Cottonoid-guided intraoperative ultrasonography in neurosurgery: a proof-of-concept single surgeon case series

Revisiting the combined approach of Yaşargil for microsurgical removal of intra-extraventricular and pure intraventricular craniopharyngiomas

OBJECTIVE

Craniopharyngiomas originate from squamous epithelium in the pituitary stalk, tend to expand into surrounding tissues, and have high recurrence rates when residual tumor remains. Therefore, gross total resection should be the goal at initial surgery. Yaşargil described the combined approach, involving both anterior interhemispheric transcallosal transforaminal and pterional transsylvian approaches in the same session for intra-extraventricular and pure intraventricular craniopharyngiomas. This study presents our series, the first since Yaşargil's publications, of patients operated on with this approach.

METHODS

Data were prospectively collected (September 2006-August 2024) from patients undergoing endoscope-assisted combined craniopharyngioma surgery. First, parasagittal craniotomy was performed, and the tumor was resected microsurgically via the anterior interhemispheric transcallosal transforaminal route. Then, the residual tumor in the parachiasmatic area was removed via the pterional craniotomy and transsylvian route. Since January 2018, intraoperative MRI has been used to confirm gross total resection.

RESULTS

During the study period, 67 craniopharyngioma patients underwent surgery, and combined approach was performed in 12 cases. Gross total resection was achieved in 11 of the 12 patients who underwent the combined approach, while one had a near-total resection. The patient who underwent near-total resection had a history of two prior surgeries and radiotherapy and was the only case of recurrence (mean follow-up: 97 months). The stalk was resected in all patients and hormone replacement therapy was required.

CONCLUSION

The basic principle in the treatment of craniopharyngiomas, which have high recurrence rates in the presence of residual tumor and locally aggressive behavior, is gross total resection in the initial surgery. Gross total resection offers the opportunity for cure and is critical in the course of the disease. The combined approach is an effective and safe technique to achieve gross total resection in the initial surgery for patients with intra-extraventricular and pure intraventricular craniopharyngiomas.

Tailored Callosotomy in Third Ventricle Colloid Cyst Resection via Anterior Interhemispheric Transcallosal Approach

BACKGROUND

The colloid cyst represents a relatively uncommon intracranial lesion. It garners significant attention from neurosurgeons due to its benign nature, deep-seated location, and promising prognosis when identified early and surgically removed. A variety of surgical methods are used to treat these cysts, each with their strengths and weaknesses. The aim of this study is to introduce and assess a precise microsurgical technique for managing colloid cysts using the anterior interhemispheric transcallosal approach.

METHODS

The research involved a retrospective analysis of 14 cases between 2021 and 2023 treated with the anterior interhemispheric transcallosal approach by 2 experienced skull base surgeons. The evaluation encompassed demographic, clinical, radiological, histological, and surgical data. Additionally, the colloid cyst risk score was used to assess the risk of obstructive hydrocephalus. The procedure incorporated neuronavigation and ultrasound to determine the precise entry point and to plan the trajectory.

RESULTS

The minimally invasive microsurgical technique was effectively employed in all 14 cases, with no reported postoperative complications. Postsurgery magnetic resonance imaging scans confirmed complete cyst removal, with an average callosotomy measurement of 5.4 ± 2.5 mm. Importantly, none of the patients experienced disconnection syndrome associated with callosotomy.

CONCLUSIONS

The adapted microsurgical approach via the anterior interhemispheric transcallosal method emerges as a secure and efficient way to address colloid cysts. It ensures comprehensive cyst removal while minimizing complications, boasting advantages such as reduced invasiveness, enhanced visibility, and minimal tissue disturbance, thereby confirming its role in colloid cyst surgical interventions.

Intraoperative ultrasonography in microsurgical resection of vestibular schwannomas via retrosigmoid approach: surgical technique and proof-of-concept illustrative case series

PURPOSE

Intraoperative ultrasonography (ioUS) is an established tool for the real-time intraoperative orientation and resection control in intra-axial oncological neurosurgery. Conversely, reports about its implementation in the resection of vestibular schwannomas (VS) are scarce. The aim of this study is to describe the role of ioUS in microsurgical resection of VS.

METHODS

ioUS (Craniotomy Transducer N13C5, BK5000, B Freq 8 MHz, BK Medical, Burlington, MA, USA) is integrated into the surgical workflow according to a 4-step protocol (transdural preresection, intradural debulking control, intradural resection control, transdural postclosure). Illustrative cases of patients undergoing VS resection through a retrosigmoid approach with the use of ioUS are showed to illustrate advantages and pitfalls of the technique.

RESULTS

ioUS allows clear transdural identification of the VS and its relationships with surgically relevant structures of the posterior fossa and of the cerebellopontine cistern prior to dural opening. Intradural ioUS reliably estimates the extent of tumor debulking, thereby helping in the choice of the right moment to start peripheral preparation and in the optimization of the extent of resection in those cases where subtotal resection is the ultimate goal of surgery. Transdural postclosure ioUS accurately depicts surgical situs.

CONCLUSION

ioUS is a cost-effective, safe, and easy-to-use intraoperative adjunctive tool that can provide a significant assistance during VS surgery. It can potentially improve patient safety and reduce complication rates. Its efficacy on clinical outcomes, operative time, and complication rate should be validated in further studies.

Enhancing the Reliability of Intraoperative Ultrasound in Pediatric Space-Occupying Brain Lesions

INTRODUCTION

Intraoperative ultrasound (IOUS) may aid the resection of space-occupying brain lesions, though technical limits may hinder its reliability.

METHODS

IOUS (MyLabTwice^®, Esaote, Italy) with a microconvex probe was utilized in 45 consecutive cases of children with supratentorial space-occupying lesions aiming to localize the lesion (pre-IOUS) and evaluate the extent of resection (EOR, post-IOUS). Technical limits were carefully assessed, and strategies to enhance the reliability of real-time imaging were accordingly proposed.

RESULTS

Pre-IOUS allowed us to localize the lesion accurately in all of the cases (16 low-grade gliomas, 12 high-grade gliomas, eight gangliogliomas, seven dysembryoplastic neuroepithelial tumors, five cavernomas, and five other lesions, namely two focal cortical dysplasias, one meningioma, one subependymal giant cell astrocytoma, and one histiocytosis). In 10 deeply located lesions, IOUS with hyperechoic marker, eventually coupled with neuronavigation, was useful to plan the surgical route. In seven cases, the administration of contrast ensured a better definition of the vascular pattern of the tumor. Post-IOUS allowed the evaluation of EOR reliably in small lesions (<2 cm). In large lesions (>2 cm) assessing EOR is hindered by the collapsed surgical cavity, especially when the ventricular system is opened, and by artifacts that may simulate or hide residual tumors. The main strategies to overcome the former limit are inflation of the surgical cavity through pressure irrigation while insonating, and closure of the ventricular opening with Gelfoam before insonating. The strategies to overcome the latter are avoiding the use of hemostatic agents before IOUS and insonating through normal adjacent brain instead of corticotomy. These technical nuances enhanced the reliability of post-IOUS, with a total concordance to postoperative MRI. Indeed, the surgical plan was changed in about 30% of cases, as IOUS showed a residual tumor that was left behind.

CONCLUSION

IOUS ensures reliable real-time imaging in the surgery of space-occupying brain lesions. Limits may be overcome with technical nuances and proper training.