Skull Base Surgery

The base of the skull is a complex and relatively inaccessible region. Pathology in this area may arise from either within the skull itself or from adjacent areas such as the paranasal sinuses, the orbit and the face.

Conventional approaches to skull base lesions frequently require prolonged retraction of the brain and/or the resection of uninvolved structures to improve exposure. The resultant morbidity of such techniques, in terms of both cerebral function and facial appearance were often considerable with the result that many deep-seated skull based tumours were considered inoperable. The limited access also made adequate reconstruction of defects difficult and, in some cases, impossible.

Recent developments in surgical approaches to the skull base are based on the temporary disarticulation or dismantling of the skeleton of the face and the skull to varying degrees. These bone segments are mobilised either as free bone segments, completely detached from the soft tissues, or pedicled to the soft tissues to retain their blood supply. In most cases the so-called "access osteotomy" is combined with a conventional craniotomy. Facial incisions are avoided wherever possible - the coronal scalp flap and intraoral incisions providing adequate exposure in many cases. If facial incisions are necessary, these are carefully sited and will usually heal with an imperceptible scar.

Maxillofacial Surgeons, by virtue of their training in surgery of the facial bones and soft tissues, have contributed significantly to the development of the surgical access techniques now in common practice. The field of skull base surgery is developing rapidly. Sophisticated imaging techniques accurately identify both the position and dimensions of lesions and, in some cases, correctly diagnosing their nature. Interventional radiologists can reduce the blood supply of tumours and vascular abnormalities further decreasing the potential morbidity of surgery, which at times allows surgeons to treat previously inoperable lesions.

The recent development of "navigation" systems enables surgeons to pinpoint their position in three dimensions at the time of surgery, which is of particular value where the pathology has destroyed the usual anatomical landmarks. The selective use of minimally invasive techniques and focused radiosurgery will also become more common as the limits of such techniques are appreciated. Notwithstanding these developments, adequate access to skull base pathology will remain an essential requirement for successful surgical treatment.