Effect of Mannitol and Betamethasone on Postischemic Brain Edema in Rabbits

The study is to evaluate the effect of mannitol and betamethasone on postischemic brain edema. Brain ischemia was produced by transient occlusion of the both common carotid arteries with the vascular clip for duration of 3 minutes and 5 minutes. Each group was recirculated for 30 minutes, 1, 2, 3 and 6 hours after removing the clips from the arteries. Of 40 rabbits, twenty rabbits were untreated as control and the other twenty rabbits were treated with a combination of mannitol(2 gm/kg) and betamethasone(1 mg/kg) intravenously at 20 minutes before the occlusion. The water content, amount of Na and K were measured and compared with each group between the 3 minute and 5 minute occlusion groups, and between the control group and treated group with mannitol and betamethasone. The experimental results were summerized as follows; 1) The water content of the treated group was significantly decreased comparing with the control group in both 3 and 5 minute occlusion groups. The water content of the 5 minute occlusion group was much increased than that of the 3 minute occlusion group in the control group. 2) The amount of Na and K were significantly increased in the treated group comparing with the control group. 3) The amount of Na, K in relation to water content of the treated group were higher than that of the control group. With the above results, it might be concluded that postischemic brain edema(water content) was more significant in the prolonged occlusion group, and administration of mannitol and betamethasone is effective for the prevention and treated of postischemic brain edema.

Teratoma in the Posterior Cranial Fossa

A rare case of teratoma occuring in the posterior cranial fossa is reported. The tumor was partially encapsulated, and a surgical removal was accomplished. Teratoma is defined as a true tumor, composed of several types of tissues representing more than one germinal layer, which are foreign to the part in which it arises. The literature on teratomas located in the posterior cranial fossa is reviewed.