GROWTH AND RUPTURE OF UNRUPTURED CEREBRAL ANEURYSMS BASED ON THE INTRAOPERATIVE APPEARANCE

The growth and rupture of 40 cerebral aneurysms was studied in 36 pati ents (14 men, 22 women; were average age, 51.8 years). Aneurysms were classified into five types according to the intraoperative findings: t ype 1, uniformly thin, smooth surface; type 2, thin neck and thick wal l, smooth surface with or without red and/or transparent portions; typ e 3, uniformly thick wall, smooth surface with or without red portions ; type 4, thick neck, bubbled or loculated thin wall at dome with or w ithout red and/or transparent portions; type 5, thick wall in entirety , irregular surface with or without red portions. Five were type 1, si x type 2, and 12 type 3. In four of the type 2 aneurysms, turbulence c ould be seen at the neck. In seven of the type 3 aneurysms, red and/or transparent portions were observed in the wall. Thirteen were type 4; nine of which had a bubbled or loculated wall with or without red and /or transparent portions. Four were type 5, with scattered red portion s but a thick wall. Type 1 aneurysms were 2-5 mm, most of types 2 and 3 were 3-6 mm, type 4 were 3-13 mm, and type 5 were more than 9 mm. Ty pes 1 and 2 had few local changes in the wall, suggesting that aneurys ms at this stage are stable. Type 3 is considered to be a transitional stage to type 4 from type 2. Type 4 aneurysms had some local changes within the wall including bubbles or loculi. We concluded that aneurys ms exceeding 4 mm have local pathologic changes in the wall and are cr itical. To prevent subarachnoid hemorrhage, aneurysms of this size sho uld be detected and surgically treated.