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ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge
7th Congress of the European Skull Base Society held in association with
the 13th Congress of the German Society of Skull Base Surgery

18. - 21.05.2005, Fulda, Germany

The subcranial approach to the anterior skull base

Meeting Contribution

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  • Dan M. Fliss - Department of Otolaryngology Head and Neck Surgery, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
  • Ziv Gil - Department of Otolaryngology Head and Neck Surgery, Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge. 7th Congress of the European Skull Base Society held in association with the 13th Congress of the German Society of Skull Base Surgery. Fulda, 18.-21.05.2005. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc05esbs06

DOI: 10.3205/05esbs06, URN: urn:nbn:de:0183-05esbs062

Published: January 27, 2009

© 2009 Fliss et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Introduction

The surgical treatments used for tumors involving the anterior skull base have evolved over the past 30 years. Despite the technical reproducibility of the classic approaches, modifications are continually being designed to enhance access to this anatomical region and improve the functional and the cosmetic postoperative results. The concept of a broad subcranial approach to the entire anterior skull base from the ethmoidal labyrinth roof to the clivus and laterally to the orbital roofs was first introduced by Raveh in 1978 in cases of traumatic injuries of the anterior skull base as an alternative to the traditional transfacial-transcranial skull base approaches [1]. It was later adapted for the surgical extirpation of tumors involving this anatomic region. The procedure is performed with minimal frontal lobe manipulation, the avoidance of external facial incisions, and adequate drainage of the subcranial compartment.

The purpose of this chapter is to review the medical and surgical management of patients operated for anterior skull base tumors via the subcranial approach.

The surgical technique of the subcranial approach

A bicoronal flap is created in a supraperiosteal plane. The pericranial flap is elevated up to the periorbits, and the supraorbital nerves and vessels are carefully separated from the supraorbital notch. An osteotomy of the anterior or the anterior and posterior frontal sinus walls, together with the nasal bony frame, part of the medial wall of the orbit, and a segment of the superoposterior nasal septum, is then performed [2], [3]. A bilateral ethmoidectomy and a sphenoidotomy are performed: this approach enables the exposure and assessment of the tumor in its circumference. The tumor is extirpated at this stage and the dura or brain parenchyma is also resected when involved by tumor.

In our series, we used a double layer fascial sheath as the standard procedure for anterior skull base reconstruction. The flexibility of the fascia lata enables coating of extensive cranial defects, including parts of the orbit and paranasal sinuses. Large cranial base defects and prior surgery and radiotherapy (previously considered indications for free flap reconstruction) were managed by fascia alone [4].

Surgical results

A retrospective evaluation of patients undergoing anterior skull base surgery was based on a review of the hospital charts and the outpatient clinical and radiological data of 189 consecutive cases operated between 1994–2005. All the resections and reconstructions were carried out by means of the subcranial approach to the anterior skull base. The patients aged 2–81 years (mean 42 years). 102 patients were operated for extirpation of anterior skull base tumors, 55 following craniobasal fractures, 15 due to cerebrospinal fluid leak, 7 to treat fungal and other infections (i.e. abscess and osteomyelitis) and 3 for reconstructive procedures following neurosurgical procedures. In this chapter we report our experience with tumor resections of 44 malignant tumors (43%) and 58 benign tumors (57%). Figure 1 [Fig. 1] shows a typical case of a patient with squamous cell carcinoma. The most common malignant tumor was squamous cell carcinoma and the most common benign pathology was meningioma. 32 patients (31%) had undergone at least one previous operation and radiotherapy. The subcranial approach was used as a single procedure in 83 cases. It was combined with a midfacial degloving procedure in 11 cases, with transfacial/transorbital approaches in 7, with a pterional approach in another 6 and with transnasal endoscopic approach in 3 patients.

The mean hospitalization period was 10 days. The overall complication rate among patients operated for extirpation of tumors was 30%. However, the incidence of CSF leak, intracranial infection and tension pneumocephalus was 3%. Osteoradionecrosis with fistula was found in 5 patients, 4 of whom had undergone perioperative radiotherapy. Because of the risk for osteoradionecrosis of the fronto-naso-orbital segment in patients who undergo perioperative radiation therapy, we developed a new method for skull base reconstruction. In these cases we used the pericranial flap for wrapping the NFO segment. There were no cases of bone flap necrosis in the patients who underwent this procedure.

Conclusions

We routinely used the subcranial approach for tumors involving the anterior skull base. Wide exposure of the tumor area enables meticulous dissection, minimizes brain retraction and allows full control of blood loss with preservation of vital anatomical structures. Finally, our work indicates that the overall QoL in the majority of patients after subcranial surgery can be classified as good, with significant improvement within 6 months following surgery [5].


References

1.
Raveh J, Schwere. Gesichtsschädelverletzungen: eigene Erfahrungen und Modificationen. Aktuel Probl ORL. 1979;3:145-54.
2.
Gil Z, Cohen JT, Spektor S, et al. Anterior skull base surgery without prophylactic airway diversion procedures. Otolaryngol Head Neck Surg. 2003;128:681-5.
3.
Fliss DM, Zucker G, Cohen A, et al. Early outcome and complications of the extended subcranial approach to the anterior skull base. Laryngoscope. 1999;109:153-60.
4.
Fliss DM, Gil Z, Spektor S, et al. Skull base reconstruction after anterior subcranial tumor resection. Neurosurg Focus. 2002;12:10.
5.
Gil Z, Abergel A, Spektor S, Cohen JT, Khafif A, Shabtai E, Fliss DM. Quality of life following surgery for anterior skull base tumors.Arch Otolaryngol Head Neck Surg. 2003;129(12):1303-9.