Minimal access to deep intracranial lesions using a serial dilatation technique: Case-series and review of brain tubular retractor systems

Minimally invasive resection of intracranial lesions using tubular retractors: A single surgeon series

OBJECTIVE

Tubular retractors are increasingly used due to their low complication rates, providing easier access to lesions while minimizing trauma from brain retraction. Our study presents the most extensive series of cases performed by a single surgeon aiming to assess the effectiveness and safety of a transcortical-transtubular approach for removing intracranial lesions.

METHODS

We performed a retrospective review of patients who underwent resection of an intracranial lesion with the use of tubular retractors. Electronic medical records were reviewed for patient demographics, preoperative clinical deficits, diagnosis, preoperative and postoperative magnetic resonance imaging (MRI) scans, lesion characteristics including location, volume, extent of resection (EOR), postoperative complications, and postoperative deficits.

RESULTS

112 transtubular resections for intracranial lesions were performed. Patients presented with a diverse number of pathologies including metastasis (31.3 %), GBM (21.4 %), and colloid cysts (19.6 %) The mean pre-op lesion volume was 14.45 cm3. A gross total resection was achieved in 81 (71.7 %) cases. Seventeen (15.2 %) patients experienced early complications which included confusion, short-term memory difficulties, seizures, meningitis and motor and visual deficits. Four (3.6 %) patients had permanent complications, including one with aphasia and difficulty finding words, another with memory loss, a third with left-sided weakness, and one patient who developed new-onset long-term seizures. Mean post-operative hospitalization length was 3.8 days.

CONCLUSION

Tubular retractors provide a minimally invasive approach for the extraction of intracranial lesions. They serve as an efficient tool in neurosurgery, facilitating the safe resection of deep-seated lesions with minimal complications.

Cylinder tumor surgery in pediatric low-grade gliomas

BACKGROUND

Periventricular pediatric low-grade gliomas (pLGG) present a surgical challenge due to their deep-seated location, accessibility, and relationship with the subcortical network connections. Minimally invasive parafascicular approaches with tubular brain retractors (port brain surgery) have emerged, in recent years, as an alternative to conventional microsurgical and endoscopic approaches for removal of periventricular tumors.

OBJECTIVES

To describe the minimally invasive approach with tubular brain retractors for periventricular pLGG, its technique, applications, safety, and efficacy.

METHODS

In this article, we describe the port brain surgery techniques for periventricular pLGG as performed in different centers, with different commercialized tubular retractor systems. Illustrative cases followed by a literature review are analyzed, with a detailed description of different approaches or techniques, comparing their advantages and disadvantages with contemporary microsurgical and endoscopic approaches.

CONCLUSIONS

The port brain surgery with micro-exoscopic vision and endoscopic assistance, for the treatment of deep-seated lesions such as periventricular pLGG, is an alternative for achieving a functionally safe-gross total or subtotal-tumor resection, obtaining adequate tissue for pathological examination. This technique could offer a new dimension for a less-invasive, safe, and effective access to deep-seated tumors, offering the possibility to lower morbidity in experienced hands.

Endoport-Guided Endoscopic Excision of Intraaxial Brain Tumors

OBJECTIVE

Transcortical approaches using a spatula-based retraction system have traditionally been used for the microsurgical resection of deep-seated intraventricular and parenchymal brain tumors. Recently, transparent cylindrical or tubular retractors have been developed to provide a stable corridor to access deeper brain lesions and perform bimanual microsurgical resection. The flexible endoports minimize brain retraction injury during surgery and, along with the superior vision of endoscopes, offer several advantages over standard microsurgery. In this chapter, we describe the surgical technique of the endoport-guided endoscopic excision of deep-seated intraaxial brain tumors.

METHODS

The endoscopic endoport technique that we use at our institution for the surgical management of intraventricular and intraparenchymal brain tumors has been described in detail with illustrative cases.

RESULTS

Results from the literature review of intraventricular and intraparenchymal port surgery were analyzed, and the feasibility and safety of this technique were discussed. Surgical complication avoidance and management were highlighted. The port technique offers numerous potential advantages, including (1) reducing focal brain injury by distributing retraction forces homogenously, (2) minimizing white matter disruption and the risk of fascicle injury during cannulation, (3) ensuring the stability of the surgical corridor during the procedure, (4) preventing inadvertent expansion of the corticectomy and white fiber tract dissection throughout surgery, and (5) protecting the surrounding tissues against iatrogenic injuries caused by instrument entry and reentry.

CONCLUSION

The endoport-assisted endoscopic technique is safe and offers an effective alternative option for the resection of intraventricular and intraparenchymal lesions.

Impact of Preoperative Mapping and Intraoperative Neuromonitoring in Minimally Invasive Parafascicular Surgery for Deep-Seated Lesions

BACKGROUND

Transsulcal tubular retractor-assisted minimally invasive parafascicular surgery changes the surgical strategy for deep-seated lesions by promoting a deficit-sparing approach. When integrated with preoperative brain mapping and intraoperative neuromonitoring (IONM), this approach may potentially improve patient outcomes. In this study, we assessed the impact of preoperative brain mapping and IONM in tubular retractor-assisted neuro-oncological surgery.

METHODS

This retrospective single-center cohort study included patients who underwent transsulcal tubular retractor-assisted minimally invasive parafascicular surgery for resection of deep-seated brain tumors from 2016 to 2022. The cohort was divided into 3 groups: group 1, no preoperative mapping or IONM (17 patients); group 2, IONM only (25 patients); group 3, both preoperative mapping and IONM (38 patients).

RESULTS

We analyzed 80 patients (33 males and 47 females) with a median age of 46.5 years (range: 1-81 years). There was no significant difference in mean tumor volume (26.2 cm3 [range 1.07-97.4 cm3]; P = 0.740) and mean preoperative depth of the tumor (31 mm [range 3-65 mm], P = 0.449) between the groups. A higher proportion of high-grade gliomas and metastases was present within group 3 (P = 0.003). IONM was related to fewer motor (P = 0.041) and language (P = 0.032) deficits at hospital discharge. Preoperative mapping and IONM were also related to shorter length of stay (P = 0.008).

CONCLUSIONS

Preoperative and intraoperative brain mapping and monitoring enhance transsulcal tubular retractor-assisted minimally invasive parafascicular surgery in neuro-oncology. Patients had a reduced length of stay and prolonged overall survival. IONM alone reduces postoperative neurological deficit.

Efficacy and safety of the endoscopic "wet-field" technique for removal of supratentorial cavernous malformations

OBJECTIVE

Cerebral cavernous malformations (CMs) presenting with focal neurological symptoms or mass effects require surgical removal. In recent years, cylindrical retractors have been widely utilized for the removal of deep-seated lesions during both microscopic and endoscopic surgery. In the present study, we evaluated the efficacy and safety of endoscopic transcylinder removal of CMs using a novel wet-field technique.

METHODS

We included 13 patients with supratentorial CMs who had undergone endoscopic transcylinder surgery between April 2013 and March 2022. One patient experienced recurrence of the CM and underwent a second endoscopic transcylinder surgery. Therefore, we retrospectively evaluated 14 procedures. The surgical field was continuously irrigated with artificial cerebrospinal fluid to maintain expansion and visualization of the tumor bed. We termed this method as the "wet-field technique." Patient characteristics, symptoms, and pre- and postoperative magnetic resonance imaging results were obtained from medical records.

RESULTS

The average maximum CM diameter was 35.3 mm (range: 10-65 mm). Cylinder diameters were 6 mm in eight procedures, 10 mm in four procedures, and 17 mm in one procedure. Wet-field technique was applied in all cases. The endoscope provided a bright field of view even under water. Continuous water irrigation made it easier to observe the entire tumor bed which naturally expanded by water pressure. Gross total resection was achieved in 13 procedures, while subtotal resection was achieved in one procedure. No surgical complications were observed.

CONCLUSIONS

The endoscopic transcylinder removal using wet-field technique is safe and effective for the removal of symptomatic intracranial supratentorial CMs.

Combined intra- and extra-endoscopic techniques for endoscopic intraventricular surgery with a new mini-tubular port

Objective

Intraoperative hemorrhage represents a major risk during endoscopic intraventricular surgery. There are very few publications describing the maintenance of hemostasis during conventional endoscopic intraventricular surgery. Here, we designed a new mini-tubular port to combine intra- and extra-endoscopic techniques for endoscopic intraventricular surgery. With this new methodology, complicated techniques can be performed more efficiently with improved bleeding control.

Methods

The new mini-tubular port consists of an outer sheath and an obturator. The sheath is a thin-walled transparent cylinder that is 0.35 mm thick, 10 mm in diameter, and 90 mm in length. In this report, we describe the use of the mini-tubular port on 36 patients receiving endoscopic intraventricular surgery.

Results

The study enrolled 36 patients, with a median age of 45 years (range: 0–72 years), of which 19 were male and 17 were female. Pure ETV (endoscopic third ventriculostomy) was performed in 20 patients and pure biopsy was performed in 2. ETV and biopsy were performed in five patients, ETV and the removal of cysticerci were performed in five, cyst fenestration was performed in one, ETV and cyst fenestration were performed in two, and ETV and shunt removal were performed in one patient. Two patients received microscopic surgery following endoscopic surgery during the same operation. A total of 17 patients (47%) underwent extra-endoscopic techniques. The median Karnofsky Performance Status (KPS) score of the patients prior to surgery was 50, while the median KPS score of the patients after one month of surgery was 80; these scores were significantly different (P < 0.05), as determined by Wilcoxon's test. In total, 27 patients had a KPS score ≥70% and 75% of patients had a favorable prognosis one month after surgery. None of the patients experienced seizure.

Conclusion

The new mini-tubular port can conveniently combine intra- and extra-endoscopic techniques for endoscopic intraventricular surgery. The application of these techniques can efficiently control bleeding during surgery, help improve the confidence of the surgeons involved, and provide a highly efficient approach for performing complicated procedures.

[Brain retraction injury]

This review is devoted to various techniques for reduction of brain damage during retraction. Searching for reports was carried out in Russian and English languages using the PubMed database (n=721) without restrictions on language, date and study design according to the following keywords: «brain retraction injury», «spatula brain retractors», «tubular brain retractors», «retractorless neurosurgery». Primary screening and exclusion of duplicate manuscripts allowed us to single out the main group of articles (n=121). Some reports were excluded due to non-compliance with inclusion criteria (no description of methods, few references and insufficient data). The final list included 32 studies which were represented by cohort studies, retrospective analyses of surgical interventions, as well as experimental and laboratory studies. Small number of publications did not allow us to obtain unambiguous conclusions. Further research is required to reduce brain retraction trauma.

Resection of intra- and paraventricular malignant brain tumors using fluorescein sodium-guided neuroendoscopic transtubular approach

BACKGROUND

The requirement of brain retraction and difficulty in distinguishing the tumor demarcation are challenging in conventional approaches to intra- and paraventricular malignant tumors (IV-PVMTs). Tubular retractors can minimize the retraction injury, and fluorescein-guided (FG) surgery may promote the resection of tumors. Our aim is to evaluate the feasibility, safety, and effectiveness of fluorescein-guided endoscopic transtubular surgery for the resection of IV-PVMTs.

METHODS

Twenty patients with IV-PVMTs underwent FG endoscopic transtubular tumor resection. Fluorescein sodium was administered before the dural opening. The intraoperative fluorescence staining was classified as "helpful" and "unhelpful" based on surgical observation. Extent of resection was assessed using postoperative magnetic resonance imaging. Karnofsky Performance Status (KPS) score was used to evaluate the general physical condition of patients.

RESULTS

There were 9 glioblastomas, 4 anaplastic astrocytomas and 7 metastatic tumors. "Helpful" fluorescence staining was observed in 16(80%) of 20 patients. Gross total resection was achieved in 16(80%) cases, near-total in 3(15%) cases, and subtotal in 1 (5%) case. No intra- or postoperative complications related to the fluorescein sodium occurred. The median preoperative KPS score was 83, and the median KPS score 3-month after surgery was 88.

CONCLUSION

FG endoscopic transtubular surgery is a feasible technique for the resection of IV-PVMTs. It may be a safe and effective option for patients with these tumors. Future prospective randomized studies with larger samples are needed to confirm these preliminary data.

Acquisition of Basic Micro-Neurosurgical Skills Using Cavitron Ultrasonic Aspirator in Low-Cost Readily Available Models: The Egg Model

BACKGROUND

Attainment of micro-neurosurgical skills is a challenge in teaching hospitals throughout training. Models that mimic the workflow as well as haptics are time-consuming, expensive, and unsuitable to serve as a routine platform. Our objective was to present a model and a set of tasks, based on a hard-boiled egg, microscope, and a Cavitron ultrasonic aspirator (CUSA; Integra Lifesciences Corp., Tullamore, Ireland), which is cheap, easy to setup and can be used for training microsurgery and CUSA skills, required for removal of deep-seated tumors.

METHODS

The goal was to remove the egg yolk from within a hard-boiled egg, representing an intrinsic brain tumor, surrounded by the egg's white, representing adjacent brain tissue, while preserving it. Assessment was based on the yolk's exposure, completeness of removal, and collateral damage and task completion duration, with repeated trials (n = 4), for validation purposes, for 6 operators with different experience levels.

RESULTS

Improvement in overall score (mean of 47.5 ± 19 in the first trial vs. 80.0 ± 12 in the fourth trial, P < 0.01), and task duration completion (mean initial duration of 21:25 ± 4:52 minutes to 15:30 ± 5:17 minutes, P < 0.01) was observed. Parameters gradually improved on repeated attempts, and experience level of the operators correlated with scores.

CONCLUSIONS

The egg model is an easy-to-handle, cheap model that enables the acquisition of basic micro-neurosurgical skills and basic workflow required for removing of intrinsic brain tumors. This study has validated and defined reproducible tasks that can be scored, correlated with performance. This model can be incorporated into a resident's routine and potentially provide an accessible training platform for neurosurgical trainees.

Minimally-invasive tubular retraction ports for intracranial neurosurgery: History and future perspectives

Brain retraction is a necessary yet potentially damaging requirement of accessing lesions located in deep structures. The development of minimally-invasive tubular retractors (MITRs) provides the theoretical advantage of maximizing visualization of and access to deep-seated lesions, all while minimizing collateral tissue damage. These advantages make MITRs preferable to traditional bladed retractors in the majority of deep-seated lesions. Several commercially-available MITR systems currently exist and have been shown to aid in achieving excellent outcomes with acceptable safety profiles. Nevertheless, important drawbacks to currently-available MITR systems exist. Continued pursuit of an ideal MITR system that provides maximal visualization and access to deep-seated lesions while minimizing retraction-related tissue damage is therefore important. In this review, we discuss the historical development of MITRs, the advantages of MITRs compared to traditional bladed retractors, and opportunities to improve the development of prospective MITRs.

Transcortical Approach to Deep-Seated Intraventricular and Intra-axial Tumors Using a Tubular Retractor System: A Technical Note and Review of the Literature

BACKGROUND

 Retraction of white matter overlying a brain lesion can be difficult without causing significant trauma especially when using traditional methods of bladed retractors. These conventional retractors can produce regions of focal pressure resulting in contusions and areas of infarct.

METHODS

 In this article, we present a retrospective case series of six patients with deep-seated intraventricular and intra-axial tumors that were approached using a ViewSite Brain Access System (tubular retractor). The authors describe a unique method of creating a pathway using a dilated glove. We shall also review the relevant literature that reports this type of surgery. Cases included three cases with third ventricular colloid cysts, one case of a third ventricular arachnoid cyst, one case with a lateral ventricular neurocytoma, and a case with a deeply seated intra-axial metastatic tumor.

RESULTS

 Gross total resection was achieved in five cases with small residual in the central neurocytoma operation, with no documented neurological deficit in any case. One case had persistent memory problems and one case had continuing decline from the metastatic disease.

CONCLUSION

 The introduction of tubular-shaped retractor systems has offered the advantage of reducing retraction pressures and distributing any remaining force in a more even and larger distributed area, thus reducing the risk of previous associated morbidity while also permitting great visualization of the target lesion.

Management of large intraventricular meningiomas with minimally invasive port technique: a three-case series

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective. To date, most of the literature regarding the tubular retractors used in brain surgery is comprised of individual case reports that describe the successful resection of deep-seated lesions such as thalamic pilocytic astrocytomas, colloid cysts in the third ventricle, hematomas, and cavernous angiomas. The authors describe their experience using a tubular retractor system with three different cases involving large intraventricular meningiomas and examine radiographic and patient outcomes. A single-institution, retrospective case series was performed from a skull base database. Patients who underwent resection of intraventricular > 4-cm meningiomas with port technology were identified. The authors reviewed three cases to illustrate the feasibility of minimal access port surgery for the resection of these lesions. Complete resection was achieved in all cases. None of the patients developed permanent neurological deficits. There were no major complications related to surgery and no mortalities. Good clinical and surgical outcomes for atrium meningiomas can be achieved through the minimally invasive port technique and tumor size does not appear to be a limitation.

Intraoperative MRI-assisted neuro-port surgery for the resection of cerebral intraparenchymal cavernous malformation

Background

Intraparenchymal cerebral cavernous malformation is difficult to localize intraoperatively with conventional frameless navigation due to the “brain shift” effect. We conducted this study to evaluate the efficacy and safety of intraoperative magnetic resonance image (iMRI)-assisted neuro-port surgery for the resection of cerebral intraparenchymal cavernous malformation.

Methods

Between April 2016 and December 2017, 54 consecutive patients with intraparenchymal cerebral cavernous malformation who get surgical treatment in our hospital were enrolled into this study. Twenty-one patients were treated using iMRI-assisted neuro-port surgery (experiment group), and 33 patients underwent treatment by conventional microsurgery (control group). The iMRI was used in all cases for the compensation of the “brain shift” effect and keeping the navigation system up-to-date. The surgical resection rate, the total operation time, and the preoperative and postoperative Karnofsky Performance Status (KPS) scores were determined to evaluate the operative procedures.

Results

There were no significant differences between the two groups in mean age, gender ratio, and volume of lesions (P > 0.05). For the experiment group, the average duration of the procedure was 188.8 min with total resection of the lesions achieved in all 21 cases. For the control group, the average duration of the procedure was 238.2 min with total resection of the lesions achieved in 25 of 33 cases. The differences in the average duration of the procedure and the number of totally resected lesions between the two groups were statistically significant (P < 0.05). Regarding postoperative neurological function, postoperative KPS scores for the experiment group were significantly higher than those of the control group (P = 0.018).

Conclusion

Our results show that iMRI-assisted neuro-port surgery is helpful for intraparenchymal cerebral cavernous malformation surgery. The method provides high accuracy and efficiency for lesion targeting and permits excellent anatomic orientation. With the assistance of iMRI technology, we achieved a higher resection rate and a lower incidence of postoperative neurological deficits. Additionally, iMRI is helpful for the compensation of the “brain shift” effect, and it can update the navigation system.

Electronic supplementary material

The online version of this article (10.1186/s41016-019-0171-x) contains supplementary material, which is available to authorized users.

Mini-Tubular Access Surgery: A Single Surgeon's 12 Years in the Corridors of the Neuroaxis

BACKGROUND

 Tubular approach surgery now includes complex spinal and cranial procedures. Aided by modified instrumentation and frameless stereotaxy, minimal access surgery is being offered for a growing array of neurosurgical conditions.

METHODS

 This article explores the flexibility and adaptability of the tubular retractor system for multiple indications by highlighting the 12-year experience of the primary surgeon using a tubular retractor system reported for the entire neuroaxis including intracranial, foramen magnum, and the craniocaudal extent of the spine for intra- and extradural pathologies. For this article we have not analyzed our experience with degenerative spinal disease. Patient characteristics, pathology, resection results, length of hospital stay, and complications are discussed.

RESULTS

 From August 2005 through March 2017, 538 patients underwent neurosurgical procedures with mini-tubular access. Of these, the 127 patients who underwent mini-tubular access operations for nontraditional indications are discussed here. There were 65 women and 61 men with an average age of 53.5 years. The cases by anatomical location are as follows: 27 cranial cases, 11 foramen magnum decompressions, and 89 for spinal indications. The cranial pathologies included primary and metastatic tumors. The spinal pathologies included intra- and extradural spinal tumors, spina bifida occulta, syringomyelia, and other cystic lesions in the spine. In the vast majority of the patients where gross total resection was the goal, it was achieved. The mean length of stay was 2.94 days.

CONCLUSIONS

 This report demonstrates that mini-tubular access surgery can be adapted to pathologies in the entire neuroaxis with outcomes that are comparable with open techniques. Limited tissue dissection, smaller incisions, and limited bone resection make the mini-tubular access approach a desirable option when feasible. Greater experience with all of these techniques is needed before the definitive status of these procedures in the neurosurgical armamentarium can be demonstrated.

Minimally Invasive Bilateral Anterior Cingulotomy via Open Minicraniotomy Using a Novel Multiport Cisternoscope: A Cadaveric Demonstration

BACKGROUND

Bilateral anterior cingulotomy has been used to treat chronic pain, obsessive compulsive disorder, and addictions. Lesioning of the target area is typically performed using bilateral stereotactic electrode placement and target ablation, which involves transparenchymal access through both hemispheres.

OBJECTIVE

To evaluate an endoscopic direct-vision lesioning using a unilateral parasagittal minicraniotomy for minimally invasive bilateral anterior cingulotomy using a novel multiport endoscope through the anterior interhemispheric fissure.

METHODS

A novel multiport magnetic resonance imaging (MRI)-compatible neuroendoscope prototype is used to demonstrate cadaveric cingulate lesioning through a lateral imaging port while simultaneously viewing the pericallosal arteries as landmarks through a tip imaging port. The lateral port enables extended lesioning of the gyrus while rotation of the endoscope about its axis provides access to homologous areas of both hemispheres.

RESULTS

Cadaver testing confirmed the capability to navigate the multiport neuroendoscope between the hemispheres using concurrent imaging from the tip and lateral ports. The lateral port enabled exploration of the gyrus, visualization of lesioning, and subsequent inspection of lesions. Tip-port imaging provided navigational cues and allowed the operator to ensure that the endoscope tip did not contact tissue. The multiport design required instrument rotation in the coronal plane of only 20° to lesion both gyri, while a standard endoscope necessitated a rotation of 54°.

CONCLUSION

Multiport MRI-compatible endoscopy can be effectively used in cisternal endoscopy, whereby a unilateral parasagittal minicraniotomy can be used for endoscopic interhemispheric bilateral anterior cingulotomy.

Minimally Invasive Surgical Outcomes for Deep-Seated Brain Lesions Treated with Different Tubular Retraction Systems: A Systematic Review and Meta-Analysis

BACKGROUND

Minimally invasive surgery using tubular retractors was developed to minimize injury of surrounding brain during the removal of deep-seated lesions. No evidence supports the superiority of any available tubular retraction system in the treatment of these lesions. We conducted a systematic review and meta-analysis to evaluate outcomes and complications after the resection of deep-seated lesions with tubular retractors and among available systems.

METHODS

A PRISMA compliant systematic review was conducted on PubMed, Embase, and Scopus to identify studies in which tubular retractors were used to resect deep-seated brain lesions in patients ≥18 years old.

RESULTS

The search strategy yielded 687 articles. Thirteen articles complying with inclusion criteria and quality assessment were included in the meta-analysis. A total of 309 patients operated on between 2008 and 2018 were evaluated. The most common lesions were gliomas (n = 127), followed by metastases (n = 101) and meningiomas (n = 19). Four different tubular retractors were used: modified retractors (n = 121, 39.1%); METRx (n = 60, 19.4%); BrainPath (n = 92, 29.7%); and ViewSite Brain Access System (n = 36,11.7%). Estimated gross total resection rate was 75% (95% confidence interval, 69%-80%; I² = 9%), whereas the estimated complication rate was 9% (95% confidence interval: 6%-14%; I² = 0%). None of the different brain retraction systems was found to be superior regarding extent of resection or complications on multiple comparisons (P > 0.05).

CONCLUSIONS

Tubular retractors represent a promising tool to achieve maximum safe resection of deep-seated brain lesions. However, there does not seem to be a statistically significant difference in extent of resection or complication rates among tubular retraction systems.

Minimally invasive trans-sulcal parafascicular surgical resection of cerebral tumors: translating anatomy to early clinical experience

The minimally invasive port-based trans-sulcal parafascicular surgical corridor (TPSC) has incrementally evolved to provide a safe, feasible, and effective alternative to access subcortical and intraventricular pathologies. A detailed anatomical foundation is important in mitigating cortical and white matter tract injury with this corridor. Thus, the aims of this study are (1) to provide a detailed anatomical construct and overview of TPSCs and (2) to translate an anatomical framework to early clinical experience. Based on regional anatomical constraints, suitable parafascicular entry points were identified and described. Fiber tracts at both minimal and increased risks for each corridor were analyzed. TPSC-managed cases for metastatic or primary brain tumors were retrospectively reviewed. Adult patients 18 years or older with Karnofsky Performance Status (KPS) ≥ 70 were included. Subcortical brain metastases between 2 and 6 cm or primary brain tumors between 2 and 5 cm were included. Patient-specific corridors and trajectories were determined using MRI-tractography. Anatomy: The following TPSCs were described and translated to clinical practice: superior frontal, inferior frontal, inferior temporal, intraparietal, and postcentral sulci. Clinical: Eleven patients (5 males, 6 females) were included (mean age = 52 years). Seven tumors were metastatic, and 4 were primary. Gross total, near total, and subtotal resection was achieved in 7, 3, and 1 patient(s), respectively. Three patients developed intraoperative complications; all recovered from their intraoperative deficits and returned to baseline in 30 days. A detailed TPSC anatomical framework is critical in conducting safe and effective port-based surgical access. This review may represent one of the few early translational TPSC studies bridging anatomical data to clinical subcortical and intraventricular surgical practice.

Evaluation of multi-wavelengths LED-based photoacoustic imaging for maximum safe resection of glioma: a proof of concept study

PURPOSE

A real-time intra-operative imaging modality is required to update the navigation systems during neurosurgery, since precise localization and safe maximal resection of gliomas are of utmost clinical importance. Different intra-operative imaging modalities have been proposed to delineate the resection borders, each with advantages and disadvantages. This preliminary study was designed to simulate the photoacoustic imaging (PAI) to illustrate the brain tumor margin vessels for safe maximal resection of glioma.

METHODS

In this study, light emitting diode (LED)-based PAI was selected because of its lower cost, compact size and ease of use. We developed a simulation framework based on multi-wavelength LED-based PAI to further facilitate PAI during neurosurgery. This framework considers a multilayer model of the tumoral and normal brain tissue. The simulation of the optical fluence and absorption map in tissue at different depths was computed by Monte Carlo. Then, the propagation of initial photoacoustic pressure was simulated by using k-wave toolbox.

RESULTS

To evaluate the LED-based PAI, we used three evaluation criteria: signal-to-noise ratio (SNR), contrast ratio (CR) and full width of half maximum (FWHM). Results showed that by using proper wavelengths, the vessels were recovered with the same axial and lateral FWHM. Furthermore, by increasing the wavelength from 532 to 1064 nm, SNR and CR were increased in the deep region. The results showed that vessels with larger diameters at same wavelength have a higher CR with average improvement 28%.

CONCLUSION

Multi-wavelength LED-based PAI provides detailed images of the blood vessels which are crucial for detection of the residual glioma: The longer wavelengths like 1064 nm can be used for the deeper tumor margins, and the shorter wavelengths like 532 nm for tumor margins closer to the surface. LED-based PAI may be considered as a promising intra-operative imaging modality to delineate tumor margins.

[microsurgery 'burr hole' for intracranial tumors and mesial temporal lobe epilepsy]

PURPOSE

In recent years, neurosurgery has been characterized by a clear tendency towards the development of minimally invasive and less traumatic surgical approaches. To minimize the degree of injury to the brain tissue, we have proposed burr hole-based microsurgical approaches.

MATERIAL AND METHODS

In the period between February 2016 and February 2019, more than 500 microsurgical interventions were performed through a 14 mm burr hole using a technique that we called burr-hole microneurosurgery; to date, 200 of these have been analyzed. The age of patients varied from 16 to 79 years (median, 38 years). Female patients predominated - 1.6:1. Surgery for intracranial lesions with various locations was performed in 176 cases; in the remaining 24 cases, patients with hippocampal sclerosis underwent selective amygdalohippocampectomy.

RESULTS

Various surgical approaches were used: transcortical approach in 81 (40.5%) cases; retro-sigmoid approach in 38 (19%); sub-temporal approach in 32 (16%); infratentorial supracerebellar approach in 25 (12.5%); interhemispheric approach in 17 (8.5%); telovelar approach in 5 (2.5%); trans-eyebrow approach in 2 cases. The resection degree was evaluated in 167 patients with planned maximum tumor resection. Resection was total and almost total in 145 (87%) patients, subtotal in 15 (9%), and partial in 7 (4%). The surgery duration varied from 35 to 300 min (mean, 80 min). The extubation time after surgery ranged from 5 min to 5 days (mean, 70 min). In 195 (97.5%) cases, patients were verticalized within the first 3 days after surgery.

CONCLUSION

The proposed burr hole technique enables successful surgery in patients with various intracranial pathologies, using a smaller trepanation window compared to that in keyhole surgery. The proposed burr hole technique minimizes injury to the brain substance, significantly reduces patient's exposure to anesthesia, and decreases the entire duration of surgery.

Utility of Tubular Retractors Augmented with Intraoperative Ultrasound in the Resection of Deep-seated Brain Lesions: Technical Note

Traditional brain retraction has been associated with significant damage to the healthy brain tissue particularly when attempting to expose a deep-seated lesion of the brain. Tubular retractors tend to provide a surgical corridor to treat these lesions while minimizing the extent of retraction on the brain. Intraoperative ultrasound can be used as a handy adjunct in maximizing the safe resection primarily by identifying the entry point, visualizing the lesion, and providing real-time feedback on the extent of resection. The authors provide a technical note with case illustrations on the use of tubular retractors augmented with intraoperative ultrasound to ensure a maximal safe resection of deep-seated brain lesions.

Tubular brain tumor biopsy improves diagnostic yield for subcortical lesions

PURPOSE

Molecular data has become an essential part of the updated World Health Organization (WHO) grading of central nervous system tumors. However, stereotactic needle biopsies provide only small volume specimens and limit the extent of histologic and molecular testing that can be performed. We assessed the use of a tubular retractor-based minimally invasive biopsy technique to provide improved tissue yield and diagnostic data compared to needle biopsy.

METHODS

Eighteen patients underwent an open transtubular biopsy compared to 146 stereotactic biopsies during the years of 2010-2018.

RESULTS

Tubular biopsies resulted in a higher volume of tissue provided to the pathologist than needle biopsies (1.26 cm³ vs. 0.3 cm³; p < 0.0001). There was a higher rate of non-diagnostic sample with stereotactic compared to transtubular biopsy (13% vs. 0%; p = 0.13). Six patients who underwent stereotactic biopsy required reoperation for diagnosis, while no transtubular biopsy patient required reoperation in order to obtain a diagnostic specimen. Postoperative hematoma was the most common post-operative complication in both groups.

CONCLUSIONS

Stereotactic transtubular biopsies are a viable alternative to stereotactic needle biopsies with excellent rates of diagnostic success and acceptable morbidity relative to the needle biopsy technique. As molecular data begins to increasingly drive treatment decisions, additional biopsy techniques that afford large tissue volumes may be necessary to adapt to the new needs of pathologists and treating oncologists.

Use of Tubular Retractor for Resection of Colloid Cysts: Single Surgeon Experience and Review of the Literature

BACKGROUND

Colloid cysts are challenging lesions to access. Various surgical approaches are utilized which all require brain retraction, creating focal pressure, local trauma, and potentially surgical morbidity. Recently, tubular retractors have been developed that reduce retraction pressure by distributing it radially. Such retractors may be beneficial in colloid cyst resection.

OBJECTIVE

To retrospectively review a single neurosurgeon's case series, as well as the literature, to determine the efficacy and safety profile of transtubular colloid cyst resections. We also aim to describe our operative technique for this approach.

METHODS

We conducted a retrospective review of colloid cyst resections using either ViewSite Brain Access System (Vycor Medical, Boca Raton, Florida) or BrainPath (NICO, Indianapolis, Indiana) tubular retractors performed by a single neurosurgeon from 2015 to 2017 (n = 10). A literature review was performed to find all published cases of transtubular colloid cyst resections.

RESULTS

Gross total resection was achieved in all patients. Early neurologic deficit rate was 10% (n = 1), and permanent neurologic deficit rate was 0%. There were no postoperative seizures or venous injuries. Average hospital stay was 2.0 d. There was no evidence of recurrence at average follow-up length of 13.6 mo. A literature review demonstrated nine studies (n = 77) with an overall complication rate of 7.8%.

CONCLUSION

Tubular retractors offer an attractive surgical corridor for colloid cyst resections, avoiding much of the morbidity of interhemispheric approaches, while minimizing damage to normal cortex. There were no permanent complications in our series of ten cases, and a literature review found a similarly benign safety profile.

Infradentate Approach to the Fourth Ventricle

BACKGROUND

The use of minimally invasive transcranial ports for the resection of deep-seated lesions has been shown to be safe and effective for supratentorial lesions. The routine use of this surgical modality for posterior fossa masses has not been well established in the literature. In particular, fourth ventricular tumors are not the typical target for neuro-port surgery because of potential injury to the dentate nucleus.

OBJECTIVE

To describe the use of a tubular retractor system to reach the fourth ventricle while sparing the cerebellar vermis and the dentate nucleus. Three cases illustrations are presented.

METHODS

Surgical access to the fourth ventricle was developed sparing the cerebellar vermis and the dentate nucleus. The authors reviewed 3 cases to illustrate the feasibility of minimal access transcerebellar port surgery for the resection of these lesions using an infradentate access.

RESULTS

None of the patients developed new neurological deficits and the pathology was successfully resected in all cases. There were no major complications related to surgery and no mortalities.

CONCLUSION

The infradentate approach obviates the need for traditional approaches to the fourth ventricle, thus making this challenging target in the posterior fossa more accessible to neurosurgeons. The authors observed successful removal of lesions involving the fourth ventricle while avoiding any associated morbidity or mortality.

Transtubular excisional biopsy as a rescue for a non-diagnostic stereotactic needle biopsy-case report and literature review

Stereotactic needle biopsy, a standard of care for acquiring deep-seated pathology, has limitations and risks in some situations. We present an uncommon case with basal ganglia dematiaceous mycetoma. Due to the firm consistency of the lesion, the initial stereotactic needle biopsy failed to provide a diagnosis. In a second operation, transtubular excisional biopsy was successfully performed to remove the entire mycetoma. We reviewed recent case series of transtubular approaches to deep-seated brain lesions and suggest this method could be a rescue for a non-diagnostic stereotactic needle biopsy and even may be the approach of choice in some cases.

BrainPath-Mediated Resection of a Ruptured Subcortical Arteriovenous Malformation

BACKGROUND

Although tubular retractor systems have gained popularity for other indications, there have been few reports of their use for arteriovenous malformation (AVM) surgery. A patient was diagnosed with a ruptured 1.2-cm subcortical AVM after presenting with intracerebral hemorrhage in the right frontal lobe and anterior basal ganglia. The characteristics of this AVM made it amenable to resection using a tubular retractor.

OBJECTIVE

To demonstrate the feasibility and safety of AVM resection using a tubular retractor system.

METHODS

Resection of the ruptured 1.2-cm subcortical AVM was performed utilizing the BrainPathTM (NICO corp, Indianapolis, Indiana) tubular retractor system.

RESULTS

The BrainPathTM approach provided sufficient visualization and surgical freedom to permit successful AVM resection and hematoma evacuation. Postoperative imaging demonstrated near total hematoma removal and angiographic obliteration of the AVM. There were no complications, and the patient made an excellent recovery.

CONCLUSION

Tubular retractors warrant consideration for accessing small, deep, ruptured AVMs. The nuances of such systems and their role in AVM surgery are discussed.

Laser interstitial thermal therapy followed by minimal-access transsulcal resection for the treatment of large and difficult to access brain tumors

OBJECTIVE

Laser interstitial thermal therapy (LITT), sometimes referred to as “stereotactic laser ablation,” has demonstrated utility in a subset of high-risk surgical patients with difficult to access (DTA) intracranial neoplasms. However, the treatment of tumors larger than 10 cm3 is associated with suboptimal outcomes and morbidity. This may limit the utility of LITT in dealing with precisely those large or deep tumors that are most difficult to treat with conventional approaches. Recently, several groups have reported on minimally invasive transsulcal approaches utilizing tubular retracting systems. However, these approaches have been primarily used for intraventricular or paraventricular lesions, and subtotal resections have been reported for intraparenchymal lesions. Here, the authors describe a combined approach of LITT followed by minimally invasive transsulcal resection for large and DTA tumors.

METHODS

The authors retrospectively reviewed the results of LITT immediately followed by minimally invasive, transsulcal, transportal resection in 10 consecutive patients with unilateral, DTA malignant tumors > 10 cm3. The patients, 5 males and 5 females, had a median age of 65 years. Eight patients had glioblastoma multiforme (GBM), 1 had a previously treated GBM with radiation necrosis, and 1 had a melanoma brain metastasis. The median tumor volume treated was 38.0 cm3.

RESULTS

The median tumor volume treated to the yellow thermal dose threshold (TDT) line was 83% (range 76%–92%), the median tumor volume treated to the blue TDT line was 73% (range 60%–87%), and the median extent of resection was 93% (range 84%–100%). Two patients suffered mild postoperative neurological deficits, one transiently. Four patients have died since this analysis and 6 remain alive. Median progression-free survival was 280 days, and median overall survival was 482 days.

CONCLUSIONS

Laser interstitial thermal therapy followed by minimally invasive transsulcal resection, reported here for the first time, is a novel option for patients with large, DTA, malignant brain neoplasms. There were no unexpected neurological complications in this series, and operative characteristics improved as surgeon experience increased. Further studies are needed to elucidate any differences in survival or quality of life metrics.

Dual-Channel Minimally Invasive Endoscopic Port for Evacuation of Deep-Seated Spontaneous Intracerebral Hemorrhage with Obstructive Hydrocephalus

BACKGROUND

In minimally invasive endoscopic port surgery, the medium is air, and the image is clearer than in fluid. The most commonly used port is a single-channel port, which accommodates the rod lens of the endoscope and 2 microsurgical instruments. This setup decreases the freedom of movement of the 3 instruments, making the bimanual procedure difficult. We describe a novel "dual-channel" endoscopic port to facilitate a bimanual refinement procedure for removing deep-seated spontaneous intracerebral hematomas, and we demonstrate the feasibility of this method.

METHODS

The small channel accommodates a 0° endoscope lens, and the large channel accommodates 2 microsurgical instruments. This method was used in 8 patients with deep-seated spontaneous intracerebral hematomas with obstructive hydrocephalus. It was necessary to evacuate the deep-seated hematomas in these patients as soon as possible to recover the circulation of cerebrospinal fluid.

RESULTS

Dual-channel port surgery was performed in 8 patients with an average age of 55 years (range, 44-79 years). The time from ictus to surgery ranged from 4 hours to 12 days. The duration of drainage tube placement was 2-5 days. The hematomas in all patients, in the third ventricle or thalamus, were evacuated thoroughly. In each patient, improvements in Glasgow Coma Scale scores were observed from admission to discharge.

CONCLUSIONS

The dual-channel endoscopic port facilitated bimanual refinement microsurgery during the evacuation of deep-seated intracerebral hematomas, and it prevented the disturbance of the 3 instruments without restraining the scope of the operation during the microsurgical procedure.

Endoport-Assisted Microsurgical Treatment of a Ruptured Periventricular Aneurysm

Background and Importance. Ruptured periventricular aneurysms in patients with moyamoya disease represent challenging pathologies. The most common methods of treatment include endovascular embolization and microsurgical clipping. However, rare cases arise in which the location and anatomy of the aneurysm make these treatment modalities particularly challenging. Clinical Presentation. We report a case of a 34-year-old female with moyamoya disease who presented with intraventricular hemorrhage. CT angiography and digital subtraction angiography revealed an aneurysm located in the wall of the atrium of the right lateral ventricle. Distal endovascular access was not possible, and embolization risked the sacrifice of arteries supplying critical brain parenchyma. Using the BrainPath endoport system, the aneurysm was able to be accessed. Since the fusiform architecture of the aneurysm prevented clip placement, the aneurysm was ligated with electrocautery. Conclusion. We demonstrate the feasibility of endoport-assisted approach for minimally invasive access and treatment of uncommon, distally located aneurysms.

Utility of tubular retractors to minimize surgical brain injury in the removal of deep intraparenchymal lesions: a quantitative analysis of FLAIR hyperintensity and apparent diffusion coefficient maps

OBJECT

Brain retraction systems are frequently required to achieve surgical exposure of deep-seated brain lesions. Spatula-based systems can be associated with injury to the cortex and deep white matter, particularly adjacent to the sharp edges, which can result in uneven pressure on the parenchyma over the course of a long operation. The use of tubular retractor systems has been proposed as a method to overcome these limitations. There have been no studies assessing the degree of brain injury associated with the use of tubular retractors.

METHODS

Twenty patients were retrospectively identified at Weill Cornell Medical College who underwent resection of deep-seated brain lesions between 2005 and 2014 with the aid of a METRx tubular retractor system. Using the Brainlab software, pre- and postoperative images were analyzed to assess volume, depth, extent of resection, and change in postoperative MR FLAIR hyperintensity and restricted diffusion on diffusion-weighted imaging (DWI).

RESULTS

The mean preoperative tumor volume was 16.25 ± 17.6 cm3. Gross-total resection was achieved in 75%, near-total resection in 10%, and subtotal resection in 15% of patients. There was a small but not statistically significant increase in average FLAIR hyperintensity volume by 3.25 ± 10.51 cm3 (p = 0.16). The average postoperative volume of DWI high signal area with restricted diffusion on apparent diffusion coefficient maps was 8.35 ± 3.05 cm3. Assuming that the volume of restricted diffusion on DWI around tumor was 0 preoperatively, this represented a statistically significant increase on DWI (p < 0.001).

CONCLUSIONS

Although tubular retractors do not appear to significantly increase FLAIR signal in the brain, DWI intensity around the retractors can be identified. These data indicate that although tubular retractors may minimize damage to surrounding tissues, they still cause cytotoxic edema and cellular damage. Objective comparison against other retraction methods, as compared by 3D volumetric analysis or similar methods, will be important in determining the true advantage of tubular retractor systems.