INTRACAVITARY IRRADIATION WITH COLLOIDAL P-32 FOR TREATMENT OF AN ARACHNOID CYST - A NEW APPROACH

Intracavitary irradiation is reported as an additional treatment for i ntracranial arachnoid cysts that do not communicate with the subarachn oid space. A 46-year-old woman with a large suprasellar arachnoid cyst that had enlarged over a 4-year interval presented with new onset hea daches. Stereotactic intracavitary irradiation was performed using col loidal phosphorus-32 as an alternative to craniotomy or insertion of a shunt. Total regression of the cyst occurred within one month with re solution of her headaches. After three years of follow-up, imaging stu dies showed only an empty sella appearance, and no cyst recurrence. No early or delayed morbidity occurred. Intracavitary irradiation may be a useful therapy for arachnoid cysts, in an attempt to alter the biol ogy of the cyst lining.