Study of Fate of Intracranial Hematoma with Radioactive Isotope Fe<sup>59</sup>

Abstract

There have been several reports on experiments which studied histologically the fate of the blood injected to the brain, subdural space and cisterna magna. The author has produced hematoma by injecting red cells labelled with Fe59 in the cerebrospinal space, the brain, subdural and epidural spaces and under the scalp to clarify the dynamics of absorption. It was found it preliminary experiments that radioactive isotope Fe59 proved to be a very useful tracer to carry out the experiments proper. When it is injected into the ear vein or the cisterna magna of rabbits, Fe59 attached to the red cells leaves the red cells only when they hemolyze, but adheres to new red cells. Most of it becomes distributed in the circulating red cells and hematopoietic tissues and just a small amount of it deposits in the brain. Distribution in the serum and external excretion are also very slight. Deposit in various organs becomes maximum in a short period of time after injection and thereafter maintains a certain value. Fe59 in the circulation only slightly passes into the cerebrospinal space. On the other hand, Fe59 in the cerebrospinal space rapidly passes into the circulation. With increase in amount of intravenous injection of Fe59, higher radioactivities of red cells labelled with Fe59 can be obtained. Consequently, a large amount of Fe59 was injected into the ear vein of normal rabbits, and blood was withdrawn 3 days afterwards. After serum was separated, it was washed by centrifuge and red cells labelled with Fe59 in normal saline were obtained. After this was injected into the cisterna magna, brain, subdural space, epidural space and under the scalp of normal rabbits to produce hematoma, respectively, the appearance of Fe59 in the circulating red cells, serum, CSF and urine was studied periodically. In the case of hematoma in the cisterna magna, the passage of Fe59 into the circulation by hemolysis and absorption was fastest, while the deposit in the injected tissues were least. In this case, red cells in the cisterna magna rapidly disappear. This may be due to dilution with the cerebrospinal fluid. In the case of hematoma in the brain, the passage into circulation due to hemolysis and. absorption was less than that in the case of hematoma in the cisterna magna. The deposit in the injected tissue was smaller than that in the case of hematoma under the scalp and epidural hematoma. Absorption into the circulation through CSF was recognized. In the case of subdural hematoma, the passage and absorption into the circulation by hemolysis were less fast than those in the cases of hematoma in the cisterna magna and intracerebral hematoma. Deposit in the injected tissues was less than that in hematoma in the cisterna magna. Passage into the cerebrospinal space was recognized. In the case of epidural hematoma, the passage into the circulation by hemolysis and absorption was most delayed, while the deposit in the injected tissues was the most among the intracranial hematomas. In this case, no absorption into the cerebrospinal space was noticed. In the case of hematoma under the scalp, when compared with various intracranial hematomas, the passage into blood due to hemolysis and absorption was most prolonged, while the deposit into injected tissue was the most. In this case, absorption into the cerebrospinal space was not recognized.