The central nervous system pressure histogram in hydrocephalus and hydromyelia

Association between subarachnoid hemorrhage-induced hydrocephalus and hydromyelia: pathophysiological changes developed in an experimental model

BACKGROUND

Subarachnoid hemorrhage-induced hydrocephalus (SAIH) can affect the prognosis of subarachnoid hemorrhage (SAH). The relationship between hydromyelia and SAIH has been rarely investigated. This experimental model aimed to identify the pathophysiological changes developed in the SAH and elucidate the relationship between hydromyelia and SAIH.

MATERIAL AND METHODS

25 female rabbits were randomly divided into three groups. The SAH group (n = 15), sham group (n = 5), and control group (n = 5). In the former group, the injection of 0.5 mL/kg of autologous blood was carried out into the cisterna magna on days 0 and 2. All animals were decapitated 21 days thereafter. Histological examinations of the medulla spinalis and brain samples were performed.

RESULTS

The mean volumes of the central channel were 1.054, 1.287, and 1.776 mm³ in the control, sham, and SAH groups, respectively (p = 0.028). The mean normal ependymal cell densities were 4.210, 3.602, and 2.923 cells/mm² in the control, sham, and SAH groups, respectively (p = 0.002). The mean ventricular Evans' indices were 0.31, 0.34, and 0.41, in the control, sham, and SAH groups, respectively (p = 0.006). Basement membrane rupture, desquamated ependymal cells, and central channel occlusion were observed on histological examinations of the SAH group.

CONCLUSIONS

Subependymal basement membrane destruction, blood cell accumulation on it, ependymal cell desquamation, increased cerebrospinal fluid (CSF) secretion, and increased ICP in the central channel that causes hydromyelia. When these pathological changes are chronically apparent, they may reflect on CSF pathways and cause permanent SAIH. Preventing long-time SAH-induced hydromyelia is believed to reduce the high rate of treatment-requiring SAIH.

Correlation of hydromyelia with subarachnoid hemorrhage-related hydrocephalus: an experimental study

Although the central canal is an integral component of the cerebral ventricular system, central canal dilation has not been examined adequately during the progression of subarachnoid hemorrhage-related hydrocephalus (SAH-H). Central canal dilation-associated ependymal cell desquamation or subependymal membrane rupture has been rarely reported. Herein, we try to describe possible mechanisms of central canal dilation "Hydromyelia," developing after SAH. A total of 25 New Zealand hybrid female rabbits were recruited. Five served as controls, and five received sham operations. In the remaining animals (n = 15), 0.5 mL/kg of autologous blood was injected into the cisterna magna twice on 0 and 2nd days. Five of these animals died within a few days. A total of 10 survivor animals decapitated 3 weeks later, and the brains and cervical spinal cords were histologically examined. Central canal volumes, ependymal cell numbers on the canal surfaces, and the Evans' indices of the ventricles were compared. On histological examination, central canal occlusion with desquamated ependymal cells and basement membrane rupture were evident. The mean Evans' index of the brain ventricles was 0.31, the mean central canal volume was 1.054 mm³, and the normal ependymal cell density was 4.210/mm² in control animals; the respective values were 0.34, 1.287 mm³, and 3.602/mm² for sham-operated animals, and 0.41, 1.776 mm³, and 2.923/mm² in the study group. The differences were statistically significant (p < 0.05). Hydromyelia, an ignored complication of SAH-H, features ependymal cell desquamation, subependymal basement membrane destruction, blood cell accumulation on the subependymal cell basement membrane, and increased CSF pressure. Hydromyelia may be a significant complication following SAH.