A Novel Dissection Method Using a Flexible Neuroendoscope for Resection of Tumors Around the Aqueduct of Sylvius

Considerations on surgical strategies and associated risk profiles for endoscopic tumor biopsies within the third ventricle and periaqueductal region

INTRODUCTION

Neuroendoscopic techniques have proven to be a successful and minimally-invasive technique for tumor biopsies within the third ventricle in pediatric patients. However, a comprehensive assessment of associated surgical strategies, techniques, and morbidity is essential to optimize patient outcomes.

METHODS

This retrospective study analyzed full endoscopic tumor biopsies in pediatric patients with tumors in the third ventricle and periaqueductal region. Data from 1995 to 2022 were collected from medical records, imaging, and intraoperative video documentation.

RESULTS

In this study, 16 shear endoscopic tumor biopsies were performed using the transventricular transforaminal approach. Tumors were located in the anterior or mid part of the third ventricle (50%) or in the periaqueductal and pineal recess region (50%). Preoperative hydrocephalus was seen in 81.25%. Tumor biopsies were harvested successfully in all cases. Simultaneous ETV was performed in 12 (75%) cases and additional septostomy in 3 (18.75%). Significant intraoperative bleeding occurred in 3 cases (18.75%). All bleeding situations could be successfully managed with continuous irrigation. Histopathology revealed astrocytoma as the predominant diagnosis (75%). No new neurologic deficits were observed, except for one case of transient oculomotor nerve paralysis after ETV. Hydrocephalus persisted in 18.6% of all cases with the need of urgent ventriculoperitoneal shunting in two patients.

CONCLUSION

In conclusion, neuroendoscopy emerges as an effective technique for tumor biopsies within the third ventricle in pediatric patients, offering the added advantage of simultaneous treatment of obstructive hydrocephalus. However, it is essential to acknowledge the specific intra- and postoperative risks associated with various surgical strategies. The safe management and achievement of favorable clinical results demand extensive experience and expertise.

Primary central nervous system lymphoma of the tectal plate in adult

Background:

Primary central nervous system lymphoma (PCNSL) originating in the brainstem is uncommon. In particular, PCNSL confined to the tectal plate in adults has never been reported in the past. The case of a 53-year-old man who was diagnosed with PCNSL in the tectal plate is reported.

Case Description:

The patient was referred to our hospital with a 1-month history of disorientation and magnetic resonance imaging showed hydrocephalus with an enhancing lesion in the tectum. Preoperative blood tests showed a high serum soluble interleukin-2 receptor level of 624 U/ml. Through a single burr hole, endoscopic third ventriculostomy and biopsy of the lesion were simultaneously performed with a flexible endoscope. The histological examination confirmed diffuse large B-cell lymphoma. The patient underwent chemotherapy and radiotherapy.

Conclusion:

Malignant lymphoma of the tectum may occur in adults. By measuring the soluble interleukin-2 level preoperatively, it was possible to include malignant lymphoma in the differential diagnosis. In addition, the use of a neuroendoscope permits biopsy and hydrocephalus treatment to be performed simultaneously.

Endoscopic excision of an aqueduct of Sylvius cavernoma causing obstructive hydrocephalus: technical note

BACKGROUND AND IMPORTANCE

Acquired lesions within the aqueduct of Sylvius are rare and their surgical management is challenging. Open transcranial approaches require dissection and manipulation of surrounding eloquent structures. Use of an endoscope can avoid potential morbidity from traversing and handling eloquent structures during open approaches whilst providing better visualisation of an intraventricular lesion.

CLINICAL PRESENTATION

A 62-year-old female presented with insidious onset short-term memory loss, unsteady gait, urinary incontinence and left-sided dysaesthesia. Magnetic resonance imaging (MRI) revealed hydrocephalus from an obstructive haemorrhagic lesion consistent with a cavernoma at the central midbrain within the aqueduct of Sylvius. An endoscopic approach was selected to provide optimal visualisation of the lesion. As only a single instrument could be accommodated, rotational movements were employed to tease out the lesion. Gross total resection was achieved. Her symptoms improved immediately postoperatively and she made a complete recovery by 2 months. Post-operative MRI showed resolution of hydrocephalus and no evidence of residual/recurrence of the lesion. Unfortunately, she developed hydrocephalus 3 months post-op and required placement of a ventriculoperitoneal shunt.

CONCLUSIONS

Endoscopic resection is safe and feasible for selected periaqueductal lesions as it provides direct access while minimising disruption of the surrounding anatomical structures. The limitation of only having a single instrument can be overcome by employing rotational movements.

The extreme anterior interhemispheric transcallosal approach for pure aqueduct tumors: surgical technique and case series

Purely aqueductal tumors represent a rare but distinct entity of neoplasms with characteristic morphology and clinical presentation. This study aims to describe the extreme anterior interhemispheric transcallosal approach as a surgical option for purely aqueductal tumors in the upper part of the cerebral aqueduct and present the surgical results. Prospectively collected data of 4 patients undergoing the extreme anterior interhemispheric transcallosal approach for purely aqueductal tumors in the upper cerebral aqueduct was analyzed. The technique is a variation of the anterior interhemispheric transcallosal approach. The callosotomy is placed at the transition between the body and genu of the corpus callosum, allowing an approach steep enough to reach through the foramen of Monro to the upper cerebral aqueduct without opening the choroidal fissure. All patients had preoperative, and intraoperative or immediate postoperative 3-T magnetic resonance imaging, and underwent examination at admission, after surgery, at discharge, and 3 months postoperatively. Patient data are reported according to common descriptive statistics. All patients harbored low-grade gliomas causing hydrocephalus. Complete resection was achieved without mortality or morbidity. All patients recovered and presented neurologically intact at the 3-month postoperative follow-up. None had recurrence or needed adjuvant therapy. The extreme anterior interhemispheric transcallosal approach proved to be effective and safe. This approach does not require manipulation of the choroidal fissure or disrupt healthy brain parenchyma (except for a small callosotomy). We propose it as an option for removing a purely aqueductal tumor in the upper cerebral aqueduct with associated hydrocephalus.

Resection of a recurrent medulloblastoma in the anterior middle part of the aqueduct with a flexible endoscope: a case report

Resection or biopsy of intraventricular brain tumors using an endoscope has become common, but the limitations of these procedures are not clear. Manipulation to access a tumor that arises from the blind angle of the rigid endoscope, such as the anterior part of the aqueduct, is limited. We report here that we successfully resected a recurrent medulloblastoma in the anterior part of the aqueduct using only a flexible endoscope. This method appears to be suitable for poorly vascularized and suctionable tumors that arise in the blind angle of a rigid endoscope.

Importance of Hydrostatic Pressure and Irrigation for Hemostasis in Neuroendoscopic Surgery

Recently neurosurgical operations have been carried out with water irrigation such as endoscopic third ventriculostomy and tumor resections in ventricles. Water irrigation is one of several published methods that promote hemostasis; however, not enough experimental evidence exists on its efficacy. In this study, we investigate whether hydrostatic pressure and persistent irrigation promote hemostasis in neuroendoscopic surgery. We dissected tails of 12-16-week-old C57BL/6 male mice at 5 mm proximal from the tip and checked for bleeding times under dry and wet conditions at pressures of 0 cmH₂O, 10 cmH₂O, 15 H₂O, and 20 cmH₂O without persistent irrigation to bleeding point and 10 cmH₂O with persistent irrigation. We then examined the dissected edge with hematoxylin-eosin staining and measured the size of vessels. The average bleeding time of each group is as follows: dry: 203.4 sec, wet: 164.4 sec, 5 cmH₂O: 138.6 sec, 10 cmH₂O: 104.6 sec (P <0.001), 20 cmH₂O: 56 sec (P <0.001), and 10 cmH₂O with persistent irrigation: 72.8 sec (P <0.01 compared to 10 cmH₂O without persistent irrigation). The maximum caliber of mice's tail artery was 50-60 μm. Hydrostatic pressure and irrigation are important factors contributing to hemostasis.

Pediatric Central Nervous System Tumors: State-of-the-Art and Debated Aspects

Pediatric neuro-oncology surgery continues to progress in sophistication, largely driven by advances in technology used to aid the following aspects of surgery: operative planning (advanced MRI techniques including fMRI and DTI), intraoperative navigation [preoperative MRI, intra-operative MRI (ioMRI) and intra-operative ultrasound (ioUS)], tumor visualization (microscopy, endoscopy, fluorescence), tumor resection techniques (ultrasonic aspirator, micro-instruments, micro-endoscopic instruments), delineation of the resection extent (ioMRI, ioUS, and fluorescence), and intraoperative safety (neurophysiological monitoring, ioMRI). This article discusses the aforementioned technological advances, and their multimodal use to optimize safe pediatric neuro-oncology surgery.