Experimental study of cerebral vasospasm

1991 Fiscal Year Final Research Report Summary

• Project/Area Number: 01570823
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Cerebral neurosurgery
• Research Institution: Osaka Medical College
• Principal Investigator: OHTA Tomio Osaka Medical College Professor, 医学部, 教授 (80025650)
• Co-Investigator(Kenkyū-buntansha): NAGANO Yuuzou Osaka Medical College Assistant, 医学部, 助手 (30208037) ; YAMADA Kyouzou Osaka Medical College Lecturer, 医学部, 講師 (80200715) ; MIYAKE Hiroji Osaka Medical College Lecturer, 医学部, 講師 (50181996) ; YAMAMOTO Masato Osaka Medical College Lecturer, 医学部, 講師 (20158306) ; SHIGUMA Michio Osaka Medical College Lecturer, 医学部, 講師 (90154195)
• Project Period (FY): 1989 – 1991
• Keywords: Subarachnoid hemorrhage / Cerebral vasospasm / Cerebral blood flow / Double injection method

Research Abstract

Because it is difficult to exactly estimate cerebral hemodynamics after subarachnoid hemorrhage (SAH) in clinical cases, cerebral blood flow (CBF), epidural pressure (EDP) and mean arterial blood pressure (MABP) were measured continuously during the acute stage after the induction of experimental SAH in rats. SAH was induced by a cisternal injection of 0.3 ml of autologous arterial blood. However, the patterns of chronological changes in CBF and EDP varied greatly, and could be classified into 3 types. The clot distribution in the basal cistern could also be classified into 3 types which were associated with the respective patterns of CBF and EDP changes. These results depend on the variation of the clot distribution in relation to the morphological difference of the subarachnoid space. Therefore, cerebral hemodynamics after SAH is most affected by the changes of the intracranial cranial pressure (ICP). It is important to rapidly decrease ICP in severe SAH.
On the other hand, the amount of blood in the subarachnoid space is an important factor in the pathogenesis of cerebral vasospasm. We used the double injection method in rats to infuse autologous blood as much as possible. Cerebral vasospasms that cause delayed ischemic neurological deficits in humans indicate intimal thickening and corrugation of internal elastica lamina. But light photomicrographic findings of the cerebral arteries of rats subjected to double injections failed to demonstrate any morphological changes similar to those observed in vasospasm in human subjects or mammalian models. Our studies indicate that the rat SAH model has limited applicability to the study of the delayed cerebral vasospasm.