Uncovering a new cause of obstructive hydrocephalus following subarachnoid hemorrhage: choroidal artery vasospasm-related ependymal cell degeneration and aqueductal stenosis-first experimental study

Abstract

BACKGROUND: Hydrocephalus is a serious complication of subarachnoid hemorrhage (SAH). Obstruction of the cerebral aqueduct may cause hydrocephalus after SAH. Although various etiologic theories have been put forward, choroidal artery vasospasm-related ependymal desquamation and subependymal basal membrane rupture as mechanisms of aqueductal stenosis have not been suggested in the literature. METHODS: This study was conducted on 26 hybrid rabbits. Five rabbits were placed in a control group, 5 were placed in a sham group, and the remaining rabbits (n = 16) were placed in the SAH group. in the first 2 weeks, 5 animals in the SAH group died. the other 21 animals were decapitated after the 4-week follow-up period. Choroidal artery changes resulting from vasospasm, aqueduct volume, ependymal cell density, and Evans index values of brain ventricles were obtained and compared statistically. RESULTS: Mean aqueduct volume was 1.137 mm(3) +/- 0.096, normal ependymal cell density was 4560/mm(2) +/- 745, and Evans index was 0.32 +/- 0.05 in control animals (n = 5); these values were 1.247 mm(3) +/- 0.112, 3568/mm(2) +/- 612, and 0.34 +/- 0.15 in sham animals (n = 5); 1.676 mm(3) +/- 0.123, 2923/mm(2) +/- 591, and 0.43 +/- 0.09 in animals without aqueductal stenosis (n = 5); and 0.650 mm(3) +/- 0.011, 1234/mm(2) +/- 498, and 0.60 +/- 0.18 in animals with severe aqueductal stenosis (n = 6). the choroidal vasospasm index values were 1.160 +/- 0.040 in the control group, 1.150 +/- 0.175 in the sham group, 1.760 +/- 0.125 in the nonstenotic group, and 2.262 +/- 0.160 in the stenotic group. Aqueduct volumes, ependymal cell densities, Evans index, and choroidal artery vasospasm index values were statistically significantly different between groups (P<0.05). CONCLUSIONS: Ependymal cell desquamation and subependymal basal membrane destruction related to choroidal artery vasospasm may lead to aqueductal stenosis and hydrocephalus after SAH.