The hypophysis, or pituitary gland, secretes hormones and is located more or less in the middle of the basis of the skull. Tumours of this organ (adenomas) are benign and half of them produce excess hormone levels.
Hypophyseal adenomas cause symptoms that can be divided into three categories:
- As space-occupying lesions, they compress important structures, which causes symptoms such as headaches, hydrocephalus, restricted field of vision, weakened vision and even blindness.
- Disturbance of the normal physiological function of the hypophysis: hormonal disorders
- Excess hormone production: Acromegaly, Cushing's disease and prolactinoma
Tumours causing problems due to their volume must first of all be reduced in size. This is rarely achieved with medication, so a microsurgical procedure is necessary. Smaller hormone-producing adenomas are often successfully treated with medication. If the drug treatment is not sufficient or if the patient does not tolerate the drugs, here too microsurgery has to be carried out.
Because the microsurgical treatment (generally using the endonasal approach) is very effective not and not very stressful for the patient, the Gamma Knife is only used on recurrent tumours or those at very sensitive sites. Treatment with the Gamma Knife halts tumour growth in about 90% of cases. Hormone levels return to normal in 60-70% of patients with Cushing's disease, in about 60% of patients with prolactinoma and in only 40% of patients with acromegaly. Side-effects occur in 1-3% of cases.