A Study of Correlation between Epidural and CSF Pressure

Choi, Kyung Don; Cheun, Jae Kyu

Abstract

A continuous leakage in association with hypovolemia and hypotention of the cerebrospinal fluid is the primary cause of a post-spinal headache. The spinal blood patch is known to be the best choice of treatment for a severe postspinal headache, and measurements of cerebrospinal fluid pressure with saline injection into the lumbar spinal space have been reported. However, a dynamic correlation of the pressure change between epidural and CSF pressure after the epidural injection of the volume has not been known. This study was primarily carried out to investigate dynamic changes and the correlation between epidural and CSF pressure with and without epidural volume injection so that it would be helpful to understand the mechanism as to the immediate and permanent cure, and recurrence of post-spinal headache. Twenty cases were divided into two groups: Group I (control): Normal CSF and epidural pressure were measurd in a sitting position (10 cases) and in a lateral position (10 cases). Group II: CSF and epidural pressure after the injection of 2% lidocaine 10 ml were measured in a sitting position (10 cases) and in a lateral position (10 cases). The differences between CSF and epidural pressure from groups I and II were calculated. The rusults were as follows. CSF pressure: The mean Mean opening pressure was 37.3+/-4.2 cm H2O, mean pressure after injeciton was 41.3+/-6.1 cm H2O and pressure rise was 4 cm H2O (10.7%) in the sitting position, and the mean opening pressure was 9.3+/-3.8 cm H2O mean pressure after injection was 13.9+/-5.2 cm H2O and pressure rise was 4.6 cm H2O (49.5%) in the lateral position. Epidural pressure: The mean initial pressure was 5.82.6 cm H2O, mean pressure after injection was 16.9+/-12.4 cm H2O and pressure rise was 22.7 cm H2O (391.3%) in the sitting posittion, and mean initial pressure was 6.1+4.0 cm H2O, mean pressure after injection was 9.5+ 7.9 cm H2O, and pressure rise was 15.6 cm H2O (255.7%) in the lateral position. Difference between CSF and epidural pressure (CSF pressure-epidural pressure, cm H2O): The mean pressure difference in the control group was 43.1+5.7 cm H2O and mean pressure difference after injection was 24,4+/-12.4 cm H2O in sitting position, and mean pressure difference in the control group was 15.4+/-4.1 cm H2O and mean pressure difference after injection was 4.4+/-10.1 cm H2O in lateral position. It is obvious that the injection of 10 ml of 2% lidocaine reduced the pressure difference greatly between the subarachnoid and epidural spaces. These results indicate that the volume of 10 ml is suitable for an epidural blood patch and it suggests that the patient must be placed in a supine or lateral position immediately after an epidural blood patch is done because of the equalizing of the pressure difference. However, there was still a small difference in pressure between the two compartments: The CSF pressure being higher than the epidural pressure.