INTERSTITIAL RADIOTHERAPY OF 25 PARASELLAR CLIVAL MENINGIOMAS AND 19 MENINGIOMAS IN THE ELDERLY - ANALYSIS OF SHORT-TERM TOLERANCE AND RESPONSES/

I-125 seeds were permanently implanted into 25 parasellar-clival menin giomas (median age of patients, 56 y) and 19 globoid meningiomas in th e elderly (median age of patients, 77 y) using stereotactic technique and 3-D dose planning. Total dose at the tumour margin was increased d uring the series from 100 Gy to 150 Gy. The procedure caused no mortal ity and no serious bleeding, but injury to the III cranial nerve due t o puncture occurred in one (4%) of the 25 parasellar-clival meningioma s. In two (4.5%) of the 44 cases the postoperative CT scan showed a mi splaced seed, located at the tumour surface. Nonenhancing hypodense ri ngs developed around the seeds ('hot spots') with a median diameter of 10.5 mm at 12 months corresponding to a median initial activity of 8. 7 mCi. In general, meningiomas responded by slow reduction in volume. The parasellar-clival meningiomas were followed-up for a median of 19 months (6-32), and so far 4 tumours have shrunk moderately, 13 slightl y, and 5 not at all. Pre-operative III, V or VI cranial nerve signs we re present in 17 patients and subsided in 8 of them. On the other hand , facial numbness developed or increased in 9 of the 25 patients, indi cating that the V nerve is rather sensitive to this type of irradiatio n. In the 19 meningiomas of the elderly, the median follow-up time was 14 months (5-26). The median relative tumour volume was 46% at 12 mon ths. Accounting for tumour-related deaths only, the actuarial survival rate was 78% at 12 months and 62% at 24 months. In general, brain oed ema persisted despite reduction in tumour volume. Stereotactic implant ation of I-125 seeds into intracranial meningiomas is relatively safe. Interstitial radiotherapy represents a potential tool in the control of medium-sized intracranial meningiomas with minimal brain oedema, bu t its long-term impact and untoward effects remain to be followed-up.