A new anterior approach to the sciatic nerve block.
BACKGROUND
Although several anterior approaches to sciatic nerve block have been described, they are used infrequently. The authors describe a new anterior approach that allows access to the sciatic nerve with the patient in the supine position.


METHODS
Sciatic nerve blocks were performed in 22 patients. A line was drawn between the inferior border of the anterosuperior iliac spine and the superior angle of the pubic symphysis tubercle. Next, a perpendicular line bisecting the initial line was drawn and extended 8 cm caudad. The needle was inserted perpendicularly to the skin, and the sciatic nerve was identified at a depth of 10.5 cm (9.5-13.5 cm; median and range) using a nerve stimulator and a 15-cm b-beveled insulated needle. After appropriate localization, either 30 ml mepivacaine, 1.5% (group 1 = knee arthroscopy; n = 16), or 15 ml mepivacaine, 1.5%, plus 15 ml ropivacaine, 0.75%, (group 2 = other procedures; n = 6) was injected.


RESULTS
Appropriate landmarks were determined within 1.3 min (0.5-2.0 min). The sciatic nerve was identified in all patients within 2.5 min (1.2-5 min), starting from the beginning of the appropriate landmark determination to the stimulation of its common peroneal nerve component in 13 cases and its tibial nerve component in 9 cases. A complete sensory block in the distribution of both the common peroneal nerve component and the tibial nerve component was obtained within 15 min (5-30 min). A shorter onset was observed in patients who received mepivacaine alone compared with those who received a mixture of mepivacaine plus ropivacaine (10 min [5-25 min] vs. 20 min [10-30 min]; P < 0.05). Recovery time was 4.6 h (2.5-5.5 h) after mepivacaine administration. The addition of ropivacaine produced a block of a much longer duration 13.8 h (5.2-23.6 h); P < 0.05. No complications were observed.


CONCLUSIONS
This approach represents an easy and reliable anterior technique for performing sciatic nerve blocks.
Chelly
J E
JE
Department of Anesthesiology, The University of Texas Medical School-Houston, 77030-1503, USA. jchelly@anes1.med.uth.tmc.edu
Delaunay
L
L
D000328:Adult; D000368:Aged; D000577:Amides; D000779:Anesthetics, Local; D001182:Arthroscopy; D005260:Female; D006801:Humans; D007717:Knee / Q000601:surgery; D007866:Leg / Q000601:surgery; D008297:Male; D008619:Mepivacaine; D008875:Middle Aged; D008991:Monitoring, Physiologic; D009407:Nerve Block / Q000379:methods*; D010147:Pain Measurement; D000077212:Ropivacaine; D012584:Sciatic Nerve / Q000033:anatomy & histology / Q000187:drug effects*; D016683:Supine Position
D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D008619:Mepivacaine