The high thoracic sympathetic nerve system--its anatomic variability.

Upon studying microscopically and macroscopically 18 resection preparations of upper thoracic sympathectomies it is clear that the variability in the anatomy of the sympathetic nervous system in connection with the spinal nervous system is higher than has always been described. A fine network of smaller and larger nerve bundles was found which connect the sympathetic and spinal nerve systems. Light microscopical perikarya were identified in many nerve bundles. These findings have an important impact on the concept of the effectiveness of thoracic sympathectomy.