Retrospective analysis of cystic craniopharyngeomas after intracavital irradiation with yttrium-90 colloid

Aim: The authors report about follow up the patients after intracavitary irradiation for cystic craniopharyngeoma. Material and Methods: For retrospective analysis 15 patients were selected. The volume of the cyst was determined by CT or MRI. For dosimetry Backlund's formula was used. The cumulative dose to the inner surface of the cyst wall was about 250Gy. 90Yttrium silicate colloid was administered directly during stereotactically (CT guided) surgery or through the Ommaya drainage system. Control scintigraphy was performed 2-3 hours after 90Y injection with gamma camera to detect possible leakage of the radioisotope. None of our patients showed evidence of this. In addition to this, the patients were checked daily to pay attention to visual function, neurological condition and possible meningeal irritation. Results: Cyst shrinkage was monitored by repeated CT examinations. CT cyst volume measurement analysed all patients before and 1,2,3 and 5 years after the treatment. In our study 45% of cysts decreased in volume during 4 month, shrinkage of the initial cyst volume was 75% after 1 year. The cyst disappeared nearly totally in 5 patients. Only 3 cyst remain unchanged and 90Y treatment was repeated. No patients developed a visual field defect or evidence of hypothalamic dysfunction after the treatment. The neuro-opthalmological state completely recovered in 2 patients and improved in 5 patients. The prognosis was good only when an intact optic discs in time of the treatment was present. In some cases the radioisotope was implanted at a late stage of the disease without the opthalmological and neurological improvement. One patient died due to pulmonary embolism one week after the procedure. One patient died within a one year of the treatment from complications related to a solid cystic recurrence. One of typical signs for recurrence was worsening of neuro-opthalmological state. Conclusion: From our results this intracavitary 90Y therapy is minimally invasive and very effective method without side effects. Instillation improves the quality of life. The best result can be expected in solitary cyst because the effect is limited to the cystic part of the tumour. Some cysts require more than one treatment. Our results demonstrate good outcome of this technique as primary therapy but also for patients who have exhausted many conventional means of treatment. This method plays important role in multimodality treatment of cystic craniopharyngeoma because there are low operative complications