Cerebrospinal fluid drainage and steroids provide better spinal cord protection during aortic cross-clamping than does either treatment alone

Abstract

We investigated whether intravenous methylprednisolone (30 mg/kg) before 30 minutes of aortic cross-clamping and after 4 hours could enhance the effects of cerebrospinal fluid drainage on spinal cord perfusion pressure and postoperative paraplegia when proximal blood pressure was controlled with sodium nitroprusside and partial exsanguination. Dogs were randomized into three groups: group 1 (n = 6), control; group 2 (n = 7), steroids; and group 3 (n = 6), steroids with cerebrospinal fluid drainage. During aortic cross-clamping, blood pressure proximal to the clamp decreased significantly in each group compared with baseline ( p < 0.05), but did not differ among groups (group 1 = 82.2, group 2 = 82.1, group 3 = 86.6 mm Hg, p > 0.05). Mean distal pressure decreased from systemic values to 8.4, 8.5, and 3.7 mm Hg, respectively, after aortic cross-clamping ( p < 0.05); these values did not differ from one another ( p > 0.05). During aortic cross-clamping, cerebrospinal fluid pressure in groups 1 and 2 did not differ significantly compared with baseline (12.2 versus 8.2, 14.2 versus 10.7 mm Hg, p > 0.05), whereas group 3 the baseline cerebral spinal fluid pressure of 0.7 mm Hg decreased to 0.4 mm Hg ( p < 0.05). Spinal cord perfusion pressure in group 3 was significantly higher than in groups 1 and 2 (3.3 versus −3.9 and −5.7 mm)Hg, p < 0.05), but did not differ between groups 1 and 2, ( p > 0.05). Somatosensory evoked potential loss occurres significantly earlier in groups 1 and 2 than in group 3 (1 minutes 31 seconds and 4 minutes 18 seconds vs 11 minutes 16 seconds, p < 0.05). No significant difference in the time to somatosensory evoked potential loss was noted between groups 1 and 2 ( p > 0.05). Paraplegia rates differed significantly between groups 3 and 1 ( 1 / 6 versus 5 / 6 paralyzed, p < 0.05), but were not different when group 3 was compared with group 2 ( 1 / 6 versus 3 / 7 paralyzed, p > 0.05). This study shows that steroids with cerebrospinal fluid drainage provide spinal cord protection during aortic crossclamping, whereas steroids alone are ineffective.