Pituitary Radiosurgery for Management of Intractable Pain: Tokyo Women's Medical University Experience and Literature Review.

Surgical or chemical hypophysectomy has historically shown good effectiveness in management of intractable pain but has often been accompanied by serious complications. In contrast, high-dose irradiation of the pituitary gland and stalk provides comparable analgesic effects and is associated with minimal morbidity. Although its physiological mechanism remains elusive, pituitary radiosurgery using the Gamma Knife has demonstrated high clinical efficacy and safety in cases of both cancer pain and noncancer pain. According to the available data, this treatment provides at least a temporary analgesic effect in >80% of patients, usually within hours to days after the procedure. Although the pain relief is most prominent and durable in cases of metastatic bone disease, it is not limited to that pathological condition or to cases of hormone-dependent cancers. Nevertheless, the low-quality studies reported to date cannot support any meaningful clinical recommendations on use of pituitary radiosurgery. Therefore, additional well-elaborated clinical and basic investigations, preferably performed in a multi-institutional and prospective fashion, are clearly needed and may bolster further developments of this highly promising treatment modality.