Computerized axial tomography to define the distribution of solution after stellate ganglion nerve block.

STUDY OBJECTIVE: To define the spread of local anesthetic after C6 stellate ganglion nerve block using computerized axial tomography (CAT).

DESIGN: Prospective, open descriptive study.

SETTING: Outpatient pain consult center.

PATIENTS: 10 ASA status I patients undergoing stellate ganglion nerve blocks for sympathetically maintained pain.

INTERVENTIONS: Radiocontrast and local anesthetic was given in 5 ml increments to 20 ml total volume for C6 stellate ganglion nerve blocks in eight patients and C7 in two patients.

MEASUREMENTS AND MAIN RESULTS: CAT scanning was performed at baseline and after 5, 10, 15, and 20 ml of injectate was administered. Cervical level and pattern of injectate spread was recorded after each increment. Neck pressure above C6 did not promote caudal spread. One half of the injections were beneath prevertebral fascia. Injections on top of the fascia spread more diffusely around C6. All injections in high volume reached the medial aspect of T1 around the head, not neck, of the first rib.

CONCLUSIONS: Solutions injected for C6 stellate ganglion nerve block concentrate medial to the stellate ganglion at T1. Thus, they must produce upper extremity sympathectomy by a mechanism other than contact with the ganglion.