A number of milestones have marked the development of transphenoidal pituitary tumour resection this century. The introduction of head lamp illumination, followed by the use of the operating microscope and fluoroscopy have allowed Neurosurgeons to perform this surgery in a safe and highly effective manner. This midline approach avoids the brain retraction associated with intracranial approaches to this region.
Cushing operating on a transsphenoidal case wearing the headlight apparatus that has remained legendary for burning either his assistant or the nurse. The headlamp was made from an unshielded standard light bulb. ( From Cushing H. The Weir Mitchell Lecture Surgical experience with pituitary disorders. ) |
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Cushing was the first to describe the transseptal transsphenioidal approach to the sella turcica in 1912. Guiot and Hardy refined the technique and added intraoperative fluoroscopic guidance and the use of the surgical microscope. Since then, the approach has become the standard one for lesions of the sella. The most serious limitation of the standard transphenoidal approach is the very narrow surgical corridor. The narrow corridor limits the lateral and rostrocaudal view. This limitation can result in incomplete tumour resection or inadvertent injury to adjacent structures. Much of the dissection involved in standard transphenoidal surgery is done blindly, and the most significant mortalities result from inadvertent injury to the hypothalamus or carotid arteries. The standard transsphenoidal approach may employ a sublabial or nasal incision and requires a nasal speculum. This can result in septal perforation, tearing of the nostril, recurrent nose bleed, tooth analgesia, sinusitis and mucocoele.
Currently endoscopic sinus surgery is accepted as a safe method of sinus surgery for inflammatory and polypoid conditions of ethmoid and sphenoid sinuses. Building on this experience, otolaryngologists accumulated considerable expertise in pituitary tumour resection aided by endoscopic techniques. The endoscope's short (5 to 15 mm) focal length enables a panaromic view of the sella with excellent magnification and illumination superior to the operative microscope. Angled scopes allow the surgeon to view the lateral parasellar and suprasellar areas. The improved sella visualization possible with the endoscope reduces carotid and hypothalamic injury and makes it possible to remove the tumour completely. |
Our Technique :
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We use a purely endoscopic approach for removal of pituitary tumours. Most operations are performed using a 17 cm long, 4 mm, 00 endoscope. Additional 300 telescope can provide oblique views into the sella, facilitating complete tumours resection. The same instruments used in standard microsurgical approach as well as endoscopic sinus surgery instruments are used for the endoscopic approach to the pituitary. We use powered drills whenever we come across thick bony sphenoid wall or there is pre-sellar pneumatisation of sphenoid. We have used fluoroscopic C-arm only in two cases where there was pre sellar pneumatisation of sphenoid.
Operative technique:
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General endotracheal intubation with general anesthesia is used. Face and nostrils are prepared using a 5% povidone iodine solution and a thigh is prepared for possible harvesting of fasia lata and muscle graft.
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Nasal mucosal vasoconstriction is achieved with topical xylomethozoline and 2% xylocaine with 1:100,000 epinephrine is injected in the posterior part of bony nasal septum, spheno-ethmoid recess and posterior end of middle turbinate on the roomy side of the nose. The middle turbinate and the superior turbinate are outfractured using Freer's elevator. This manoeuver exposes the sphenoethmoid recess and the ostium of the sphenoid sinus well. The ostium is widened.
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The posterior portion of the nasal septum is dissected at the level where sphenoid rostrum and perpendicular plate of ethmoid joins, to reach the contra lateral half of the sphenoid sinus sub-periosteally. The contralateral sphenoid ostium is widened. Then the sphenoid rostrum is removed and the opening in the anterior wall of the sphenoid sinus is completed. Inside the sphenoid sinus there may be single or multiple septas. Sufficient amount of the septa are removed to expose the sella, carotid prominence, optic prominence and opto-carotid recess. Whenever possible attempts are made to remove the mucosa covering the sella only to avoid unwanted troublesome bleeding.
The condition of the floor of the sella is subject to the type of lesion found in the sellar cavity. It is nearly always intact when the lesion is a craniopharyngioma, Rathke's cleft cyst or a pituitary microadenoma. It is often thinned and/or eroded in the presence of a pituitary macroadenoma. Depending on the condition, the sella floor can be opened using chisel or a dissector and it is enlarged with Kerrison punches. The dura is coagulated and a cruciate incision is made using a scalpel.
The tumour is removed using suction and various angled curettes. As the tumour is removed, the endoscope is advanced into the empty pituitary fossa. 300 telescope is used to visualize the entire sella and ensure complete resection and avoidance of important structures such as the cavernous sinus and internal carotid arteries. After tumour removal, haemostasis is secured. If cerebrospinal fluid (CSF) leak is seen during the operation, the sella is packed with fat or muscle graft. Nasal packing is usually not required.
With practice, exposure of the sella can be achieved significantly faster than with standard microsurgical techniques. The decreased nasal dissection involved obviates the need for postoperative nasal packing and the associated post-operative patient discomfort. The angled endoscopes allow a full sella view, and surgery does not require blind dissection for tumour resection.
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Our experience:
From January 1997 to October 2003, our team at the Apollo Speciality hospital has carried out 124 endoscopic pituitary surgeries successfully. Out of 124 sellar lesions we managed, there were 107 pituitary adenomas, 5 craniopharyngiomas, 2 meningiomas, 2 Rathke's cleft cysts, 5 inflammatory lesions and 2 malignant tumours. Youngest patient we have operated sofar was 8 years old and the age of the patient need not be a limiting factor.
Complications:
In our series of 124 cases, we didn't have any major vascular injury or injury to optic nerve or hypothalamus. We had 4 cases of temporary diabetes insipidus (DI) and none had permanent DI. Patients who were detected to have CSF leak during surgery were managed successfully and none had leak during the postoperative period. Only one patient had CSF leak 3 weeks after surgery while receiving radiotherapy and developed meningitis.
Conclusion:
Surgery for pituitary lesions has become greatly refined from the time Cushing described transsphenoidal approach. Endoscopic transsphenoidal pituitary surgery is now a proven and safe method of removing pituitary lesions and has been embraced as the preferred technique the world over.
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Nasal phase of surgery unnecessary 
