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.

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.

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.

Transulcal parafascicular minimally invasive approach to deep and subcortical cavernomas: technical note

Cavernomas comprise 8%-15% of intracranial vascular lesions, usually supratentorial in location and superficial. Cavernomas in the thalamus or subcortical white matter represent a unique challenge for surgeons in trying to identify and then use a safe corridor to access and resect the pathology. Previous authors have described specific open microsurgical corridors based on pathology location, often with technical difficulty and morbidity. This series presents 2 cavernomas that were resected using a minimally invasive approach that is less technically demanding and has a good safety profile. The authors report 2 cases of cavernoma: one in the thalamus and brainstem with multiple hemorrhages and the other in eloquent subcortical white matter. These lesions were resected through a transulcal parafascicular approach with a port-based minimally invasive technique. In this series there was complete resection with no neurological complications. The transulcal parafascicular minimally invasive approach relies on image interpretation and trajectory planning, intraoperative navigation, cortical cannulation and subcortical space access, high-quality optics, and resection as key elements to minimize exposure and retraction and maximize tissue preservation. The authors applied this technique to 2 patients with cavernomas in eloquent locations with excellent outcomes.

Comparison of endoscope- versus microscope-assisted resection of deep-seated intracranial lesions using a minimally invasive port retractor system

OBJECT

Tubular brain retractors may improve access to deep-seated brain lesions while potentially reducing the risks of collateral neurological injury associated with standard microsurgical approaches. Here, microscope-assisted resection of lesions using tubular retractors is assessed to determine if it is superior to endoscope-assisted surgery due to the technological advancements associated with modern tubular ports and surgical microscopes.

METHODS

Following institutional approval of the tubular port, data obtained from the initial 20 patients to undergo transportal resection of deep-seated brain lesions were analyzed in this study. The pathological entities of the resected tissues included metastatic tumors (8 patients), glioma (7), meningioma (1), neurocytoma (1), radiation necrosis (1), primitive neuroectodermal tumor (1), and hemangioblastoma (1). Surgery incorporated endoscopic (5 patients) or microscopic (15) assistance. The locations included the basal ganglia (11 patients), cerebellum (4), frontal lobe (2), temporal lobe (2), and parietal lobe (1). Cases were reviewed for neurological outcomes, extent of resection (EOR), and complications. Technical data for the port, surgical microscope, and endoscope were analyzed.

RESULTS

EOR was considered total in 14 (70%), near total (> 95%) in 4 (20%), and subtotal (< 90%) in 2 (10%) of 20 patients. Incomplete resection was associated with the basal ganglia location (p < 0.05) and use of the endoscope (p < 0.002). Four of 5 (80%) endoscope-assisted cases were near-total (2) or subtotal (2) resection. Histopathological diagnosis, presenting neurological symptoms, and demographics were not associated with EOR. Complication rates were low and similar between groups.

CONCLUSIONS

Initial experience with tubular retractors favors use of the microscope rather than the endoscope due to a wider and 3D field of view. Improved microscope optics and tubular retractor design allows for binocular vision with improved lighting for the resection of deep-seated brain lesions.

Pure Neuroendoscopic Resection of Cystic Cerebellar Tumors

BACKGROUND

We describe the resection of cerebellar cystic tumors using pure neuroendoscopy. This technique consists of performing all of the procedures under an endoscopic view, with the instruments introduced into the operative field coaxially to the endoscope through a trocar.

CASE DESCRIPTION

Three cases of cerebellar cystic lesions (two pilocytic astrocytomas and one hemangioblastoma) were approached using the pure neuroendoscopic technique. Under general anesthesia and prone positioning, a suboccipital burr hole was created. The endoscope was introduced into the tumor cavity, and a reddish nodule was identified. The monopolar electrode was used to coagulate and dissect the surrounding nodular tissue. Grasping forceps were used to remove the nodule. There were no complications related to tumor removal, and the patients recovered from their symptoms. The follow-up images showed reduction of the cavity with no contrast enhancement.

CONCLUSION

The pure neuroendoscopic technique was shown to be minimally invasive and a successful and secure method to treat cystic cerebellar tumors.

Endoscopic approaches to brainstem cavernous malformations: Case series and review of the literature

Background:

Symptomatic cavernous malformations involving the brainstem are frequently difficult to access via traditional methods. Conventional skull-base approaches require significant brain retraction or bone removal to provide an adequate operative corridor. While there has been a trend toward limited employment of the most invasive surgical approaches, recent advances in endoscopic technology may complement existing methods to access these difficult to reach areas.

Case Descriptions:

Four consecutive patients were treated for symptomatic, hemorrhagic brainstem cavernous malformations via fully endoscopic approaches (endonasal, transclival; retrosigmoid; lateral supracerebellar, infratentorial; endonasal, transclival). Together, these lesions encompassed all three segments of the brainstem. Three of the patients had complete resection of the cavernous malformation, while one patient had stable residual at long-term follow up. Associated developmental venous anomalies were preserved in the two patients where one was identified preoperatively. Three of the four patients maintained stable or improved neurological examinations following surgery, while one patient experienced ipsilateral palsies of cranial nerves VII and VIII. The first transclival approach resulted in a symptomatic cerebrospinal fluid leak requiring re-operation, but the second did not. Although there are challenges associated with endoscopic approaches, relative to our prior microsurgical experience with similar cases, visualization and illumination of the surgical corridors were superior without significant limitations on operative mobility.

Conclusion:

The endoscope is a promising adjunct to the neurosurgeon's ability to approach difficult to access brainstem cavernous malformations. It allows the surgeon to achieve well-illuminated, panoramic views, and by combining approaches, can provide minimally invasive access to most regions of the brainstem.

Combined awake craniotomy with endoscopic port surgery for resection of a deep-seated temporal lobe glioma: a case report

The authors describe the combination of awake craniotomy and minimally invasive endoscopic port surgery to resect a high-grade glioma located near eloquent structures of the temporal lobe. Combined minimally invasive techniques such as these may facilitate deep tumor resection within eloquent regions of the brain, allowing minimum white matter dissection. Technical aspects of this procedure, a case outcome involving this technique, and the direction of further investigations for the utility of these techniques are discussed.