Fully neuroendoscopic resection of cerebellopontine angle tumors through a retrosigmoid approach: a retrospective single-center study

The objective of this study is to preliminarily investigate the surgical safety, efficacy, techniques, and clinical value of fully neuroendoscopic surgery for the resection of cerebellopontine angle (CPA) tumors via a retrosigmoid approach. The clinical data of 47 cerebellopontine angle area (CPA) tumors that were treated by full neuroendoscopic surgery from June 2014 to June 2023 were retrospectively analyzed. The efficacy and advantages of the surgical techniques were evaluated based on indicators such as duration of the surgery, neuroendoscopic techniques, intraoperative integrity of nerves and blood vessels, extent of tumor resection, outcomes or postoperative symptoms, and incidence of complications. The 47 cases of cerebellopontine angle tumors include 34 cases of epidermoid cysts, 7 cases of vestibular schwannomas, and 6 cases of meningiomas. All patients underwent fully neuroendoscopic surgery. Twenty tumors were removed using the one-surgeon two-hands technique, and 27 tumors were removed using the two-surgeons four-hands technique. The anatomical integrity of the affected cranial nerves was preserved in all 47 cases. None of the patients suffered a postoperative hemorrhage, cerebrospinal fluid leak, and aseptic or septic meningitis, or died. The rate of total tumor resection was 72.3% (34/47), and the symptom improvement rate was 89.4% (42/47). All patients were followed up for 2 to 12 months, and none died nor showed any signs of tumor recurrence. By analyzing 47 fully neuroendoscopic resections of CPA tumors using the posterior sigmoid sinus approach in our center, we believe that such method allows complete, safe, and effective resection of CPA tumors and is thereby worthy of clinical promotion.

Endoscope-Assisted Middle Fossa Approach: Optimizing the Surgical Corridor for the Resection of Multicompartmental Chordomas

Background  Skull base chordomas are a major therapeutic challenge. The surgical management involves selecting an approach that will offer the patient the best chance of largest/complete removal while minimizing morbidity and mortality. Methods  Medical records and imaging review of two skull base chordomas involving the middle fossa and posterior fossa that were successfully treated with an endoscope-assisted middle fossa approach. Results  The use of angled endoscopes provided better identification of anatomical landmarks and improved tumor resection when compared with the microscopic surgical exposure. The approach selection, anatomical landmarks, and technical aspects of the intraoperative setting of the endoscope-assisted approach are discussed. Conclusion  Endoscopic assistance in the middle fossa approach is a safe and valuable tool for maximizing the reach of the surgical corridor when treating skull base chordomas.

Surgery of the lateral skull base: a 50-year endeavour

Disregarding the widely used division of skull base into anterior and lateral, since the skull base should be conceived as a single anatomic structure, it was to our convenience to group all those approaches that run from the antero-lateral, pure lateral and postero-lateral side of the skull base as “Surgery of the lateral skull base”. “50 years of endeavour” points to the great effort which has been made over the last decades, when more and more difficult surgeries were performed by reducing morbidity. The principle of lateral skull base surgery, “remove skull base bone to approach the base itself and the adjacent sites of the endo-esocranium”, was then combined with function preservation and with tailoring surgery to the pathology. The concept that histology dictates the extent of resection, balancing the intrinsic morbidity of each approach was the object of the first section of the present report. The main surgical approaches were described in the second section and were conceived not as a step-by-step description of technique, but as the highlighthening of the surgical principles. The third section was centered on open issues related to the tumor and its treatment. The topic of vestibular schwannoma was investigated with the current debate on observation, hearing preservation surgery, hearing rehabilitation, radiotherapy and the recent efforts to detect biological markers able to predict tumor growth. Jugular foramen paragangliomas were treated in the frame of radical or partial surgery, radiotherapy, partial “tailored” surgery and observation. Surgery on meningioma was debated from the point of view of the neurosurgeon and of the otologist. Endolymphatic sac tumors and malignant tumors of the external auditory canal were also treated, as well as chordomas, chondrosarcomas and petrous bone cholesteatomas. Finally, the fourth section focused on free-choice topics which were assigned to aknowledged experts. The aim of this work was attempting to report the state of the art of the lateral skull base surgery after 50 years of hard work and, above all, to raise questions on those issues which still need an answer, as to allow progress in knowledge through sharing of various experiences. At the end of the reading, if more doubts remain rather than certainties, the aim of this work will probably be achieved.

Combined microsurgical and endoscopic technique for removal of extensive intracranial epidermoids

Background

Intracranial epidermoid tumors are challenging lesions because they grow along the subarachnoid spaces around delicate neurovascular structures and often extend from one compartment to another. The purpose of this study was to determine the usefulness of endoscopic assistance in the microsurgical resection of these lesions, in which total resection is therapy of choice.

Methods

A total of 48 cases of intracranial epidermoids were treated by combined microscopic and endoscopic techniques. Initially, the tumor was removed under the microscope and after ensuring maximum excision, the endoscope was used to find out and excise any residual tumor.

Results

Out of these 48 cases complete excision was achieved in 44 cases and subtotal excision in four patients. Postoperative complications were seen in 17 patients, but none of the complications was attributed to the use of endoscope. Overall use of endoscope benefited 79% of cases.

Conclusion

We recommend combined microsurgical and endoscopic approach to achieve complete/maximum resection of extensive intracranial epidermoid tumors.

Fully Endoscopic Retrosigmoid Vestibular Nerve Section for Refractory Meniere Disease

OBJECTIVE

This study aims to report our results and technical details of fully endoscopic retrosigmoid vestibular nerve section.

DESIGN

A prospective observational study was conducted.

SETTING

A single academic, tertiary institution involving neurosurgery and neurotology.

PARTICIPANTS

Previously diagnosed patients with Meniere disease, refractory to medical therapy, who underwent fully endoscopic vestibular nerve section.

MAIN OUTCOME MEASURES

Postoperative improvement in vertiginous symptoms as well as hearing preservation, based on the American Association of Otolaryngology-Head and Neck Surgeons score and the Gardener and Robertson-Modified Hearing Classification. Facial nerve preservation based on the House-Brackman (HB) score.

RESULTS

Symptoms improved or resolved in 38 of 41 (92.2%) patients with only 1 of 41 (2.4%) reporting worsening symptoms. All 41 patients (100%) had a postoperative HB score of 1/6, demonstrating full facial nerve preservation. Hearing was stable or improved in 34 of 41 (82.9%) patients. Three complications took place for a rate of 7.3%, one cerebrospinal fluid leak, and two wound infections.

CONCLUSION

The fully endoscopic approach to vestibular nerve sections is a safe and effective technique for the treatment of medically refractory Meniere disease. This technique also utilizes smaller incisions, minimal cranial openings, and no cerebellar retraction with improved visualization of the cerebellopontine angle neurovascular structures.

The combined microscopic-endoscopic technique for radical resection of cerebellopontine angle tumors

OBJECT

The combined microscopic and endoscopic technique has shown significant advantages in the management of various lesions through different approaches. Endoscopic-assisted techniques have frequently been applied to cerebellopontine angle (CPA) surgery in the context of minimally invasive craniotomies. In this paper the authors report on the use of the endoscope in the CPA as a tool to increase the extent of resection, minimize complications, and preserve the function of the delicate CPA structures. They also describe a technique of the simultaneous use of the microscope and endoscope in the CPA and dissection of CPA tumors under tandem endoscopic and microscopic vision to overcome the shortcomings of introducing the endoscope alone in the CPA. The reliability of using the microscope alone in dissecting CPA tumors is evaluated, as is the effectiveness of the combined technique in increasing the resectability of various types of CPA tumors.

METHODS

The authors conducted a retrospective analysis of 50 patients who underwent combined microscopic-endoscopic resection of CPA tumors by the senior author over a period of 3 years (February 2011 to February 2014) at Brigham and Women's Hospital, Harvard Medical School. The reliability of the extent of microscopic removal was evaluated with endoscopic exploration. Additional resection was performed with both microscopic and the combined microscopic-endoscopic technique. Endoscopically verified total resection was validated by intraoperative or postoperative MRI. The function of the cranial nerves was evaluated to assess the impact of the combined technique on their function.

RESULTS

A tumor remnant was endoscopically identified in 69% of the 26 patients who were believed to have microscopic total resection. The utilization of the endoscopic visualization and dissection increased endoscopically verified total removal to 38 patients, and 82% of these patients had no sign of residual tumor on postoperative imaging. The technique was most effective with epidermoid tumors. There were a total of 17 new cranial nerve deficits in 10 patients. Preoperative fifth cranial nerve deficits improved in 52% and hearing improved in 29% of patients after surgery.

CONCLUSIONS

This method provides simultaneous microscopic and endoscopic visualization and dissection techniques through skull-base approaches to CPA tumors. It overcomes some of the shortcomings of endoscopic-assisted surgery, further extends the surgical field, and increases the radicality of tumor resection with good functional outcomes.

Endoscopic Resection of Vestibular Schwannomas

Objective To report our results and the technical details of fully endoscopic resection of vestibular schwannomas. Design Prospective observational study. Setting A single academic institution involving neurosurgery and neurotology. Participants Twelve consecutive patients who underwent fully endoscopic resection of a vestibular schwannoma. Main Outcome Measures Hearing preservation, based on the American Association of Otolaryngology-Head and Neck Surgeons (AAO-HNS) score as well as the Gardener and Robertson Modified Hearing Classification (GR). Facial nerve preservation based on the House-Brackmann (HB) score. Results All patients successfully underwent gross total resection. Facial nerve preservation rate was 92% with 11 of 12 patients retaining an HB score of 1/6 postoperatively. Hearing preservation rate was 67% with 8 of 12 patients maintaining a stable AAO-HNS grade and GR score at follow-up. Mean tumor size was 1.5 cm (range: 1-2 cm). No patients experienced postoperative cerebrospinal fluid leak, infection, or cranial nerve palsy for a complication rate of 0%. Mean operative time was 261.6 minutes with an estimated blood loss of 56.3 mL and average length of hospital stay of 3.6 days. Conclusion A purely endoscopic approach is a safe and effective option for hearing preservation surgery for vestibular schwannomas in appropriately selected patients.

Surgical strategy for intracranial dermoid and epidermoid tumors: An experience with 33 Patients

Background:

The aim of this paper is to report on our surgical strategy and technique and to identify the best management for intracranial dermoids and epidermoids tumors (IDETs).

Methods:

We retrospectively reviewed 33 consecutive patients (14 males and 19 females; mean age at surgery, 37.9 years) with pathologically confirmed IDETs who underwent surgical resection, with mean follow-up of 7.2 years.

Results:

Gross total tumor removal was achieved in 24 cases (72.7%) with zero surgical mortality and a recurrence rate of 9%.

Conclusions:

The surgical strategies used in this group of patients enabled total removal of most tumors without surgical mortality and with low morbidity and recurrence rates, proving to be safe and effective.

Pure endoscopic removal of epidermoid tumors of the cerebellopontine angle

PURPOSE

Epidermoid tumors located in the cerebellopontine angle (CPA) are challenging lesions because they tend to grow slowly in the subarachnoid cisterns around delicate neurovascular structures and often extend into surgical anatomic corners. The aim of this paper is to demonstrate the advantages and limitations of purely endoscopic removal of the CPA epidermoids.

METHODS

Six patients harboring an epidermoid tumor located in the CPA were treated using an endoscope-controlled microsurgical technique. A retrosigmoid suboccipital approach was used in all patients. The cerebellomedullary cistern and the cisterna magna were opened to allow cerebrospinal fluid drainage and cerebellar drop, thus yielding a wide and straight working channel to the CPA. Then, the tumor and its capsule were removed by the modified microsurgical instruments.

RESULT

The symptoms caused by mass effect of the lesion resolved after surgery. There were no deaths, but permanent deficits occurred in one patient whose cranial nerves VII/VIII complex was accidentally lesioned. Tumors and their capsules were totally removed in five cases. All patients were discharged 3-5 days after surgery. To date, no recurrences have been observed (follow-up range 14-50 months).

CONCLUSION

The endoscope-controlled microsurgical technique enables a safe tumor removal even when parts of the lesion are not visible in a straight line in CPA epidermoids. By angled endoscopic lenses, tumor extending into adjacent cranial compartments or surgical anatomic corners can be removed through a single small craniotomy without retracting neurovascular structures.

An endoscopic-assisted technique for retrosellar access during the extended retrosigmoid approach: a cadaveric feasibility study and quantitative analysis of retrosellar working area

The retrosigmoid approach has been advocated for certain petroclival tumors but provides limited access to any retrosellar extension of tumor, necessitating a two-stage operation. Our purpose was to demonstrate preliminary feasibility of an endoscopic-assisted technique to provide retrosellar access during the extended retrosigmoid approach and compare microscopic and endoscopic retrosellar working area. Standard retrosigmoid craniectomy and partial petrosectomy respecting inner ear structures were performed on six embalmed cadaveric heads. Two balloons were inflated to simulate a 15 mm petroclival tumor. Retrosellar clival and brainstem working area and ipsilateral oculomotor nerve and posterior cerebral artery (PCA) working distance were measured using the endoscope and microscope. Artificial tumors were implanted and resected using the endoscopic-assisted technique to assess feasibility. The endoscope provided significantly greater mean working area/distance on the clivus (201.6 vs 114.8 mm(2), p < 0.01), brainstem (223.5 vs 121.2 mm(2), p < 0.01), ipsilateral oculomotor nerve (10.8 vs 6.4 mm, p < 0.01), and ipsilateral PCA (13.7 vs 8.9 mm, p = 0.01). Petrous dissection to create a 10 × 10 mm working channel and artificial tumor resection was feasible in all dissections. The superior petrosal vein required ligation in 9 (75%) cases. Air cells were exposed in 1 (8%) case. The described endoscopic-assisted technique can provide retrosellar access during the extended retrosigmoid approach to access petroclival tumors with retrosellar extension. Risks include superior petrosal vein sacrifice, bleeding that can impair visualization, injury to the trigeminal nerve during endoscopic insertion/manipulation or injury to the brainstem while working in the medial limits of exposure. Further work is necessary to determine clinical feasibility, safety, and efficacy.

Vestibular schwannoma surgical treatment

Neurosurgical intervention remains the main step in the effective management of vestibular schwannomas. Extensive studies on vestibular schwannoma treatment have placed emphasis on preserving quality of life and neurological functions, particularly of the facial and vestibulocochlear nerves. Facial nerve preservation and hearing preservation have been achieved by significant advances in skull base microsurgical techniques and intraoperative neuromonitoring. Diffusion tensor imaging is a powerful and accurate method for preoperatively identifying the facial nerve in relation to vestibular schwannomas. Endoscopy offers excellent illumination of the anatomical structures and provides panoramic vision inside the surgical area. In this report, we focused on facial nerve and vestibulocochlear nerve preservation and analyzed the major techniques used for identifying the nerve-tumor relationship.

[Neurosurgical importance of the superior petrosal venous complex]

OBJECTIVE

To study the microsurgical anatomy of the superior petrosal venous complex (SPVC).

MATERIAL AND METHODS

We conducted a descriptive and prospective study. Six injected specimens were used (12 sides). The microsurgical anatomy of the SPVC was studied by means of an anterior, retrosigmoid and transpetrosal approach. Neurosurgical equipment, 0-degree rigid endoscopy and OPMI-1 surgical microscope with 6× to 20× magnification were all used in this study. The venous drainage pattern toward the superior petrosal sinus was analysed, as were the formation of tributary veins, the relationship with the trigeminal nerve and the anatomical variants of SPVC.

RESULTS

The SPVC was present in all cases. A tributary, cerebellopontine fissure vein was identified in 100% of cases. The venous drainage pattern of the SPVC was divided into medial, intermediate and lateral with respect to the suprameatal crest. The SPVC was simple in 8 sides and duplicate in 4 sides. A triangle formed by the tentorium, the SPVC and part of the tentorial and petrosal surface of the cerebellum was also observed in the study. This triangle was called the petrosal-tentorial triangle.

CONCLUSIONS

It is important to understand the microsurgical anatomy of the SPVC. Therefore, we propose the petrosal-tentorial triangle as a neurosurgical route for the management of pathologies from the cerebellopontine angle to the superior petroclival region.

Combined microsurgical and endoscopic removal of extensive suprasellar and prepontine epidermoid tumors

Epidermoids tend to grow around and adhere to critical neurovascular structures, but total or maximal tumor removal is recommended to reduce the risk of recurrence. We describe our method of combined microscopic and endoscopic resection for extensive epidermoid tumors. Thirteen patients with epidermoid tumors located in the suprasellar, prepontine, or surrounding cisterns underwent microsurgical resection with a rigid endoscope and a high definition camera system. An anterior petrosal and/or a pterional approach was selected in 6 patients and a lateral suboccipital approach in 7 patients. An endoscope was used with the operating microscope to remove 6 tumors through the anterior petrosal and/or pterional approaches in 5 cases and the lateral suboccipital approach in 1 case. An endoscope was used to confirm microscopic removal in 5 patients. Total removal was achieved in 5 patients and subtotal removal in 8 patients. We recommend the combined microsurgical and endoscopic approaches to achieve maximal resection of extensive suprasellar and prepontine epidermoids.

Endoscope-assisted microsurgical resection of skull base meningiomas

This study aims to determine the value of endoscope assistance in the microsurgical resection of skull base meningiomas. Fourty-six patients harboring a skull base meningioma underwent an endoscope-assisted microsurgical resection. In 30 patients (65%), tumor parts which could not be visualized under the microscope were detected with the endoscope. In 26 patients (56%), these tumor remnants were removed under endoscopic view. Gross total resection was achieved in 35 patients (76%) and near-total resection in 11 (24%). There was no surgical mortality. The major complication was new cranial nerve deficit. The application of endoscopes was most useful in the small supraorbital craniotomies to look under the ipsilateral optic nerve and internal carotid artery as well as to visualize the diaphragm sellae and olfactory groove. In the retrosigmoid craniotomies, the endoscope was beneficial to inspect the internal auditory canal, to look into Meckel's cave, or to inspect areas hidden behind the jugular tubercle and tentorial edge. There was no obvious complication related to the application of the endoscope. Endoscope assistance is particularly of value when skull base meningiomas are to be removed via small craniotomies to inspect blind corners which cannot be visualized in a straight line with the microscope. In addition, there is a benefit of using endoscopes with various angles of view in standard craniotomies and skull base approaches to look around bony and dural corners or to look behind neurovascular structures, by which the amount of skull base drilling and retraction to expose the tumor can be reduced.

Endoscopic minimally invasive neurosurgery: emerging techniques and expanding role through an extensive review of the literature and our own experience - part II: extraendoscopic neurosurgery

BACKGROUND/AIMS

The field of minimally invasive neurosurgery has grown dramatically especially in the last decades. This has been possible, in the most part, due to the advancements in technology especially in tools such as the endoscope. The contemporary classification scheme for endoscopic procedures needs to advance as well.

METHODS

The present classification scheme for neuroendoscopic procedures has become confusing because it mainly describes the use of the endoscope as an assisting device to the microscope. The authors propose an update to the current classification that reflects the independence of the endoscope as a tool in minimally invasive neurosurgery.

RESULTS

The proposed classification groups the procedures as 'intraendoscopic' neurosurgery or 'extraendoscopic' neurosurgery (XEN) in relation to the 'axis' of the endoscope. A review of the literature for the XEN group together with exemplary cases is presented.

CONCLUSION

We presented our proposed classification for the endoscope-only surgical procedures. The XEN group is expanded in this article.