Motor blockade during epidural anesthesia

The effects of lumbar epidural anesthesia (LEA) on a previously described test of function of the rectus abdominalis muscle (the RAM-test) were compared with the effects of LEA on the Bromage test of muscle power in the hips and legs in 20 women having elective cesarean sections under LEA using 0.5% bupivacaine with epinephrine 1:200,000. The results showed no statistically significant correlation between the two tests. We conclude that zones of differential somatic motor blockade are present during LEA and that in obstetrics the RAM-test is the more appropriate test for evaluating the effects of LEA on somatic motor function. Use of the RAM-test is suggested in situations where one is interested in motor function of the abdominal wall muscles under LEA.