Stereotactic radiosurgery of pituitary adenomas.

The first gamma knife (GK) treatment of a pituitary adenoma in 1967 was meant as an alternative to the primitive surgical approaches that prevailed at the time, with consequent unsatisfactory results. Surprisingly, pituitary adenomas still account for only 7.8% of the 27,000 cases treated in GK centers worldwide. Transnasosphenoidal surgery has greatly improved and surgeons are reluctant to give up a relatively safe and effective operative technique. Radiosurgery is not currently vying to be the primary method of "surgery", but has a definite role following failed pituitary surgery and for tumors that extend into the cavernous sinus. Of 300 patients treated in our GK service, 30 had pituitary adenomas and most had undergone surgery. To date, we have not noted any side effects in the pituitary group. Published information is also reviewed and divided, where possible, into the pre-computed tomography (CT) era and the era of CT-magnetic resonance imaging (MRI). Growth hormone (GH)-secreting adenomas and prolactinomas tend to be larger and cannot be treated with the high doses successful against corticotropin (ACTH)-secreting tumors in Cushing's disease. Radiation fall-off is steep in GK radiosurgery, with the 20% isodose curve being only millimeters away from the point of maximal radiation. The effective dose has mostly been decided on the basis of maintaining safe levels at the sensitive perisellar neural structures. The safety of GK treatment (with no mortality and no permanent morbidity) is compared with other radiosurgical techniques. Good patient response owes much to the cumulative experience of GK pioneers and also to recent advances in images and computers that have enabled increasingly precise stereotaxic targeting and dose planning.

Effect of intracerebroventricular infusion of epidermal growth factor in rats hemitransected in the nigro-striatal pathway.

The most recent attempt at surgical treatment of Parkinson's disease is represented by implant of dopaminergic tissue in the striate nuclei. Growth factors have been associated to the neural implants in order to favor successful grafting and functional survival. Among diverse growth factors Epidermal Growth Factor (EGF) is active in vitro on axonal regeneration of dopaminergic cells of the substantia nigra. Our research group has recently assessed the effect of a 35-day delayed intracerebroventricular infusion of EGF on the survival and function of the dopaminergic neurons in rats made hemiparkinsonian by unilateral mechanical transection of rat nigrostriatal pathway. EGF infusion resulted in a two-fold increase in the number of surviving tyrosine hydroxylase (TH)-positive substantia nigra neurons and a significant increase in ipsilateral striatal TH-positive fiber staining compared to controls. In addition there was a persistent enhancement of behavioral recovery, as indicated by a reduction in amphetamine-induced rotations. In the present study EGF is tested at a lower dosage starting administration at the time of lesion. Effects have been assessed by the available functional and biochemical methods. Results confirm that neurotrophic effect of EGF on dopaminergic neurons in the nigro-striatal pathways follow early administration also at low dosage.