Trans-sphenoidal approach

In 1909, Kanavel developed an infranasal trans-septal approach to the pituitary gland. There had been many other approaches proposed previously, but all were very mutilating operations. Kanavel's approach had the advantage of preserving nasal function and appearance.

Between the years of 1912-25, Cushing used a sublabial trans-septal approach with some success. The main problems for these approaches were poor visibility, haemorrhage, high recurrence rates and uncertainty about the exact location of the lesion.

In the last 20 years, the trans-sphenoidal approach has become the treatment of choice for pituitary adenomas and has eclipsed the trans-frontal approaches. The major anatomical concerns for this approach are the degree of pneumatization of the sphenoid sinus.

The sublabial technique is widely used and was first proposed by Halstead in 1910. The gingival margin above the upper incisors is divided in a plane parallel to the teeth and the floor of the nose. The nasal mucosa is removed from the nasal spine and the floor of the nose. The nasal spine is then removed, and the septum is either removed or deflected laterally. A speculum is then placed to facilitate access to the vomer and to the anterior wall of the sphenoid sinus. The sphenoid sinus is then opened and using and image intensifier, access is made to the anterior wall of the pituitary fossa.

Hirsch was the first to propose the classic anterior endonasal trans-septal approach in 1909. This approach is still widely used today. The technique, like the sublabial technique, requires the laborious dissection of the septal mucosa.

In the late 1970's another approach was developed which was the posterior endonasal approach. This approach had the advantage of avoiding the septal deviation and sublabial dissection.

All of these techniques arrive at the pituitary gland via the sphenoid sinus. Having made an adequate window in the anterior wall of the pituitary fossa, the pituitary capsule is treated with the bipolar coagulator and opened either as a flap or a cruciate incision.

A characteristic bulge usually indicates the site of a microadenoma and a small incision in the gland allows it to present at the surface. The microadenoma is then removed by careful dissection. More extensive dissection is required when dealing with a macroadenoma.

One of the disadvantages of the trans-sphenoidal technique is the possibility of a CSF leak. For this reason, care must be taken to post-operatively pack the pituitary fossa and the sphenoid sinus. Muscle from the thigh or abdominal fat may be used. A piece of Iyodura may be placed over the incision in the capsule, and the nasal mucosa is covered in parafin gauze (soaked in antibiotic powder). Patients are advised not to blow their nose for some time after the operation.