Combined transpetrosal-subtemporal craniotomy for clival tumors with extension into the posterior fossa

Transpetrosal Routes to the Skull Base-Anterior and Posterior Transpetrosal Approaches

The extended middle fossa approach with anterior petrosectomy, or anterior transpetrosal approach, is a highly effective and direct approach to difficult-to-access petroclival tumors and basilar artery aneurysms. This surgical approach exposes a significant window of the posterior fossa dura between the mandibular nerve, internal auditory canal, and petrous internal carotid artery, below the level of the petrous ridge, and provides an unobstructed view of the middle fossa floor to the upper half of the clivus and petrous apex, without requiring removal of the zygoma. The posterior transpetrosal approaches, including the perilabyrinthine, translabyrinthine, and transcochlear approaches, provide direct and wide exposure of the cerebellopontine angle and posterior petroclival region. The translabyrinthine approach is commonly used for the removal of acoustic neuromas and other lesions of the cerebellopontine angle. We provide a stepwise description of how we perform these approaches and how to combine and extend them in order to achieve transtentorial exposure.

Endoscopic endonasal and transorbital approaches to petrous apex lesions

OBJECTIVE

The petrous apex (PA) is one of the most challenging areas in skull base surgery because it is surrounded by numerous critical neurovascular structures. The authors analyzed the clinical outcomes of patients who underwent endoscopic endonasal approach (EEA) and transorbital approach (TOA) procedures for lesions involving PA to determine the perspectives and proper applications of these two approaches.

METHODS

The authors included patients younger than 80 years with lesions involving PA who were treated between May 2015 and December 2019 and had regular follow-up MR images available for analysis. Patients with meningioma involving petroclival regions were excluded. The authors classified PA into three regions: superior to the petrous segment of the internal carotid artery (p-ICA) (zone 1); posterior to p-ICA (zone 2); and inferior to p-ICA (zone 3). Demographic data, preoperative clinical and radiological findings, surgical outcomes, and morbidities were reviewed.

RESULTS

A total of 19 patients with lesions involving PA were included. Ten patients had malignant tumor (chondrosarcoma, chordoma, and osteosarcoma), and 6 had benign tumor (schwannoma, Cushing's disease, teratoma, etc.). Three patients had PA cephalocele (PAC). Thirteen patients underwent EEA, and 5 underwent TOA. Simultaneous combined EEA and TOA was performed on 1 patient. Thirteen of 16 patients (81.3%) had gross- or near-total resection. Tumors within PA were completely resected from 13 of 16 patients using a view limited to only the PA. Complete obliteration of PAC was achieved in all patients. Postoperative complications included 2 cases of CSF leak, 1 case of injury to ICA, 1 fatality due to sudden herniation of the brainstem, and 1 case of postoperative diplopia.

CONCLUSIONS

EEA is a versatile surgical approach for lesions involving all three zones of PA. Clival tumor spreading to PA in a medial-to-lateral direction is a good indication for EEA. TOA provided a direct surgical corridor to the superior portion of PA (zone 1). Patients with disease with cystic nature are good candidates for TOA. TOA may be a reasonable alternative surgical treatment for select pathologies involving PA.

The Transpetrosal-Ridge Approach: A Modification of the Combined Transpetrosal Approach

Background

Petroclival tumors are formidable challenges for skull base surgeons. Obtaining adequate surgical access is a paramount consideration. Although the combined transpetrosal approach provides a wide surgical corridor, it is technically challenging and, to a degree, morbid. This article describes the transpetrosal-ridge approach, which is a modification of the combined transpetrosal approach with improvements with regards to ease of execution and reduced surgical morbidity.

Methods

The key elements of the transpetrosal-ridge approach are outlined, followed by a detailed description of the steps. The head is placed in the lateral position. After skin incision and muscle elevation, a temporo-suboccipital craniotomy is performed. Middle fossa dura is elevated to the petrous ridge. A limited mastoidectomy is performed with preservation of the semicircular canals. The remaining petrous ridge is then resected and the posterior fossa dura is opened, with the opening extending through the trigeminal dural ring.

Results

Steps of the combined transpetrosal approach that do not contribute to the final surgical corridor are omitted. Extensive mastoid and petrous apex resection is avoided. Posterior fossa dural opening extending through the trigeminal dural ring is a critical step, as it detaches the superior petrosal sinus and sigmoid sinus from the petrous bone. With the retraction of the temporal lobe and the cerebellum and sigmoid sinus, a wide surgical corridor is obtained.

Conclusions

The transpetrosal-ridge approach is a modification of the combined transpetrosal approach with optimization of the operative steps while continuing to provide a wide surgical corridor to the petroclival region.

Comprehensive review of the extended middle cranial fossa approach

PURPOSE OF REVIEW

To review the current literature on the extended middle cranial fossa (xMCF) approach and to provide a comprehensive description of the relevant anatomy, indications, surgical technique, results, and complications.

RECENT FINDINGS

The xMCF approach expands the surgical exposure provided by the sMCF approach, allowing access to the internal auditory canal, cerebellopontine angle, prepontine cistern, anterior petrous apex, petrous carotid artery, Meckel's cave, cavernous sinus, mid and upper clivus, and posterior lesions approaching the jugular foramen. Preservation of serviceable hearing is possible with success rates approximating 50% in vestibular schwannoma and meningioma resection, and facial nerve outcome is excellent.

SUMMARY

The xMCF is an important approach for difficult to access lesions that additionally offers the possibility of hearing preservation. This approach is also useful for vascular lesions, auditory brainstem implantation, and lesions of mid-brainstem.

Treatment of Lateral Skull Base and Posterior Cranial Fossa Lesions Utilizing the Extended Middle Cranial Fossa Approach

OBJECTIVE

Define the indications and outcomes for subjects undergoing treatment utilizing the extended middle cranial fossa approach (EMCF).

STUDY DESIGN

Retrospective records review.

SETTING

University-based tertiary referral center.

PATIENTS

Subjects undergoing treatment of posterior cranial fossa (PCF) lesions.

INTERVENTION(S)

EMCF exposure and treatment of the indicating PCF lesion.

MAIN OUTCOME MEASURE(S)

Demographic, audiometric, and cranial nerve functioning variables were assessed.

RESULTS

Thirty-five subjects who underwent an EMCF exposure were identified over a 12-year period. The most common indication was meningioma (18; 51%) followed by schwannomas (six, 17%), and vascular lesions (five, 14%). Preoperative cranial nerve complaints were common (32, 94%) as were objective cranial nerve abnormalities on physical examination (21; 60%). Preoperative audiometric data from subjects with hearing demonstrated good functioning including pure-tone average (PTA) (21.7 ± 15.6 dB HL) and word understanding scores (95.1 ± 7.4%). Most (34, 97%) subjects had intact facial nerve function. The average length of stay was 11.6 days (median = 9). Cranial neuropathies were common postoperatively with 27 (79%) subjects demonstrating some objective cranial nerve dysfunction, the most common of which was trigeminal nerve hypesthesia (21, 61.7%). Subjects with identifiable pre- and postoperative audiometric data and preoperative hearing demonstrated small declines in the four-tone average (16.2 dB) and word recognition scores (22.4%). Two subjects (6%) had new profound hearing loss postoperatively.

CONCLUSIONS

The EMCF approach can provide safe and effective exposure of the anterior PCF.

Skull base chondrosarcomas: surgical treatment and results

OBJECTIVES

We describe our experience in the management of patients with skull base chondrosarcoma, an uncommon neoplasm of the skull base.

METHODS

Thirteen cases of surgically treated skull base chondrosarcomas were identified. The patients' follow-ups ranged from 7 to 86 months (mean, 47 months).

RESULTS

The most common tumor locations were the jugular foramen (5 cases), the petrous apex (3 cases), and the petroclival region (3 cases). An infratemporal fossa type A approach was performed in 2 cases, and 2 patients underwent an infratemporal fossa type B approach. Two patients underwent a transotic approach, 1 patient underwent a petro-occipital transsigmoid approach, and a petro-occipital transsigmoid approach combined with a transotic approach was chosen in 1 case. One patient underwent an infratemporal fossa type C approach combined with a transotic approach, and 2 patients underwent an infratemporal fossa type B approach combined with a transotic approach. One patient underwent an infratemporal fossa type B approach combined with a transzygomatic approach, and the last patient underwent a transmastoid approach. Gross total tumor removal was achieved in all patients. Postoperative radiotherapy was performed in 7 cases. The most common complications were lower cranial nerve deficits. Two patients experienced recurrences, 36 months and 6 years after surgical removal.

CONCLUSIONS

We believe that the primary treatment for chondrosarcomas of the skull base is gross total surgical resection. We usually do not recommend radiotherapy as the primary treatment for patients with skull base chondrosarcomas; however, radiotherapy may be considered as an alternative primary treatment in selected cases in which there are serious medical contraindications to surgery, as well as in elderly patients. We reserve postoperative radiotherapy for patients with histologically aggressive tumors (grade II or III), as well as for cases of subtotal resection or recurrent tumors.

Endoscopic skull base surgery: a comprehensive comparison with open transcranial approaches

Little data exists comparing endoscopic endonasal approaches to pathology of the anterior skull base with more traditional transcranial and transsphenoidal microscopic approaches. In order to more fully characterize the role of endoscopy in the management of pathology of the anterior cranial base, we conducted a systematic review of case series and case reports documenting surgical and clinical outcomes. We found that for craniopharyngiomas, clival chordomas, esthesioneuroblastomas and giant pituitary adenomas, the endonasal endoscopic approach can result in equivalent or higher rates of gross total resection than open approaches. For meningiomas, however, open transcranial approaches are still able to achieve higher rates of total resection. CSF leak rates are higher for patients undergoing endoscopic surgery for meningiomas and craniopharyngiomas, but not for chordomas, esthesioneuroblastomas or giant pituitary adenomas. In certain patients, the endonasal endoscopic approach may be a safe and effective alternative for the treatment of a wide variety of skull base pathology, particularly those with small midline tumours.

Cranial chondrosarcoma and recurrence

The literature regarding recurrences in patients with cranial chondrosarcoma is limited to small series performed at single institutions, raising the question if these data precisely reflect the true recurrence of this tumor for guiding the clinician in the management of these patients. An extensive systematic review of the English literature was performed. The patients were stratified according to treatment modality, treatment history, histological subtype, and histological grade, and the recurrence rates were analyzed. A total of 560 patients treated for cranial chondrosarcoma were included. Five-year recurrence rate among all patients was 22% with median follow-up of 60 months and median disease-free interval of 16 months. Tumor recurrence was more common in patients who only received surgery or had mesenchymal subtype tumors. Our systematic review closely reflects the actuarial recurrence rate and provides predictive factors in the recurrence of cranial chondrosarcoma.

A comprehensive analysis of intracranial chordoma and survival: a systematic review

OBJECTIVE

Despite the published information on cranial chordoma, most of the data regarding survival in these patients has come from a single institution. Here, we perform a systematic review of the literature to evaluate across multiple institutions the overall survival after treatment for intracranial chordoma.

MATERIALS AND METHODS

We systematically analysed every study published in English and found a total of over 2000 patients being treated for intracranial chordoma. The overall 5-year and 10-year survivals in these patients were stratified according to the age (<5 years vs. >5 years and  <40 years vs. >40 years), treatment (surgery and radiation vs. surgery alone) and histological findings (chondroid vs. typical). Data were analysed via Pearson chi-square test and student t-test when appropriate.

RESULTS

A total of 560 non-duplicated patients treated for cranial chordoma met inclusion criteria for this systematic analysis. The survival rate among these patients was 63% (299 patients) and 16% (176 patients) for 5-year and 10-year survivals, respectively. There was no difference in overall survival between the two groups when a cut-off age of 40 years was used (<40 years = 50% vs.  >40 years = 51% at 5-year survival; p = 0.1), but when 5 years was used as the cut-off age, then survival was better for patients in the group older than 5 years of age (<5 years = 14% vs.  >5 years = 66%; p = 0.001). There was no difference between 5-year survival in patients with chordoma with histological chondroid features and those with chordoma possessing typical histology (45% vs. 67%; p = 0.06). When patients who only received surgery were compared to those patients who were treated with surgical intervention in combination with adjuvant radiation treatment, no difference in survival rate was found (54% vs. 56% at 5 years; p = 0.8).

CONCLUSION

The results of our systematic study provide data to predict the survival of intracranial chordoma patients across multiple institutions. Our data suggest that patients younger than 5 years of age may be associated with a worse prognosis, and adjuvant radiation therapy and histological type were not associated with the improvement of survival rates.

Adjuvant radiation therapy and chondroid chordoma subtype are associated with a lower tumor recurrence rate of cranial chordoma

Cranial chordomas are rare tumors that have been difficult to study given their low prevalence. Individual case series with decades of data collection provide some insight into the pathobiology of this tumor and its responses to treatment. This meta-analysis is an attempt to aggregate the sum experiences and present a comprehensive review of their findings. We performed a comprehensive review of studies published in English language literature and found a total of over 2,000 patients treated for cranial chordoma. Patient information was then extracted from each paper and aggregated into a comprehensive database. The tumor recurrences in these patients were then stratified according to age (<21 vs. >21 years), histological findings (chondroid vs. typical) and treatment (surgery and radiation vs. surgery only). Data was analyzed via Pearson chi-square and t-test. A total of 464 non-duplicated patients from 121 articles treated for cranial chordoma met the inclusion criteria. The recurrence rate among all patients was 68% (314 patients) with an average disease-free interval of 45 months (median, 23 months). The mean follow-up time was 39 months (median, 27 months). The patients in younger group, patients with chordoma with chondroid histologic type, and patients who received surgery and adjuvant radiotherapy had significantly lower recurrence rate than their respective counterparts. The results of our systematic analysis provide useful data for practitioners in objectively summarizing the tumor recurrence in patients with cranial chordomas. Our data suggests that younger patients with chondroid type cranial chordoma treated with both surgery and radiation may have improved rates of tumor recurrence in the treatment of these tumors.

A systematic review of intracranial chondrosarcoma and survival

Most data regarding survival in patients with chondrosarcoma are limited to case studies and small series performed at single institutions. A systematic review was performed to study the relationship between potential prognostic factors and survival. The survival rates were analyzed according to modality of treatment, treatment history, histological subtype, and histological grade. A total of 560 patients with intracranial chondrosarcoma were analyzed. Median follow-up time was 60 months. The 5-year mortality among all patients was 11.5% with median survival of 24 months. Mortality at 5 years was significantly greater for patients with tumors of higher grade, or of the mesenchymal subtype, or who had received surgical resection alone. The results of our systematic review provide useful data in predicting survival among intracranial chondrosarcoma patients.

Surgery for clival lesions: open resection versus the expanded endoscopic endonasal approach

OBJECT

Clival lesions pose significant challenges with regard to their surgical management. The expanded endoscopic endonasal (EEE) approach is a promising minimally invasive technique for lesions of the central skull base. The authors' aim in the current paper was to discuss the surgical treatment of clival lesions and to present the technical details, indications, and limitations of the EEE approach. Data from a recent endoscopically treated group will be compared with findings in a previous cohort of patients treated via classic open anterior and lateral approaches.

METHODS

Since June 2005, 17 patients with clival lesions underwent surgery via the EEE approach. Suitable candidates were chosen according to lesion characteristics, clinical parameters, and surgical goals. Neurological outcomes, Karnofsky Performance Scale scores, the extent of lesion resection, and complications were evaluated among these patients. Eighteen percent of the patients in the endoscopic group presented with recurrent disease. Another series of 43 patients, who had undergone resection of clival lesions via an anterior (rhinotomy, maxillectomy, microscopic transsphenoidal surgery, or transoral surgery) or lateral (pterional, frontoorbitozygomatic, or combined suprainfratentorial retrosigmoid) approach, was similarly reviewed. Twenty-three of these patients (53%) presented with recurrent disease and thus had undergone prior surgery.

RESULTS

Following the EEE approach, 11 (79%) of 14 patients who had presented with neurological symptoms experienced improvement, and gross-total resection was achieved in 59% of the patients and subtotal removal in 41%. Complications included CSF leakage (24%), tension pneumocephalus (6%), and intracranial hematoma (6%). The patient with the latter complication was the only one who experienced permanent neurological worsening. In the open resection group, neurological worsening occurred in 33% of the patients (14 of 43). Total and grosstotal removals were achieved in 84% of patients and subtotal removal in 14%.

CONCLUSIONS

The EEE approach has been shown to be a safe and effective technique for the resection of clival lesions with limited lateral extension. The choice of surgical approach must be tailored according to both patient and tumor characteristics. Although the 2 patient series featured in this paper are not comparable-because of a selection bias-higher rates of neurological morbidity and total and gross-total resections were observed in the open resection group. Given the long survival of some patients, the EEE approach should be favored whenever reasonable.

Endoscopic resection of chordomas in different clival regions

CONCLUSION

The endoscopic approaches developed for the treatment of the chordomas according to the different clival location provide the possibility for more complete tumor resection with maximal preservation of anatomic structures and reduction of the overall incidence of complications.

OBJECTIVE

The endoscope has recently been applied in patients with chordomas, but rare studies report the various endoscopic approaches in the treatment of chordomas in the different regions of clivus. In this study, the authors present their experience with these techniques in patients with chordomas.

PATIENTS AND METHODS

Four chordomas in the upper-middle clivus underwent an endoscopic transseptal transsphenoidal (ETT) approach. Five macro-chordomas involving whole clivus underwent an extended ETT approach. Three chordomas in the lower clivus underwent an endoscopic transoropharyngeal (ETOP) approach. The surgical access points were designed for each patient. After safe planes were identified along the surgical access points, the tumor was fractionally removed.

RESULTS

Seven gross total, four subtotal, and one partial resection were achieved after surgery. At 6 months to 3 years follow-up, eight patients were recurrence-free and two patients had unchanged residual tumor. One patient with recurrent chordoma underwent second surgery and subsequent intensity modulated radiation therapy (IMRT). The other patient with a recurrent chordoma died 1 year postoperation.

Cranial base approaches to inaccessible intracranial tumors

PURPOSE OF REVIEW

Craniotomy created through the base of the skull has improved exposure of many types of extraaxial tumors and thus enhanced both tumor control and preservation of neural function. The purpose of this article is to review recent advances in this emerging field.

RECENT FINDINGS

Use of microscopes and endoscopes has allowed these procedures to become progressively less invasive. Electrophysiological monitoring has enhanced neural identification and preservation. The increasingly documented efficacy of stereotactic radiation for certain tumor types (e.g. meningioma, schwannoma) has permitted nonoperative therapy for some individuals. In large tumors, selective use of less-than-complete microsurgical resection is establishing an increasing role, at times combined with focused radiotherapy of the surgical remnant. The role for transbasal craniotomy is well established in both benign tumors and vascular lesions, but has only limited applicability for high-grade malignant lesions. Today, the vast majority of procedures can be conducted in a single stage by a multidisciplinary team.

SUMMARY

Operative trajectories created through the cranial base, although technically demanding, have led to substantially improved outcomes for a wide variety of inaccessible intracranial lesions.

Chondrosarcomas of the skull base and temporal bone

OBJECTIVE

To evaluate the clinical presentation and outcomes of treatment for patients with chondrosarcomas involving the skull base and temporal bone.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary medical centre.

PATIENTS

Cases of histologically confirmed chondrosarcoma involving the skull base and temporal bones.

INTERVENTION

Surgery.

MAIN OUTCOME MEASURES

Demographic features of presenting patients; presenting symptoms and signs; surgical approach employed; use of post-operative radiation therapy; histological grade of tumour; and interval of post-operative follow up.

RESULTS

Twelve patients were identified with chondrosarcomas involving the skull base, with post-operative follow up ranging from three to 33 years. The average age at presentation was 42 years. The most common presenting symptoms were diplopia, decreased visual acuity and headaches. Five of the 12 patients required multiple surgical procedures.

CONCLUSIONS

Patients with chondrosarcoma involving the skull base and temporal bone may present in a variety of ways. Surgical resection, even subtotal, in combination with radiation therapy, can often provide good tumour control over many years for these rare tumours.

Posterior Transpetrosal Approach: Less is More

Objective:

We describe our surgical posterior transpetrosal technique, particularly the transcrusal variant for lesions involving the upper and middle clivus, petroclival regions, and lesions that involve both the posterior and middle fossae.

Methods:

An outline of the posterior transpetrosal technique involved, particularly the transcrusal variant, is described. Important superficial landmarks are identified, and a radical mastoidectomy is performed. The antrum is identified and entered, and, upon completion of the mastoidectomy and when Trautman 's triangle is defined, the temporal and suboccipital craniotomies are completed. After bone flap elevation, dura opening, and incision along the middle fossa dura, the superior petrosal sinus is ligated and cut. Tentorium cut completion is at the incisura posterior to the trochlear nerve. Watertight dural closure and standard flap replacement and skin closure complete the technique.

Results:

Clival exposure and the degree of temporal bone resection increase. Operative freedom also increases with increased temporal bone resection, especially when going from the retrolabyrinthine to transcrusal variants. Little is gained in terms of operative freedom and exposure of the clivus with resection of additional temporal bone beyond that of the transcrusal variant, and resection carries the cost of increasing morbidity, especially with respect to VIIth and VIIIth nerve function.

Conclusion:

The posterior transpetrosal approach and the transcrusal variant provide a lateral operative corridor to lesions of the upper and middle clivus. The tran-scrusal variant provides increased exposure and operative freedom similar to that provided by the transcochlear approach while minimizing cranial nerve morbidity.

The challenges of revision skull base surgery

Because the skull base is an anatomically complex structure, skull base tumors can hide easily in the crevices that interconnect the intra- and extracranial spaces and intermingle with important neurovascular structures. Often, total surgical resection of these tumors is not possible, and even with postoperative adjuvant radiotherapy, some recurrences after treatment are inevitable. Early detection of recurrent skull base tumors requires clinical vigilance and periodic imaging studies. The management of recurrent skull base tumors presents many challenges beyond those associated with primary procedures. A multidisciplinary setting that includes modern microsurgery and stereotactic radiation therapy provides patients with optimal care.

Skull base chondrosarcoma originating from the petroclival junction

OBJECTIVE

To define the presentation of patients with skull base chondrosarcoma, to elucidate surgical strategies, and to identify the role of postoperative radiotherapy.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral center.

PATIENTS

All patients (n = 33) with skull base chondrosarcoma managed at our institution. The average follow-up time was 7.7 years (range, 0-20 years).

MAIN OUTCOME MEASURES

Tumor location, presenting symptoms, presence of residual or recurrent tumor, and mortality.

RESULTS

The most common tumor location was the petroclival junction (n = 29). Common presenting symptoms were diplopia (48%) and headache (45%). Surgical approaches included retrosigmoid, transtemporal, transfacial, and frontotemporal craniotomies. Biopsy only was performed in four patients, subtotal resection in 19 patients, and total resection in nine patients. Most patients received postoperative radiotherapy (82%). Follow-up revealed residual, stable disease in 28% of patients and recurrent disease in 24% of patients. The mean time to recurrence was 3.0 +/- 2.8 years. The lack of postoperative radiation was significantly correlated with an increased risk of recurrence (odds ratio, 28; p = 0.007) but incomplete tumor resection was not (p = 0.6). Life-table analysis revealed that the 5-year survival rate was 85% and the 10-year survival rate was 77%. Five patients died; four of the deaths attributable to recurrent disease.

CONCLUSION

The characteristic growth pattern of skull base chondrosarcoma is tumor eroding the petroclival junction. Current therapeutic strategy is resection through an extradural subtemporal craniotomy with removal of the petrous apex and clivus. Radical resection of uninvolved structures is often not necessary. Nonetheless, gross total removal is often achievable. Postoperative radiotherapy reduces the chance of tumor recurrence.