[Disturbance of CSF absorption after experimental subarachnoid hemorrhage; correlation with subarachnoid fibrosis]

Correlation between subarachnoid fibrosis and absorption resistance of cerebrospinal fluid (CSF) after experimental subarachnoid hemorrhage (SAH) was studied in dogs. Scanning electron microscope (SEM) was used along with steady-state infusion method. Experimental SAHs were produced by injecting 0.6-1.0 ml/kg of blood into the cisterna magna singly, twice and three times for 11, 7 and 8 dogs respectively. All dogs were sacrificed by perfusing their brain with 10% formaldehyde solution immediately after completion of the measurement of CSF absorption resistance. This was conducted at various periods ranging from 3 to 7 weeks after the first blood injection. Measurement of absorption resistance was performed by infusion of physiological saline solution into the spinal subarachnoid space at speeds of 0.1, 0.2 and 0.3 ml/min for 30, 15 and 10 minutes respectively. The measurement was also conducted in 9 dogs without producing SAH as a control study. Specimens collected from basal cistern, lateral cerebral fissures and parasagittal sulci were observed in their subarachnoid spaces under SEM, and the degree of subarachnoid fibrosis was expressed by one of 5 grades for comparison with the absorption resistance in each dog. The grade of subarachnoid fibrosis significantly correlated with the absorption resistance. The absorption disturbances tended to improve after about a month along with disappearance of subarachnoid fibrosis. The results in this study suggest that subarachnoid fibrosis might be involved in inducing CSF absorption disturbances by affecting both the major and the lesser pathways of CSF.