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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

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

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

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

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

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

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

Open access

James K. Liu, Kevin Zhao, Alejandro Vazquez, and Jean Anderson Eloy

Tumors of the infratemporal fossa (ITF) are surgically formidable lesions due to their deep location and proximity to critical neurovascular structures. Selecting the optimal surgical corridor for a giant ITF lesion with extensive medial and lateral extension can be challenging due to the limited surgical freedom offered by each individual approach. In this operative video, we demonstrate a case of a 44-year-old female with a giant ITF schwannoma with intracranial extension and erosion of the central skull base. Although we considered several surgical approaches, including a standard binostril endoscopic endonasal approach and an endoscopic Denker’s approach, we eventually chose a combined endoscopic endonasal and sublabial (Caldwell-Luc) transmaxillary approach. This combined approach provides significantly greater surgical freedom than a pure endonasal route to the lateral ITF. The sublabial Caldwell-Luc corridor provides a more direct “head-on” trajectory to the target of the lateral ITF than the pure endonasal route. This combined approach provides a multiportal, multicorridor access, allowing for more surgical freedom and preservation of the piriform aperture and nasolacrimal duct. This case illustrates the versatility of the combined endoscopic endonasal and sublabial transmaxillary approach for giant ITF tumors with significant lateral extension. The technical nuances and surgical concepts are demonstrated in this operative video manuscript.

The video can be found here: https://youtu.be/gy-pkjLdDgE.

Open access

James K. Liu, Kevin Zhao, and Jean Anderson Eloy

Craniopharyngioma is a rare and benign intracranial tumor of the sellar and suprasellar region. Historically, these tumors were mostly accessed through transcranial corridors and resected with microsurgical techniques. Endoscopic endonasal surgery has recently gained popularity in the treatment of these tumors and has shown at least comparable results to transcranial approaches. The endoscopic endonasal approach provides direct midline access through a transplanum transtuberculum corridor and gives excellent visualization of the undersurface of the optic chiasm to allow safe bimanual sharp dissection of the tumor from the hypothalamus. In this operative video, we demonstrate the case of a 56-year-old female who had a complex craniopharyngioma with solid and cystic components extending superolaterally into the right frontal lobe. This lesion was invasive and partially encased the right optic nerve, optic chiasm, and anterior communicating artery complex. Although a traditional transcranial approach could have been utilized, we elected for an endoscopic endonasal approach for a maximal safe near-total resection, preserving the neurovascular structures. The patient underwent radiation therapy with favorable regression of the residual tumor on subsequent imaging studies. This case illustrates the feasibility of a combined strategy of maximal safe endoscopic endonasal resection followed by early radiation therapy for a complex, invasive cystic and solid craniopharyngioma. The technical nuances of safe bimanual microsurgical dissection of tumor adhesions off of critical neurovascular structures are demonstrated.

The video can be found here: https://youtu.be/z0AINLpRZGs.

Free access

Neil Majmundar, Pratit Patel, Vincent Dodson, Ivo Bach, James K. Liu, Luke Tomycz, and Priyank Khandelwal

OBJECTIVE

The transradial approach (TRA) has been widely adopted by interventional cardiologists but is only now being accepted by neurointerventionalists. The benefits of the TRA over the traditional transfemoral approach (TFA) include reduced risk of adverse clinical events and faster recovery. The authors assessed the safety and feasibility of the TRA for neurointerventional cases in the pediatric population.

METHODS

Pediatric patients undergoing cerebrovascular interventions since implementation of the TRA at the authors’ institution were retrospectively reviewed. Pertinent patient information, procedure indications, vessels catheterized, fluoroscopy time, and complications were reviewed.

RESULTS

There were 4 patients in this case series, and their ages ranged from 13 to 15 years. Each patient tolerated the procedure performed using the TRA without any postprocedural issues, and only 1 patient experienced radial artery spasm, which resolved with the administration of intraarterial verapamil. None of the patients required conversion to the TFA.

CONCLUSIONS

The TRA can be considered a safe alternative to the TFA for neurointerventional procedures in the pediatric population and provides potential advantages. However, as pediatric patients require special consideration due to their smaller-caliber arteries, routine use of ultrasound guidance is advised when attempting the TRA.