Treatment of pain of diffuse metastatic cancer by stereotactic chemical hypophysectomy: long term results and observations on mechanism of action.

Stereotactic instillation of absolute alcohol into the sella turcica for pituitary destruction was carried out in 29 patients divided into two groups. Seventeen with prostatic carcinoma underwent a total of 19 injections with 94% good to excellent results that persisted throughout the remainder of the patient's life-span. The longest survival was 9 months. Brief relapses did occur, but spontaneous remissions were the rule. A second group of mixed cancers contained 12 patients who received a total of 13 injections. Eleven patients had good to excellent results that persisted in all but 1 patient. The longest survival was 7 months. Hormonal levels and prolactin stimulation tests failed to show any correlation between hormonal changes and pain relief. Naloxone reversal of analgesia did not occur. There was no loss of cognitive function shown on psychological testing. Pathological studies showed destruction of the pituitary gland, which was subtotal in some patients despite good pain relief. All examinations showed that the pituitary stalk was destroyed. Patients who survived longer also showed degeneration of the supraoptic and paraventricular nuclei of the hypothalamus and the median eminence. All but 1 patient with pain relief exhibited a lack of antidiuretic hormone (ADH) production. Interpretation of the data indicates that ADH or its associated neurophysins act as central pain transmitters. The production of these transmitters is decreased or abolished by chemical hypophysectomy through the destruction of hypothalamic nuclei.