Spinal Cord Blood Flow in Experimental Transient Traumatic Paraplegia

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Abstract
Blood flow in the lateral funiculus of the thoracic spinal cord was measured in 24 anesthetized cats using the H2 clearance method. In a control series of 8 nontraumatized animals, blood flow measurements were taken from the T[thoracic]-5 and T-6 segments for 6 consecutive hours. The mean spinal cord blood flow (SCBF) in the control group was 12.8 .+-. 3.51 (SD) ml/min per 100 g on the basis of 107 measurements over 6 h. In the experimental groups, 16 animals were similarly prepared. The spinal cords of these animals were then traumatized by dropping a 20 g weight 5 cm (100 g-cm trauma) or 13 cm (260 g-cm trauma) onto the T-5 segment. Previous experiments showed that these trauma levels lead to a transient paraplegia of < 10 and 30 days'' duration, respectively. Blood flow measurements [200] from T-5 and T-6 were taken over the 6 h following trauma. In the 7 animals of the 100 g-cm group, mean SCBF after trauma from the T-5 segment was 12.6 .+-. 3.45 (SD) ml/min per 100 gm on the basis of 50 measurements taken over 6 h; not significantly different from the controls (P > 0.70). In the 260 g-cm group, mean SCBF from T-5 for 6 h after trauma was 17.3 .+-. 6.60 (SD) ml/min per 100 gm; significantly higher than controls (P < 0.001). Mean SCBF 3 to 6 h after trauma was significantly elevated over controls (P < 0.05). The mean hyperemia in the 260 g-cm group was due to marked hyperemia in only 4 animals of the series, while 5 animals maintained blood flows in the normal range. This experiment provides quantitative evidence that white matter ischemia does not occur in spinal cord injuries that can be expected to produce only transient paraplegia. White matter ischemia in the acute phase of severe spinal cord trauma may be related to secondary injury and subsequent permanent paraplegia.