Regional anesthesia after spinal cord injury attenuates behavioral loss, hemorrhage, and cell death.

OBJECTIVE

Prior research has shown that regional application of an anesthetic (lidocaine) via a lumbar puncture can attenuate pain-induced secondary tissue loss after spinal cord injury (SCI). Applying lidocaine rostral to injury (at T2) also had a protective effect, suggesting neural signaling to/from rostral systems contributes to pain-induced tissue loss after SCI. The present study examined whether regional anesthesia protects the injured spinal cord when applied immediately after injury in the absence of additional pain. We hypothesized that inhibiting cellular activity in the region of injury would have a protective effect and that increasing the duration of treatment (from 1.5 to 12 h) would amplify this outcome.

METHODS

Male rats received a severe T12 contusion injury and were fitted with a catheter with the tip positioned either at L4 (Experiment 1) or at T2 (Experiment 2). Infusion of a marker at L4 showed dispersion extending to the site of injury. Infusion at T2 was restricted to the upper thoracic region. Regional anesthesia was induced using bupivacaine due to its wide use and long duration of action. Immediately after injury, animals received 30 μL of 0.75% bupivacaine or saline through the implanted catheter. Separate groups then received 0, 1, 3, or 7 additional infusions at 90 min intervals, yielding four treatment conditions: 1.5, 3, 6, or 12 h of local anesthesia. A day after injury, locomotor performance was assessed and a 1 cm region of injured spinal cord was taken to be assayed for markers of hemorrhage, programmed cell death, and inflammation.

RESULTS

Animals that received bupivacaine rostral to injury for 3-12 h exhibited improved locomotor recovery, less hemorrhage, and reduced cell death at the site of injury. Treatment at L4 was less effective in attenuating hemorrhage and cell death. In both experiments, there was no indication that increasing the duration of treatment beyond 3 h had added benefit.

CONCLUSION

The results suggest that local application of an anesthetic at, or rostral to, a SCI may have a protective effect.