Radiologic and histopathologic changes after Gamma Knife radiosurgery for XXXX .

@entity5 @entity1 @entity5513 @entity45
Gamma knife radiosurgery (GKRS) is a widely used treatment option for @entity5513 , 3 cm in diameter or less. Between May 1990 and February 1998, 102 @entity5 in 101 @entity1 were treated with GKRS. There are 77 @entity1 with a follow-up period of more than six months (mean 55, range 7 to 90 months). Seventy (91%) of these @entity5 have remained unchanged or reduced in volume. After GKRS there was an increase in volume in seven cases. In four the volume increase affected solid @entity5 . Among these, three @entity1 were in stable condition and are being observed. One of these @entity1 developed brain stem compression symptoms and was operated. In another three cases, @entity45 with multiple septa developed medial to the @entity5 and compressed the brain stem and fourth ventricle, thus necessitating post-GKRS surgery. In these three @entity1 , MRI had shown loss of central contrast enhancement followed by its return. Histological findings at surgery before and after GKRS were compared for these four @entity5 . In spite of the MRI changes, there were no definite histological findings after GKRS which could be attributed to radiation induced changes. The development of @entity45 occurred after the treatment of larger @entity5 .
