Anterior skull base tumour. The choice between cranial and facial approaches, single and combined procedure. From a series of 78 cases

Celebrating the golden anniversary of anterior skull base surgery: reflections on the past 50 years and its historical evolution

With its inception nearly half a century ago through the pioneering work of Dandy, McLean, and Smith, anterior skull base (ASB) surgery is a relatively young discipline. It became a distinct entity in 1963 when Ketcham popularized the combined transcranial transfacial approach for en bloc resection of tumors of the paranasal sinuses extending into the anterior cranial fossa. However, because these procedures resulted in major morbidities and mortalities, alternative modes of treatment were sought. Since the 1970s, the introduction and promotion of the surgical endoscope by Messerklinger, Stammberger, and Kennedy, commenced the era of endoscopic sinus surgery. Thaler and colleagues described the utility of the endoscope for ASB surgery at the turn of the century. This allowed direct visualization and safer, more accurate removal of tumors. In 2001, Casiano reported the first purely endoscopic endonasal ASB resection, a novel technique that has been adopted by major skull base centers. The success of ASB surgery can be attributed to both the development of the skull base team as well as improvements in surgical techniques, instrumentation, and visualization technology. In this article, we review the historical evolution of ASB surgery as we approach the 50th anniversary since its recognition as a distinct entity.

Proposed classification for the transbasal approach and its modifications

The transbasal approach offers extradural exposure of the anterior midline skull base transcranially. It can be used to treat a variety of conditions, including trauma, craniofacial deformity, and tumors. This approach has been modified to enhance basal access. This article reviews the principle differences among modifications to the transbasal approach and introduces a new classification scheme. The rationale is to offer a uniform nomenclature to facilitate discussion of these approaches, their indications, and related issues.

Quantification of clival and paraclival exposure in the Le Fort I transmaxillary transpterygoid approach: a microanatomical study

OBJECT

The authors describe a modified Le Fort I maxillotomy with medial and posterior antrectomy and removal of the pterygoid plates, aimed at improving the lateral surgical exposure during open transmaxillary surgery for pathological conditions involving the clivus. A cadaveric microanatomical study was conducted to compare the planimetric exposures allowed by the transmaxillary transpterygoid (TMTP) approach and the standard Le Fort I maxillotomy (STM).

METHODS

Six cadaveric specimens that had been fixed with glutaraldehyde and injected with latex were dissected to obtain morphometric measurements after both TMTP and STM approaches. The anatomical areas exposed by the surgical approaches were calculated using ImageJ 1.37a software.

RESULTS

As expected, the TMTP approach allowed for a greater surgical exposure, with an incremental area exposed ranging from 4.9 to 7.6 cm(2) (mean ± standard deviation 6.4 ± 1.2 cm(2), 95% CI 5.4-7.4 cm(2)). The amount of additional anatomical area visualized, as recorded as a percentage increase after the TMTP approach when compared with the STM approach, ranged from 83 to 109% (mean 99%).

CONCLUSIONS

The lateral surgical exposure allowed by the STM approach is limited by the pterygoid plates. The TMTP approach significantly improves the exposure of the anatomical regions lateral to the clivus, allowing access to the pterygopalatine and medial infratemporal fossae. In comparison with the STM, the TMTP approach allows for a surgical exposure that is nearly double. The authors conclude that the TMTP approach provides a significant improvement in the surgical exposure of the lateral paraclival areas, when compared with the STM approach.

Transcranial combined neurorhinosurgical approach to the paranasal sinuses for anterior skull base malignancies

OBJECTIVE

Various transcranial and transfacial approaches have been described and each claims to provide the best exposure to the anterior skull base. Similarly, each approach claims the best outcomes following the resection of anterior skull base malignancies. We have always advocated a combined neurorhinological approach for the management of paranasal sinus malignancies that infiltrate the skull base, such as esthesioneuroblastomas.

MATERIALS AND METHODS

At the outset, the technique was developed on cadaver specimens, imitating the limitations that might be imposed in the real-life situation when undertaking endoscopic sinus surgery. Additional exposure of the anterior cerebral fossa was achieved using a classical bifrontal approach. Starting with endoscopic or microscopic unroofing of the ethmoids, all relevant landmarks were identified. The frontal, sphenoid, and maxillary sinuses were then opened using endoscopic techniques.

RESULTS

The dissections proved that a broad exposure of the anterior skull base could be combined with clear endoscopic visualization of the nasal cavity and of all the paranasal sinuses from above. This facilitated complete eradication of lesions from the sinuses cavities, their walls, and the intracranial tumor.

DISCUSSION

The combined neurorhinosurgical transcranial approach to the anterior skull base and nasal and paranasal sinuses, avoiding trans-facial approaches, enables a multidiciplinary team to resect malignant tumors of the anterior skull base directly without unnecessary destruction of facial structures. It appears to provide better access than other more destructive methods like midfacial degloving or subfrontal approaches. Our single-stage approach also facilitates safe and effective reconstruction of the skull base. The technique can be employed for tumors of all sizes and is also used for orbital resections and decompression of the optic nerve and chiasma.

Surgical Strategies for Recurrent Craniofacial Meningiomas

OBJECTIVE:

Recurrent cranial base meningiomas are among the most difficult tumors to treat surgically. Although they are histologically benign, these tumors often invade through the cranial base into the infratemporal and pterygopalatine fossae. We reviewed our experience with these tumors to describe the natural history of these lesions as well as provide a possible treatment paradigm.

METHODS:

Between 2000 and 2004, seven patients with meningiomas recurring through the cranial base into facial structures were treated at the University of Utah. Five patients were treated with transcranial approaches only, and two were treated with a combination of transcranial and transfacial approaches.

RESULTS:

The average age of our patients (6 women, 1 man) was 55 years. The original site of tumor was the sphenoid wing in four patients, the middle fossa in two patients, and the left frontal region in one patient. The average interval between the most recent tumor resection and recurrence into the face was 9.9 years. The mean number of resections a patient underwent before invasion into the face was two. All but one patient had adjunctive therapy (including either radiation or chemotherapy) before recurrence into the face.

CONCLUSION:

Meningiomas that recur into facial structures present a unique treatment challenge. These lesions have a high rate of recurrence once they have invaded through the cranial base. Although combined approaches may be necessary to achieve a gross total resection, these lesions can often be reached using standard transcranial techniques.

Transbasal approach to skull base tumors: evaluation and proposal of classification

A clinical study of the TBA was performed in 22 patients harboring tumors of the skull base. The follow-up ranged from 3 to 89 months (average, 30.5 months). The main complications were intracerebral hematoma, ptosis, and infection. One patient died (4.5%) because of an extradural hematoma. Eight patients died during the follow-up because of tumor complications. Among the survivals, the median of the Karnofsky index was 96.4. Based on this study, we propose a classification for the TBA, according to its extension.

Reconstruction après résection tumorale de la base antérieure du crâne par greffon graisseux abdominal

OBJECTIVES

Reconstruction of the anterior skull base is a surgical stage as significant as tumor removal. The quality of the reconstruction is the primary determinant of postoperative mortality, morbidity. The aim of our work was to assess the results of a reconstruction process combining: 1) a pericranium graft held by biological glue to complete the dura mater; 2) an abdominal fat graft supported by a Silastic arch to maintain the neurological structures.

PATIENTS AND METHODS

This was a retrospective study. 55 patients (44 men and 11 women), 59 mean age (14 - 78), were analyzed. 45 had a malignant tumor and 10 a benign tumor. 35 patients were treated using a mixed approach and 18 using a trans frontal-sinus approach alone. Forty-three patients treated for a malignant tumor underwent postoperative radiotherapy. Results were analyzed according to 3 periods: 1) immediate postoperative period (<25 days); 2) early postoperative period (25 days - 3 months); 3) late postoperative period (> 3 months).

RESULTS

None of the patients were lost to follow-up. The average follow up was 84 months. All periods considered together, we had five (9.4%) graft infections, 6 (11.3%) CSF leaks and 1 (1.8%) cases of meningitis.

CONCLUSION

We use a simple technique for reconstruction. Postoperative complications were exceptional, even after postoperative radiotherapy. Medium and long-term results are good and similar to those obtained with other processes used for reconstruction of the anterior skull base reconstruction.

Surgical strategies in the removal of malignant tumors and benign lesions of the anterior skull base

The choice of surgical approaches to the tumors of the anterior skull base is determined by the location, dimensions of such lesions and their relations to the surrounding structures. Furthermore, the need for the reconstruction of the dura and skull base structures has an important influence on the decision about the surgical procedure. Transfacial approaches provide limited exposure, especially when tumors damage the floor of the anterior cranial fossa and involve the frontobasal dura and brain. Transcranial, craniofacial and subcranial approaches in particular may aid a surgeon in the removal of such lesions, and often these surgical procedures are the only beneficial methods. Our study comprised 15 patients. Transcranial approaches were used in ten cases. In five further cases, we adopted craniofacial or subcranial approaches. Total removal of these lesions was possible in 13 cases. Neither important complications nor death after surgery was observed except for two cases (craniofacial/subcranial approach) where the CSF leak and CNS infection were reported. We deem that the transcranial approach creates a good possibility for total removal of anterior skull base tumors, particularly of the benign lesions, and permits reconstruction of the skull base damaged by the tumor. However, in patients with large malignant tumors, the en bloc resection via the combined craniofacial/subcranial approach achieved better outcome.

Anterior transcranial (craniofacial) resection of tumors of the paranasal sinuses: surgical technique and results

Transfacial approaches, traditionally used for malignant tumors of the paranasal sinuses, provide limited exposure when several sinuses are involved and are unsuitable for tumors that erode through the floor of the anterior cranial fossa. A transcranial approach may aid in the removal of such lesions. To better understand the risks and benefits of this surgical approach, we reviewed all patients (n = 76) who underwent a transcranial approach as part of the excision of paranasal sinus lesions between 1984 and 1993 at our institution. The spectrum of disease included adenocarcinoma (13 patients), squamous cell carcinoma and olfactory neuroblastoma (11 patients each), adenoid cystic carcinoma and poorly differentiated forms of carcinoma (6 patients each), melanoma (5 patients), and miscellaneous others (24 patients). Most patients had ethmoid sinus involvement; tumors were also commonly found in the cribriform plate, sphenoid sinus, and nasal fossa. In each patient, a bifrontal craniotomy was performed with extradural dissection to the floor of the anterior fossa and osteotomies for resection of involved elements. In 47 patients (62%), disease in the orbit, the anterior nasal cavity, or the soft tissues of the face required transfacial as well as transcranial resections. Bony defect in the anterior fossa floor was repaired with a pedicled pericranial flap. Patients with major complications included six patients with epipericranial and/or epidural hematomas requiring evacuation, three with transient cerebrospinal fluid leaks, two who developed bifrontal cerebral infarcts, and one who died soon after surgery. No meningitis was seen. To date, 26 patients (34%) have died; of those living (mean follow-up, 34 mo), 42 (84%) remain in full remission. The transcranial approach can achieve removal of erosive, invasive tumors from this area with predictable morbidity and may be considered whenever sinus tumors breach the anterior cranial base or extend beyond the reach of conventional transfacial approaches.

Cranio-facial approaches for tumours involving the anterior half of the skull base

Teamwork between neurosurgeons and head and neck surgeons has increased the possibility of managing tumours involving the skull base. The authors distinguish the anterior half of the skull base into a median and two lateral portions and describe the surgical approaches utilized to expose it. The authors present their clinical experience in 27 patients with extensive lesions of the anterior half of the skull base and their results.