

RESULTS

A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models.

CONCLUSIONS

The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

Free access

Patient frailty association with cerebral arteriovenous malformation microsurgical outcomes and development of custom risk stratification score: an analysis of 16,721 nationwide admissions

Oliver Y. Tang, Ankush I. Bajaj, Kevin Zhao, and James K. Liu

OBJECTIVE

Patient frailty is associated with poorer perioperative outcomes for several neurosurgical procedures. However, comparative accuracy between different frailty metrics for cerebral arteriovenous malformation (AVM) outcomes is poorly understood and existing frailty metrics studied in the literature are constrained by poor specificity to neurosurgery. This aim of this paper was to compare the predictive ability of 3 frailty scores for AVM microsurgical admissions and generate a custom risk stratification score.

METHODS

All adult AVM microsurgical admissions in the National (Nationwide) Inpatient Sample (2002–2017) were identified. Three frailty measures were analyzed: 5-factor modified frailty index (mFI-5; range 0–5), 11-factor modified frailty index (mFI-11; range 0–11), and Charlson Comorbidity Index (CCI) (range 0–29). Receiver operating characteristic curves were used to compare accuracy between metrics. The analyzed endpoints included in-hospital mortality, routine discharge, complications, length of stay (LOS), and hospitalization costs. Survey-weighted multivariate regression assessed frailty-outcome associations, adjusting for 13 confounders, including patient demographics, hospital characteristics, rupture status, hydrocephalus, epilepsy, and treatment modality. Subsequently, k-fold cross-validation and Akaike information criterion–based model selection were used to generate a custom 5-variable risk stratification score called the AVM-5. This score was validated in the main study population and a pseudoprospective cohort (2018–2019).

RESULTS

The authors analyzed 16,271 total AVM microsurgical admissions nationwide, with 21.0% being ruptured. The mFI-5, mFI-11, and CCI were all predictive of lower rates of routine discharge disposition, increased perioperative complications, and longer LOS (all p < 0.001). Their AVM-5 risk stratification score was calculated from 5 variables: age, hydrocephalus, paralysis, diabetes, and hypertension. The AVM-5 was predictive of decreased rates of routine hospital discharge (OR 0.26, p < 0.001) and increased perioperative complications (OR 2.42, p < 0.001), postoperative LOS (+49%, p < 0.001), total LOS (+47%, p < 0.001), and hospitalization costs (+22%, p < 0.001). This score outperformed age, mFI-5, mFI-11, and CCI for both ruptured and unruptured AVMs (area under the curve [AUC] 0.78, all p < 0.001). In a pseudoprospective cohort of 2005 admissions from 2018 to 2019, the AVM-5 remained significantly associated with all outcomes except for mortality and exhibited higher accuracy than all 3 earlier scores (AUC 0.79, all p < 0.001).

CONCLUSIONS

Patient frailty is predictive of poorer disposition and elevated complications, LOS, and costs for AVM microsurgical admissions. The authors’ custom AVM-5 risk score outperformed age, mFI-5, mFI-11, and CCI while using threefold less variables than the CCI. This score may complement existing AVM grading scales for optimization of surgical candidates and identification of patients at risk of postoperative medical and surgical morbidity.

Open access

Endoscopic-assisted combined transcrusal anterior petrosal approach for resection of large petroclival meningioma: operative video and nuances of technique

Ali Tayebi Meybodi and James K. Liu

In this illustrative video, the authors demonstrate an endoscopic-assisted combined transcrusal anterior petrosal approach for resection of a large petroclival meningioma with significant brainstem compression involving Meckel’s cave. This unique petrosal variant provides increased petroclival exposure that can potentially preserve hearing by combining a transcrusal labyrinthectomy with anterior petrosectomy (Kawase’s approach). The advantages include multidirectional angles of attack to the brainstem and petroclival region without cerebellar retraction. Endoscopic assistance allows expanded visualization into deep surgical corridors. The surgery was performed in a two-stage fashion, and a near-total resection was achieved with cranial nerve and hearing preservation. The operative nuances are demonstrated.

The video can be found here: https://stream.cadmore.media/r10.3171/2022.1.FOCVID21257

Open access

Retrosigmoid approach for giant cystic vestibular schwannoma: subperineural dissection technique for facial nerve preservation

Ali Tayebi Meybodi, Robert W. Jyung, and James K. Liu

In this illustrative video, the authors demonstrate retrosigmoid resection of a giant cystic vestibular schwannoma using the subperineural dissection technique to preserve facial nerve function. This thin layer of perineurium arising from the vestibular nerves is used as a protective buffer to shield the facial and cochlear nerves from direct microdissection trauma. A near-total resection was achieved, and the patient had an immediate postoperative House-Brackmann grade I facial nerve function. The operative nuances and pearls of technique for safe cranial nerve and brainstem dissection, as well as the intraoperative decision and technique to leave the least amount of residual adherent tumor, are demonstrated.

The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID21128

Open access

Retractorless interforniceal approach for microsurgical resection of a papillary tumor of the pineal region: operative video and technical nuances

James K. Liu and Neil Majmundar

In this illustrative video, the authors demonstrate microsurgical resection of a papillary tumor of the pineal region using a retractorless interforniceal approach via the anterior interhemispheric transcallosal route. The tumor presented to the posterior third ventricle occluding the cerebral aqueduct, resulting in obstructive hydrocephalus. The retractorless interforniceal approach is performed in the lateral position with BICOL collagen spacers to keep the corridor open. Gross-total resection was achieved, and the patient was neurologically intact without needing a permanent shunt. The operative nuances and pearls of technique for safe microdissection and gentle handling of the retractorless interforniceal approach are demonstrated.

The video can be found here: https://stream.cadmore.media/r10.3171/2021.4.FOCVID2139.

Open access

Endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach for microsurgical resection of vermian arteriovenous malformation: operative video and technical nuances

Kevin Zhao, Joseph Quillin, and James K. Liu

In this illustrative video, the authors demonstrate resection of a superior vermian arteriovenous malformation (AVM) using the endoscopic-assisted parieto-occipital interhemispheric precuneal transtentorial approach. Lateral positioning allows for gravity-assisted access to the interhemispheric fissure without retractors. The parieto-occipital trajectory is useful in patients who have a steep tentorial angle and avoids manipulation of the occipital lobe and visual cortex. In addition, the authors utilize an angled endoscope, which allows full inspection of the resection bed after AVM removal to visualize areas hidden from the microsurgical view to minimize the chance of residual disease in a deep corridor with multiple visual obstructions.

The video can be found here: https://youtu.be/hk9nIIdtqbI

Open access

Teflon bridge technique for endoscopic-assisted microvascular decompression of ectatic basilar artery and anterior inferior cerebellar artery for trigeminal neuralgia: operative video and technical nuances

James K. Liu and Asif Shafiq

In this illustrative operative video, the authors demonstrate a Teflon bridge technique to achieve safe transposition of a large, tortuous ectatic basilar artery (BA) and anterior inferior cerebellar artery (AICA) complex to decompress the root entry zone (REZ) of the trigeminal nerve in a 61-year-old woman with refractory trigeminal neuralgia via an endoscopic-assisted retractorless microvascular decompression. Postoperatively, the patient experienced immediate facial pain relief without requiring further medications. The Teflon bridge technique can be a safe alternative to sling techniques when working in narrow surgical corridors between delicate nerves and vessels. The operative technique and surgical nuances are demonstrated.

The video can be found here: https://youtu.be/hIHX7EvZc1c