Hardy's classification, as discussed in Chapter 7, allows a formal description of tumor size that remains helpful in defining likely candidates for a trans-cranial operation.
The merits of a transcranial operation for a large tumor depend on the clinical indication for surgery. For patients with visual failure, one apparent advantage of the transcranial approach is the direct view of the optic apparatus and the adjacent tumor. One might believe that this allows a better decompression of the optic apparatus than is possible with a transsphenoidal operation. This was the belief of the early exponents of pituitary surgery; Harvey Cushing found that recovery of normal vision occurred in 21% of his transfrontal cases, compared with 9% of those operated on via the transsphenoidal route (7). In the modern era, however, it is clear that excellent visual results have been obtained from transsphenoidal surgery (8,9) and visual failure does not normally indicate the need for a transcranial operation.
For treating hormone excess, complete resection of the adenoma, which is required for cure, is most frequently achieved when the tumor is small and is approached transsphenoidally. Large endocrine tumors, on the other hand, are more difficult to cure irrespective of the approach; even an exemplary resection is not necessarily rewarded with a cure. Other characteristics of the tumor, apart from the size, may have a negative influence on endocrine outcome, especially the presence of dural or cavernous sinus invasion. As Laws observed in a
Indications for Transcranial Surgery Tumors with a large suprasellar component Recurrent tumors with visual failure Abnormal skull-base anatomy Tough fibrous tumors A small or underpneumatized fossa reviewer's remark: "It is naive to think that one can perform a total removal of an invasive pituitary adenoma" (10). Hence a complex transcranial procedure whose aim is to remove every fragment of tumor is likely to fail. Rather, the aim should be to remove as much tumor as possible in order to optimize the benefits of subsequent drug treatment or radiotherapy.
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