Role of Stereotactic Radiosurgery in Pituitary Adenomas.

Pituitary adenomas are one of the common indications for gamma knife radiosurgery. Gamma knife enables one to deliver a very high radiation dose to the target in a single fraction. Due to steep radiation fall out of Gamma Knife, the adjacent visual apparatus gets minimal radiation. The aim of stereotactic radiosurgery for pituitary adenomas is to stop tumor growth, normalize hormonal hypersecretion, preserve pituitary function, and protect important surrounding structures. Surgery is the treatment modality of choice in the management of pituitary adenomas and gamma knife radiosurgery is restricted for residual or recurrent lesions only. The acceptable marginal dose for non-functional adenomas is 12 Gy. Control rates varies from 76-87% at 10 years are described in non-functional pituitary adenomas. In functional adenomas, to achieve hormonal remission a higher marginal dose up to 25 Gy is needed. However, primary gamma knife radiosurgery is needed in some situations - for instance, when the patient is unfit for surgery due to various reasons or surgical difficulties like the presence of kissing carotids.