Endoscopic and Gravity-Assisted Resection of Medial Temporo-occipital Lesions Through a Supracerebellar Transtentorial Approach: Technical Notes With Case Illustrations

Critical appraisal of minimally invasive keyhole surgery for intracranial meningioma in a large case series

Background

Meningioma surgery has evolved over the last 20 years with increased use of minimally invasive approaches including the endoscopic endonasal route and endoscope-assisted and gravity-assisted transcranial approaches. As the “keyhole” concept remains controversial, we present detailed outcomes in a cohort series.

Methods

Retrospective analysis was done for all patients undergoing meningioma removal at a tertiary brain tumor referral center from 2008–2021. Keyhole approaches were defined as: use of a minimally invasive “retractorless” approach for a given meningioma in which a traditional larger approach is often used instead. The surgical goal was maximal safe removal including conservative (subtotal) removal for some invasive locations. Primary outcomes were resection rates, complications, length of stay and Karnofsky Performance Scale (KPS). Secondary outcomes were endoscopy use, perioperative treatments, tumor control and acute MRI FLAIR/T2 changes to assess for brain manipulation and retraction injury.

Results

Of 329 patients, keyhole approaches were utilized in 193(59%) patients (mean age 59±13; 30 (15.5%) had prior surgery) who underwent 213 operations; 205(96%) were skull base location. Approaches included: endoscopic endonasal (n = 74,35%), supraorbital (n = 73,34%), retromastoid (n = 38,18%), mini-pterional (n = 20,9%), suboccipital (n = 4,2%), and contralateral transfalcine (n = 4,2%). Primary outcomes: Gross total/near total (>90%) resection was achieved in 125(59%) (5% for petroclival, cavernous sinus/Meckel’s cave, spheno-cavernous locations vs 77% for all other locations). Major complications included: permanent neurological worsening 12(6%), CSF leak 2(1%) meningitis 2(1%). There were no DVTs, PEs, MIs or 30-day mortality. Median LOS decreased from 3 to 2 days in the last 2 years; 94% were discharged to home with favorable 90-day KPS in 176(96%) patients. Secondary outcomes: Increased FLAIR/T2 changes were noted on POD#1/2 MRI in 36/213(17%) cases, resolving in all but 11 (5.2%). Endoscopy was used in 87/139(63%) craniotomies, facilitating additional tumor removal in 55%. Tumor progression occurred in 26(13%) patients, mean follow-up 42±36 months.

Conclusions & relevance

Our experience suggests minimally invasive keyhole transcranial and endoscopic endonasal meningioma removal is associated with comparable resection rates and low complication rates, short hospitalizations and high 90-day performance scores in comparison to prior reports using traditional skull base approaches. Subtotal removal may be appropriate for invasive/adherent meningiomas to avoid neurological deficits and other post-operative complications, although longer follow-up is needed. With careful patient selection and requisite experience, these approaches may be considered reasonable alternatives to traditional transcranial approaches.

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.

Supracerebellar Transtentorial Approach for Occipital Meningioma to Maximize Visual Preservation: Technical Note

BACKGROUND AND IMPORTANCE

Surgery for resection of tentorial meningiomas compressing primary visual cortex carries a significant risk of worsening vision. This concern is especially acute in patients with a preexisting visual deficit. Approaches that involve mechanical retraction of the occipital lobe further threaten visual function. The supracerebellar transtentorial (SCTT) approach, which does not carry a risk of occipital retraction injury, should be considered for patients with occipital tentorial meningiomas to maximize functional visual outcomes.

CLINICAL PRESENTATION

A 54-yr-old woman underwent 2 resections and radiation therapy for a right occipital oligodendroglioma as a teenager. She was left with a complete left homonymous hemianopsia. The patient now presented with progressive vision loss in her remaining right visual field. Imaging revealed a left occipital superiorly projecting tentorial meningioma. To preserve her remaining visual function the SCTT approach was chosen for resection. A Simpson grade 1 removal was achieved without disrupting the occipital lobe pia or requiring mechanical cerebellar retraction. A diagnosis of a WHO grade II meningioma (presumably radiation induced) was made. The patient's vision returned to premorbid baseline 1 wk after surgery.

CONCLUSION

The SCTT approach should be considered for the surgical management of patients with occipital tentorial meningiomas when visual preservation is at risk. This approach avoids transgression of visual cortex and minimizes the risk of venous infarction or contusions from retraction injury.

Microsurgical Endoscope-Assisted Gravity-Aided Transfalcine Approach for Contralateral Metastatic Deep Medial Cortical Tumors

BACKGROUND

Traditional approaches to deep medial cortical tumors utilize transcortical or ipislateral interhemispheric approaches, which can result in cortical damage or retraction injury. To reduce these risks, the microscopic transfalcine approach has been previously described.

OBJECTIVE

To describe this approach performed with endoscopic assistance for metastatic tumor resection, demonstrating appropriate and safe tumor resection without injury to the contralateral hemisphere.

METHODS

Eleven consecutive patients harboring medial, deep metastatic tumors are reported. Tumor resection was performed with endoscopic assistance with 2 surgeons. Clinical outcomes are recorded.

RESULTS

All 11 patients underwent safe tumor resection. Gross total resection was achieved in 73% of patients. The application of the angled endoscope allowed for further tumor resection in 91% of patients. There were no complications in these patients. The contralateral brain did not demonstrate clinical or radiographic injury as well.

CONCLUSION

This series suggests that the endoscopic transfalcine approach in the lateral position can be a safe and effective approach for resecting medial interhemispheric metastatic tumors. It allows excellent tumor visualization, eliminates the need for brain retraction, minimizes parenchymal transgression, and improves surgical ergonomics. A familiarity of endoscopy and neuroanesthesia support is helpful when utilizing this approach.