Anatomical bases of the spread of anesthetic solution in the paravertebral region.

Abstract

An injection of a local anesthetic in the paravertebral region produces an analgesic field on the same side of the body. However, the spread of the anesthetic solution in the endothoracic fascia in the paravertebral region is not clearly elucidated yet. One point in question about the block in this region is whether the local anesthetic spreads from the thoracic to the lumbar level of the paravertebral region. We investigated how the anesthetic fluid traveled to the lumbar paravertebral region. A dye was injected into the paravertebral region in the thoracic cavity of cadavers to study the spread of the anesthetic solution. The dye spread into the abdominal cavity through the medial and lateral arcuate ligaments of the diaphragm while the dye also spread in the chest cavity in the endothoracic fascia posterior to the parietal pleura. In the abdominal cavity, the dye was found to have spread so widely in the transversalis fascia that the subcostal, iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous and femoral nerves, and the celiac ganglion were involved. Although the cadavers were fixed with formalin solution and although there was no blood circulation in the cadavers, the spread of the dye was comparable to the analgesic region produced by anesthetic solution in the human study in previous studies(ref. 3, 4). The functional structure around the vertebral column is yet to be elucidated.