Endoscopic Resection of Clival Malignancies

Skull Base Chordoma and Chondrosarcoma: Neuroradiologist's Guide to Diagnosis, Surgical Management, and Proton Beam Therapy

Skull base chordomas and chondrosarcomas are distinct types of rare, locally aggressive mesenchymal tumors that share key principles of imaging investigation and multidisciplinary care. Maximal safe surgical resection is the treatment choice for each, often via an expanded endoscopic endonasal approach, with or without multilayer skull base repair. Postoperative adjuvant radiation therapy is frequently administered, usually with particle therapy such as proton beam therapy (PBT). Compared with photon therapy, PBT enables dose escalation while limiting damage to dose-limiting neurologic structures, particularly the brainstem and optic apparatus, due to energy deposition being delivered at a high maximum with a rapid decrease at the end of the penetration range (Bragg peak phenomenon). Essential requirements for PBT following gross total or maximal safe resection are tissue diagnosis, minimal residual tumor after resection, and adequate clearance from PBT dose-limiting structures. The radiologist should understand surgical approaches and surgical techniques, including multilayer skull base repair, and be aware of evolution of postsurgical imaging appearances over time. Accurate radiologic review of all relevant preoperative imaging examinations and of intraoperative and postoperative MRI examinations plays a key role in management. The radiology report should reflect what the skull base surgeon and radiation oncologist need to know, including distance between the tumor and PBT dose-limiting structures, tumor sites that may be difficult to access via the endoscopic endonasal route, the relationship between intradural tumor and neurovascular structures, and tumor sites with implications for postresection stability. ©RSNA, 2024 Supplemental material is available for this article.

Endoscopy-assisted high cervical anterolateral retropharyngeal approach to clivus: a cadaveric study

Introduction

The surgical management of pathologies involving the clivus and craniocervical junction has always been considered a complex procedure because of the deeply located surgical targets and the surrounding complex neural and vascular anatomical structures. The most commonly used approaches to reach this area are the transnasal, transoral, and transcervical approaches.

Material and Methods

This approach was performed unilaterally on five cadaver heads and bilaterally on one cadaver head.

Results

We described a modified endoscope-assisted high cervical anterolateral retropharyngeal approach in which each stage of the procedure was demonstrated on human cadavers in a step-by-step manner using endoscopic camera views. This approach was broken down into nine steps. The neurovascular structures encountered at each step and their relationships with each other are demonstrated.

Discussion

The advantages and disadvantages of our modified approach were compared to the conventional transcervical, transoral, and endoscopic endonasal approaches.

Skull-Base Chondrosarcoma: A Systematic Review of the Role of Postoperative Radiotherapy

Surgery and radiotherapy are key elements to the treatment of skull-base chondrosarcomas; however, there is currently no consensus regarding whether or not adjuvant radiotherapy has to be administered. This study searched the EMBASE, Cochrane, and PubMed databases for clinical studies evaluating the long-term prognosis of surgery with or without adjuvant radiotherapy. After reviewing the search results, a total of 22 articles were selected for this review. A total of 1388 patients were included in this cohort, of which 186 received surgery only. With mean follow-up periods ranging from 39.1 to 86 months, surgical treatment provided progression-free survival (PFS) rates ranging from 83.7 to 92.9% at 3 years, 60.0 to 92.9% at 5 years, and 58.2 to 64.0% at 10 years. Postoperative radiotherapy provides PFS rates ranging between 87 and 96.2% at 3 years, 57.1 and 100% at 5 years, and 67 and 100% at 10 years. Recurrence rates varied from 5.3% to 39.0% in the surgery-only approach and between 1.5% and 42.90% for the postoperative radiotherapy group. When considering prognostic variables, higher age, brainstem/optic apparatus compression, and larger tumor volume prior to radiotherapy were found to be significant factors for local recurrence.

Skull Base Reconstruction by Subsite after Sinonasal Malignancy Resection

Reconstruction after the resection of sinonasal malignancies is complex and primarily dependent on the defect size and location. While the reconstructive paradigm for sellar mass resection is well delineated, the challenges associated with reconstruction after sinonasal malignancy resection are less well described. This narrative review will address the goals of reconstruction after both endonasal endoscopic and open sinonasal malignancy resection and reconstructive options specific to these subsites. The goals of reconstruction include repairing cerebrospinal fluid leaks, restoring sinonasal function, providing a nasal airway, and optimizing the patient's quality of life. These goals are often complicated by the anatomic nuances of each involved sinus. In this review, we will discuss the methods of reconstruction specific to each sinonasal subsite and describe the factors that guide choosing the optimal reconstructive technique.

Endoscopic Endonasal Surgery for Uncommon Pathologies of the Sellar and Parasellar Regions

Endoscopic skull base surgery has become an integral part of the present neurosurgical armamentarium. The pioneering efforts in which the purely endoscopic transsphenoidal approach was introduced have triggered a growing tide of using the endoscopic endonasal procedures for a large variety of skull base lesions. Because of their anatomical peculiarities, lesions of the sellar and parasellar regions lend themselves very well to the endoscopic endonasal approaches. Apart from the common pathological entities, many other less frequent pathologies are encountered in the sellar and parasellar area. In this chapter, we review the surgical technique of the endoscopic endonasal transsphenoidal approach and its extensions applied to a variety of rare and uncommon pathological entities involving the sella turcica and clivus. An overview of these pathological entities is also presented and exemplified.

Transfacial Exposures of the Anterior Skull Base and Cervical Spine: Straightforward "Line-of-Sight" Algorithm for Selection of Approach

ABSTRACT

Surgical treatment for tumors of the skull base remains gross total resection with microscopic negative margins. Sufficient surgical access is paramount to adequate treatment but must be balanced with patient morbidity and protection of vital neurovascular structures. While endoscopic surgery has made transfacial access less common, there are still indications for open transfacial exposure including tumors that involve facial soft tissues, the palate, anterolateral frontal sinus, dural involvement lateral to the mid-pupillary line, tumor recurrence/repeat resection, and/or lack of access to endoscopic equipment or expertise. The authors present a "line-of-sight" algorithm for selection of approach, discuss pre-operative planning, review selected clinical experiences, and discuss the role of microsurgery and prevention of complications.

Use of Ultrasound for Navigating the Internal Carotid Artery in Revision Endoscopic Endonasal Skull Base Surgery

While the use of image-guided navigation is an excellent adjunct to the use of anatomical landmarks, dynamic changes that may occur in the position of critical structures are not accounted for during and after tumor resection. Unlike navigation, Doppler ultrasonography provides real-time imaging of the anterior skull base and can be used to accurately identify the location of vital structures during skull base surgery.

A 56-year-old female initially presented with new onset left eye visual deficits. She previously underwent sublabial transsphenoidal subtotal resection of the tumor, confirmed as clival chordoma. She subsequently presented to our institution. She was treated with an expanded endonasal resection of the remaining chordoma followed by CyberKnife radiosurgery. Two years later, surveillance imaging identified tumor recurrence within the right clivus posterior to the carotid artery. Intraoperatively, in the previously operated irradiated skull base, the normal bony architecture of the sella was absent, resulting in the inability to distinguish the anterior genu of the internal carotid artery (ICA) from the adjacent tumor. Using Doppler ultrasonography, the course of the ICA was imaged in real time, allowing for safe, gross total tumor resection.

In the setting of prior operation, radiation, or extensive disease, the normal bony architecture of the sella may be disrupted, placing the cavernous ICA at risk. We report what we believe is the first use of intraoperative ultrasound during the endoscopic endonasal approach in the setting of a previously operated, radiated sella.

[Multidisciplinary management of clival chordoma]

Chordoma of the clivus belong to the rare tumors of the skull base. Due to their aggresive behaviour including intradural infiltration of neurovascular structures an interdisciplinary treatment is mandatory. This article gives an overview on current surgical concepts including the endoscopic approach as well as the postoperative radiotherapy. Novel diagnostic tools and molecular targets to optimize individual tumor therapy are discussed.

Clival simple bone cyst: Rare pathological entity (case report)

Background:

Clival cystic lesions are not frequently seen in neurosurgery. Cystic lesion in the clivus can be part of a neoplastic process such as chordoma, chondrosarcoma, plasmacytoma, or metastasis. Rare types of pure cystic clival lesions include simple bone cysts and arachnoid cysts, which are asymptomatic most of the time and do not cause symptoms until they reach a large size.

Case Description:

This is a case report of a healthy 53-year-old male patient with a clival cystic lesion. The patient underwent surgical drainage and wall resection of the clival lesion with no postoperative complications. Intraoperative finding raised the possibility of the diagnosis of an arachnoid cyst. However, the pathology findings indicated a simple bone cyst.

Conclusion:

Simple bone cyst and arachnoid cyst in the clivus are rare, they should be considered in the diagnosis of clival cystic lesions.

ICAR: endoscopic skull-base surgery

BACKGROUND

Endoscopic skull-base surgery (ESBS) is employed in the management of diverse skull-base pathologies. Paralleling the increased utilization of ESBS, the literature in this field has expanded rapidly. However, the rarity of these diseases, the inherent challenges of surgical studies, and the continued learning curve in ESBS have resulted in significant variability in the quality of the literature. To consolidate and critically appraise the available literature, experts in skull-base surgery have produced the International Consensus Statement on Endoscopic Skull-Base Surgery (ICAR:ESBS).

METHODS

Using previously described methodology, topics spanning the breadth of ESBS were identified and assigned a literature review, evidence-based review or evidence-based review with recommendations format. Subsequently, each topic was written and then reviewed by skull-base surgeons in both neurosurgery and otolaryngology. Following this iterative review process, the ICAR:ESBS document was synthesized and reviewed by all authors for consensus.

RESULTS

The ICAR:ESBS document addresses the role of ESBS in primary cerebrospinal fluid (CSF) rhinorrhea, intradural tumors, benign skull-base and orbital pathology, sinonasal malignancies, and clival lesions. Additionally, specific challenges in ESBS including endoscopic reconstruction and complication management were evaluated.

CONCLUSION

A critical review of the literature in ESBS demonstrates at least the equivalency of ESBS with alternative approaches in pathologies such as CSF rhinorrhea and pituitary adenoma as well as improved reconstructive techniques in reducing CSF leaks. Evidence-based recommendations are limited in other pathologies and these significant knowledge gaps call upon the skull-base community to embrace these opportunities and collaboratively address these shortcomings.

Metastatic Disease to Clivus: Biopsy or Not?

Due to the aggressive nature of hepatocellular carcinoma (HCC), most patients succumb to disease before any distant metastasis, such as to the central nervous system (CNS), can occur. Thus only a handful of cases of metastasis to the skull base have been described. After a thorough review of the available literature published since 1950, we report the sixth case of HCC metastasis to the clivus. In this case, a 65-year-old man with a history of melanoma presented with sudden onset of right-sided headache and complete ophthalmoplegia of the right eye for one month. MRI of the brain with and without contrast demonstrated a homogeneously enhancing lesion involving the clivus with evidence of invasion into the right cavernous sinus. Through further body imaging, he was found to have an infiltrative lesion in the left hepatic lobe and underwent an ultrasound-guided biopsy of said lesion that was proven to be well-differentiated hepatocellular carcinoma. An endonasal endoscopic biopsy of his clival lesion was performed and the final pathology was consistent with a metastatic HCC. This case demonstrates the impact of obtaining a surgical specimen of clival tumors to confirm the suspected diagnosis, as well as to perform molecular studies that can drive post-operative decision-making and prognosis. As in this case, the final diagnosis altered treatment plans from that of melanoma, with systemic chemotherapy and radiosurgery, to stereotactic radiosurgery and intrahepatic radioembolization.

The Differences Between Intracranial Mesenchymal Chondrosarcoma and Conventional Chondrosarcoma in Clinical Features and Outcomes

OBJECTIVE

To report differences in clinical features and outcomes between intracranial mesenchymal chondrosarcoma (MCS) and conventional chondrosarcoma (CCS).

METHODS

Clinical data of patients with primary intracranial MCS and CCS were retrospectively extracted and analyzed to compare differences between MCS and CCS.

RESULTS

Seventy-four patients with intracranial chondrosarcoma (61 cases with MCS and 13 cases with CCS) were included. Compared with patients with CCS, patients with MCS presented at a younger mean age (21.1 years vs. 34.5 years, P < 0.001) and had a poor mean preoperative Karnofsky performance scale score (64.6 vs. 77.8, P = 0.014). Compared with CCS, MCS was less often located in the skull base (38.5% vs. 96.7%, P < 0.001) and had a larger tumor volume (87.8 cm³ vs. 26.7 cm³, P < 0.001). Rates of gross total resection in MCS and CCS subgroups were 41.1% (n = 25) and 46.2% (n = 6), respectively; rates of adjuvant radiotherapy postoperatively were 44.2% (n = 27) and 46.2% (n = 6), respectively. After mean follow-up of 41.7 months, 1-year, 3-year, and 5-year overall survival and progression-free survival of MCS were significantly shorter than overall survival and progression-free survival of CCS. Multivariate analysis revealed that tumor pathology and extent of surgery were independent predictors for tumor recurrence.

CONCLUSIONS

Clinical features of MCS are quite different from CCS. Treatment strategies used for CCS do not yield satisfactory outcomes for MCS. Treatment of MCS should be aggressive and individualized.

An Innovate Robotic Endoscope Guidance System for Transnasal Sinus and Skull Base Surgery: Proof of Concept

Objective  Advanced transnasal sinus and skull base surgery remains a challenging discipline for head and neck surgeons. Restricted access and space for instrumentation can impede advanced interventions. Thus, we present the combination of an innovative robotic endoscope guidance system and a specific endoscope with adjustable viewing angle to facilitate transnasal surgery in a human cadaver model. Materials and Methods  The applicability of the robotic endoscope guidance system with custom foot pedal controller was tested for advanced transnasal surgery on a fresh frozen human cadaver head. Visualization was enabled using a commercially available endoscope with adjustable viewing angle (15-90 degrees). Results  Visualization and instrumentation of all paranasal sinuses, including the anterior and middle skull base, were feasible with the presented setup. Controlling the robotic endoscope guidance system was effectively precise, and the adjustable endoscope lens extended the view in the surgical field without the common change of fixed viewing angle endoscopes. Conclusion  The combination of a robotic endoscope guidance system and an advanced endoscope with adjustable viewing angle enables bimanual surgery in transnasal interventions of the paranasal sinuses and the anterior skull base in a human cadaver model. The adjustable lens allows for the abandonment of fixed-angle endoscopes, saving time and resources, without reducing the quality of imaging.

Proposed Treatment Paradigm for Intracranial Chondrosarcomas Based on Multidisciplinary Coordination

OBJECTIVES

There was no consensus regarding the treatment of intracranial chondrosarcoma (CSA). The study aimed to evaluate the adverse factors for progression-free survival (PFS) and overall survival (OS) and to propose a treatment strategy for CSA.

METHODS

The clinical chart and radiographic data of 106 consecutive cases (mesenchymal and conventional CSA in 18 and 88 patients, respectively) of surgically treated CSAs were retrospectively reviewed.

RESULTS

Gross total resection was achieved in 43 patients (40.6%), and adjuvant radiotherapy was administered in 45 patients. After a mean follow-up duration of 47.8 months, 38 patients (37.3%) experienced recurrence. PFS and disease-specific OS at 5 years was 57.7% and 74.4%. Independent adverse factors for PFS were previous surgery (hazard ratio [HR] 2.261; P = 0.028), increased lesion size (HR, 1.298; P = 0.026), extent of surgical resection (HR, 3.226; P < 0.001), malignant pathology (HR, 2.018; P = 0.003), and postoperative radiotherapy (HR, 3.246; P = 0.001). The stereotactic radiosurgery subgroup presented best 5-year PFS of 88.9%, and a linear accelerator prolonged the mean PFS time (57.0 months) compared with no radiation (38.1 months). In the incomplete resection subgroup (n = 63), radiotherapy significantly benefited tumor control (HR, 2.101; P = 0.016). Extent of surgical resection (HR, 1.797; P = 0.026) and malignant disease (HR, 1.717; P = 0.030) were associated with OS.

CONCLUSIONS

Intracranial CSAs were not completely amendable by surgery alone. Gross total resection as far as possible plus radiation were necessary for mesenchymal CSA and conventional CSA with active growth or residual tumor. Stereotactic radiosurgery was an alternative if proton therapy was unavailable. A future study with a large cohort is required to verify our findings.

Insidious enemy: downside to prolonged survival in prostate cancer

An 83-year-old man, a prostate cancer survivor of 10 years with multiple vertebral metastases presented with sudden onset of double vision. On examination he was found to have an isolated partial left abducens palsy with no other neurological deficits. Despite having microvascular risk factors, given his history of prostate cancer, aMRI brain scan was requested to look for a neurological cause. The scan revealed a metastatic lesion in the clivus encasing the cavernous sinus and carotid artery. He was referred to his oncologist for further management, however he opted out of further treatment and succumbed to his illness a month later. This case report includes a literature review of cases with clivus metastases secondary to prostate cancer. It highlights the importance of carefully examining eye movements and having a high index of suspicion for the subtlest sign that may suggest brain metastases in elderly patients with prostate cancer with prolonged survival.