Real time parallel intraoperative integration of endoscopic, microscopic, and navigation images: a proof of concept based on laboratory dissections

Benefits of endoscope-assisted microsurgery in the management of pediatric brain tumors

OBJECTIVE

Microsurgical and endoscopic techniques are vastly utilized in brain tumor surgery. Combining both techniques in the same procedure has different forms and applications. The aim of this work was to discuss the usefulness and describe the technical benefits of endoscope-assisted microsurgery (EAMS) in treating pediatric brain tumors in various anatomical locations.

METHODS

The medical records of 106 children who had undergone EAMS for brain tumors at Children's Cancer Hospital Egypt (CCHE-57357) between January 2009 and January 2017 were reviewed. The patients' ages ranged from 1 to 16 years (mean age 7.5 years). Technical variations, difficulties, complications, strategies, and extent of resection were addressed according to anatomical location.

RESULTS

In general, EAMS enabled closer inspection of tumor extension and surrounding vital structures, especially in the hidden corners not appreciable by the microscope alone, such as tumors in the internal auditory canal and cerebellopontine angle contents in 14 cases, all of which were totally excised, and the undersurface of the optic apparatus in 65 craniopharyngiomas. Total excision was achievable in 51 of the 65 craniopharyngiomas; residual tumor was intentionally left behind under endoscopic guidance in the remaining 14 patients to ensure better hypothalamic function. Vision improved in 15 of 16 patients who initially presented with visual defects. Only 4 patients had new-onset postoperative endocrinopathies. For intraventricular tumors, EAMS allowed earlier recognition of tumor pedicle and, hence, earlier control of the blood supply of the tumor and safer total excision of 12 lateral ventricle, 6 pineal and third ventricle, and 9 fourth ventricle tumors. The tandem use of the endoscope and microscope enabled safer tumor dissections that were performed with more confidence in situations in which pure microscopic excision was either not achievable or less safe. Technical strategies, pitfalls, difficulties, and precautions were categorized and described per tumor location.

CONCLUSIONS

EAMS of pediatric brain tumors is a promising, user-friendly tool that complements microsurgery in the management of these complex lesions. The benefits of 2D endoscopy are added to the benefits of stereoscopic perception. EAMS is especially helpful during the removal of different complex pediatric brain tumors. Simultaneous or tandem endoscopic and microscopic approaches may have the potential for better functional outcomes through better visualization and preservation of vital structures in corners that are hidden from the microscope.

Comparative analysis of surgical exposure and freedom between the subtonsillar, endoscope-assisted subtonsillar, and far-lateral approaches to the lower clivus: A cadaveric study

The far-lateral (FL)approach is a classic technique for skull base surgeries involving the lower clivus (LC).Recently, a modified suboccipital midline approach known as the subtonsillar (ST) approach, along with the endoscope-assisted subtonsillar (EST) approach, has been described as a minimally invasive technique to treat LC lesions. However, there is no quantitative study on comparing these approaches together for reaching LC. We aimed to compare surgical exposure and freedom provided by ST, EST, and FL approaches for various targets at LC. These approaches were performed on each side of five cadaveric specimens (total 10 sides), and relevant parameters were quantified and compared using a repeated measures ANOVA test. FL approach yielded the greatest surgical area (237.8 ± 56.0 mm²) and exposure, including lengths of glossopharyngeal nerve (16.2 ± 1.9 mm), hypoglossal nerve (11.4 ± 2.4 mm), vertebral artery (23.9 ± 3.3 mm), followed by EST and ST approaches. For surgical freedom, FL approach provided the greatest angle of attack (90.0 ± 14.0° at jugular foramen, 95.1 ± 15.8° at hypoglossal canal, 83.4 ± 31.4° at bifurcation point of posterior inferior cerebellar artery and vertebral artery). Our systematic comparison suggests that EST approach, compared to ST approach, can significantly increase surgical exposure to the medial side of LC, but FL approach still provides the greatest surgical exposure and freedom at LC. Despite the limitations of a cadaveric study, our quantitative data can update the literature on currently available surgical techniques for reaching LC and better inform preoperative planning in this area. Further studies should be performed to evaluate these approaches in clinical practice.

Modified Pure Endoscopic Approach to Pineal Region: Proof of Concept of Efficient and Inexpensive Surgical Model Based on Laboratory Dissections

OBJECTIVE

In recent decades endoscopic techniques have been increasingly used in neurosurgery as they may offer a valuable close-up view of the working area through a minimally invasive surgical corridor. Herein, we present an inexpensive and efficient endoscopic surgical model using a borescope, which was used for a "modified pure endoscopic approach" to the pineal region.

METHODS

A borescope video camera was connected to a 16-inch personal computer monitor. A standard midline suboccipital craniotomy was performed on 2 cadaveric heads in the Concorde position. Then, a "borescopic" supracerebellar infratentorial approach was executed, thus reaching the pineal region, which was exposed through an extensive arachnoid dissection.

RESULTS

Using the previously described model, we were able to provide excellent exposure of the main neurovascular structures of the pineal region, as shown by the intraoperative videos. In 1 specimen we identified an incidental pineal cyst that was meticulously dissected and removed.

CONCLUSIONS

Our proposed "borescopic" surgical model may represent an inexpensive and efficient alternative to conventional endoscopic techniques and could be used for training purposes, as well as even for clinical procedures, after a proper validation, particularly in economically challenging environments.

Supraorbital subfrontal trans-laminar endoscope-assisted approach for tumors of the posterior third ventricle

BACKGROUND

Different surgical approaches have been developed for dealing with third ventricle lesions, all aimed at obtaining a safe removal minimizing brain manipulation. The supraorbital subfrontal trans-lamina terminalis route, commonly employed only for the anterior third ventricle, could represent, in selected cases with endoscopic assistance, an alternative approach to posterior third ventricular lesions.

METHODS

Seven patients underwent a supraorbital subfrontal trans-laminar endoscope-assisted approach to posterior third ventricle tumors (two craniopharyngiomas, one papillary tumor of the pineal region, one pineocytoma, two neurocytomas, one glioblastoma). Moreover, a conventional third ventriculostomy was performed via the same trans-laminar approach in four cases.

RESULTS

Complete tumor removal was accomplished in four cases, subtotal removal in two cases, and a simple biopsy in one case. Adjuvant radiotherapy and/or chemotherapy was administered, if required, on the basis of the histologic diagnosis. No major complications occurred after surgery except for an intratumoral hemorrhage in a patient undergoing a biopsy for a glioblastoma, which simply delayed the beginning of adjuvant radiochemotherapy. No ventriculoperitoneal shunt placement was needed in these patients at the most recent clinical and radiologic session (average 39.57 months, range 13-85 months). Two illustrative cases are presented.

CONCLUSIONS

The supraorbital subfrontal trans-laminar endoscope-assisted approach may provide, in selected cases, an efficient and safe route for dealing with posterior third ventricular tumors.

Frameless Stereotactic Insertion of Viewsite Brain Access System with Microscope-Mounted Tracking Device for Resection of Deep Brain Lesions: Technical Report

The surgical management of deep brain tumors is often challenging due to the limitations of stereotactic needle biopsies and the morbidity associated with transcortical approaches. We present a novel microscopic navigational technique utilizing the Viewsite Brain Access System (VBAS) (Vycor Medical, Boca Raton, FL, USA) for resection of a deep parietal periventricular high-grade glioma as well as another glioma and a cavernoma with no related morbidity. The approach utilized a navigational tracker mounted on a microscope, which was set to the desired trajectory and depth. It allowed gentle continuous insertion of the VBAS directly to a deep lesion under continuous microscopic visualization, increasing safety by obviating the need to look up from the microscope and thus avoiding loss of trajectory. This technique has broad value for the resection of a variety of deep brain lesions.

Hybrid Microscopic-Endoscopic Surgery for Craniopharyngioma in Neurosurgical Suite: Technical Notes

OBJECTIVE

The best chance of curing craniopharyngioma is achieved by microsurgical total resection; however, its location adjacent to critical structures hinders complete resection without neurologic deterioration. Unrecognized residual tumor within microscopic blind spots might result in tumor recurrences. To improve outcomes, new techniques are necessary to visualize tissue within these blind spots. We examined the success of hybrid microscopic-endoscopic neurosurgery for craniopharyngioma in a neurosurgical suite.

METHODS

Four children with craniopharyngiomas underwent microscopic resection. When the neurosurgeon was confident that most of the visible tumor was removed but was suspicious of residual tumor within the blind spot, he or she used an integrated endoscope-holder system to inspect and remove any residual tumor. Two ceiling monitors were mounted side by side in front of the surgeon to display both microscopic and endoscopic views and to view both monitors simultaneously.

RESULTS

Surgery was performed in all patients via the frontobasal interhemispheric approach. Residual tumors were observed in the sella (2 patients), on the ventral surface of the chiasm and optic nerve (1 patient), and in the third ventricle (1 patient) and were resected to achieve total resection. Postoperatively, visual function was improved in 2 patients and none exhibited deterioration related to the surgery.

CONCLUSIONS

Simultaneous microscopic and endoscopic observation with the use of dual monitors in a neurosurgical suite was ergonomically optimal for the surgeon to perform microsurgical procedures and to avoid traumatizing surrounding vessels or neural tissues. Hybrid microscopic-endoscopic neurosurgery may contribute to safe, less-invasive, and maximal resection to achieve better prognosis in children with craniopharyngioma.

Maximizing the Petroclival Region Exposure Via a Suboccipital Retrosigmoid Approach: Where Is the Intrapetrous Internal Carotid Artery?

BACKGROUND

Recent reports have validated the use of retrosigmoid approach extensions to deal with petroclival lesions.

OBJECTIVE

To describe the topographic retrosigmoid anatomy of the intrapetrous internal carotid artery (IICA), providing guidelines for maximizing the petroclival region exposure via this route.

METHODS

The IICA was exposed bilaterally in 6 specimens via a retrosigmoid approach in the semisitting position. Its topographic relationship with pertinent posterolateral cranial base landmarks was quantified with neuronavigation.

RESULTS

Safe exposure of the IICA and the surrounding inframeatal/petroclival regions was accomplished in all specimens. On average, the IICA genu was 15.08 mm anterolateral to the XI nerve in the jugular foramen, 16.18 mm anteroinferolateral to the endolymphatic sac, and 10.63 mm anteroinferolateral to the internal acoustic meatus. On average, the IICA horizontal segment was 9.92 mm inferolateral to the Meckel cave, and its midpoint was 19.96 mm anterolateral to the XI nerve in the jugular foramen. The mean distance from the IICA genu to the cochlea was 1.96 mm. The genu and the midpoint of the horizontal segment of the IICA were exposed at a depth of approximately 14.50 mm from the posterior pyramidal wall with the use of different drilling angles (49.74° vs 39.54°, respectively).

CONCLUSION

Knowledge of the IICA general relationship with these landmarks (combined with a careful assessment of the preoperative imaging and with the use of intraoperative navigation and micro-Doppler) may help to enhance the inframeatal/petroclival region exposure via a retrosigmoid route, maximizing safe inframeatal and suprameatal petrous bone removal while minimizing neurovascular complications.

Microsurgical and Endoscopic Anatomy of the Extended Retrosigmoid Inframeatal Infratemporal Approach

BACKGROUND

Different and often complex routes are available to deal with jugular foramen tumors with extracranial extension.

OBJECTIVE

To describe a novel extension of the retrosigmoid approach useful to expose the extracranial area abutting the posterior fossa skull base.

METHODS

A navigation-guided, endoscope-assisted retrosigmoid inframeatal approach was performed on 6 cadaveric heads in the semisitting position, displaying an area from the internal acoustic meatus to the lower cranial nerves and exposing the intrapetrous internal carotid artery. We then continued removing the temporal bone located between the sigmoid sinus and the hearing apparatus, reaching the infratemporal area just lateral to the jugular fossa. This drilling, which we refer to as posterolateral inframeatal drilling, has not previously been described. Drilling of the horizontal segment of the occipital squama allowed good visualization of the uppermost cervical internal carotid artery, internal jugular vein, and lower extracranial cranial nerves.

RESULTS

We were able to provide excellent exposure of the inframeatal area and of the posterior infratemporal fossa from different operative angles, preserving the neurovascular structures and the labyrinth in all specimens. The intradural operative window on the extracranial compartment was limited by the venous sinuses and the hearing apparatus and presented a mean width of 8.52 mm. Sigmoid sinus transection led to better visualization of the lateral half of the jugular foramen and of the uppermost cervical internal carotid artery.

CONCLUSION

The navigation-guided endoscope-assisted extended retrosigmoid inframeatal infratemporal approach provides an efficient and versatile route for resection of jugular foramen tumors with extracranial extension.

Recurrent atlantoaxial synovial cyst resection via a navigation-guided, endoscope-assisted posterior approach

Background:

Atlantoaxial cysts are rare, and only 46 histologically confirmed cases have been reported.

Case Description:

A 75-year-old male presented 2 years ago with headache, neck pain, loss of balance, and episodic dysphagia, for which he had undergone posterior cervical drainage of a left-sided atlantoaxial cyst. Although his original symptoms resolved, they recurred 2 years later and were correlated with an enhanced MR that showed a recurrent left C1-C2 synovial cyst causing marked cervical cord compression. It was successfully resected through a navigation-guided, endoscope-assisted posterior approach. The patient's symptoms/signs resolved completely, and he has remained symptom-free for over 30 months postoperatively, with no evidence of recurrence on MR or craniocervical instability.

Conclusions:

A patient who successfully underwent resection of a recurrent synovial cervical cyst using a navigation-guided, endoscope-assisted posterior approach has been reported here.

Successful resection of anterior and anterolateral lesions at the craniovertebral junction using a simple posterolateral approach

Tumors at the craniovertebral junction (CVJ) often present a challenge due to proximity to vital neurovascular structures. In the last few decades, many authors have proposed complex surgical approaches to access pathologies located anterior or anterolateral to the CVJ with the hopes of reducing morbidity. We propose that the simple posterolateral approach in a semi-sitting position can be used to resect most anterior and anterolateral CVJ tumors safely and effectively. We retrospectively reviewed the clinical series of 10 patients treated by the senior author using the posterolateral suboccipital approach to treat anterior or anterolateral CVJ pathologies. We describe our surgical techniques, outcomes, and present illustrative patients. Gross total resection was achieved in eight patients (80%). Good functional outcome (Glasgow Outcome Scale 4-5) was obtained in all patients. Preoperative symptoms and deficits were improved (78%) or stable (22%) in all patients. There was one (10%) surgical complication that was cerebrospinal fluid leak requiring reoperation. There was no permanent morbidity or mortality in this series. There were two (20%) medical complications including deep vein thrombosis and pulmonary embolus. There were three (30%) transient neurologic complications, dysphagia in two and dysarthria in one, all of which resolved completely in early follow-up. The majority of anterior or anterolateral CVJ lesions can be successfully removed using the simple posterolateral approach.