[Diabetes insipidus following the rupture of cerebral aneurysms--with special reference to preoperative cases].

The authors reported 4 cases with preoperative diabetes insipidus (DI) following the rupture of cerebral aneurysms. In addition, the incidence of preoperative DI and the mechanisms as the cause of DI in cases with the ruptured cerebral aneurysms were also discussed. In the 114 cases underwent clipping of the ruptured cerebral aneurysms more than 14 days after the bleed, only 4 cases (3.5%) developed DI preoperatively. The time period between last subarachnoid hemorrhage and the onset of DI ranged from 23 to 35 days. This delayed onset of DI after subarachnoid hemorrhage was different from previous reports. A few of mechanisms had been suggested through which DI could be brought about in cases with cerebral aneurysm. That is; direct compression to the hypothalamo-hypophysial system by a giant aneurysm. compression and destruction of the hypothalamus by a hematoma or hemorrhage, ischemic changes in the hypothalamo-hypophysial system caused by vasospasm. In the present 4 cases, no had giant aneurysms. Although CT scan revealed subarachnoid clot in all cases, it did not show apparent hypothalamic lesion except case 1 who had small hematoma in the region of the basal frontal interhemispheric fissure. Symptomatic vasospasm was recognized in 3 cases. However, one of them had mild vasospasm restricting in M1 portion and case 3 was free of any vasospasm. Furthermore, the time period from the identification of vasospasm until the onset of DI ranged from 2 to 3 weeks. These results suggest that another mechanism in addition to a hemorrhage, hematoma and/or vasospasm may exist.(ABSTRACT TRUNCATED AT 250 WORDS)