27 Endoscopic Cavernous Sinus Surgery

Giorgio Frank, Diego Mazzatenta, Vittorio Sciarretta, Matteo Zoli, Giovanni Farneti, and Ernesto Pasquini

Introduction

A single gold standard in cavernous sinus (CS) surgery does not exist, because the technique must be adapted to the features of the particular tumor. Anterior extracranial approaches and transcranial approaches are complementary, and both techniques facilitate obtaining the best surgical result with the minimal morbidity. Both have to be in the armamentarium of the skull base surgeon operating on CS tumors. Anterior extracranial approaches present three advantages over the transcranial approaches: (1) They are extracerebral, avoiding any brain manipulation. 2) They enable penetrating the CS through the medial wall, which is devoid of any nerves. Conversely, in transcranial approaches, the CS is penetrated, crossing the lateral wall through narrow windows between the cranial nerves. (3) Working within the CS in anterior extracerebral approaches, there are areas, such as the medial and the posterosuperior compartments, that do not run the risk of nerve damage, and there are others area, such as the anteroinferior and the lateral compartments, that have a well-defined point where there is a risk of nerve damage. The abducens nerve (cranial nerve VI) runs the main risk of damage because it runs free in the CS space; the others nerves are embedded and protected between the two layers composing the lateral wall of the CS (Fig. 27.1).

The main disadvantage of anterior extracerebral approaches is the difficulty of controlling the carotid artery and protecting it from injury. Jho and Carrau¹ in 1997 reported the first series of pituitary adenomas treated using an endonasal endoscopic technique. Since that time, we have recognized the possibility of extending this technique to use it in surgery of the parasellar region. One year later we started our experience with endoscopic endonasal surgery of the CS, and our preliminary results were reported to the Fifth European Skull Base Society Congress in 2001.² We prefer the endoscopic technique because it overcomes the limitations of the microsurgical technique,³ such as the necessity to utilize wider surgical channels with limited peripheral vision, and the necessity to utilize metallic retractors.

We recommend the endoscopic approach only to surgeons who are well trained with this technique and only in centers where endovascular support is available, and where it is possible to switch to open surgery, if needed.

Selection Criteria

The selection criteria for an endoscopic CS surgery are mainly the biological behavior of the tumor and its location. Tumors involving the vessels and nerves, such as meningiomas and carcinomas, are not good candidates for this approach (Fig. 27.2). Conversely, tumors not involving the vessels and the nerves, such as adenomas and chordomas or chondrosarcomas, are amenable to this type of surgery. The consistency of the tumor may be a further criterion for selecting the endoscopic approach, with soft tumors being more suitable for this type of surgery. Only tumors that are totally extradural or have limited intradural extension are suitable for endonasal endoscopic approach. But if the tumor has a large intradural extension, we use the transcranial approach.

Technical Note

A detailed description of our endonasal approach to the CS is available elsewhere.^4–7 In this chapter we focus on the tips and pearls that can result in a successful operation.

The mechanical holder maintains the position of the endoscope during the crucial phase of the procedure; it enables both surgeons to work bimanually, permitting safe and precise adjustments of the position of the optics, which is necessary to avoid instrument crowding and to provide the best vision of the surgical field (Fig. 27.3).