Minimal Concentration of Lidocaine for a Diagnostic Stellate Ganglion Block

Chang, Ju Hyun; Song, Sun Ok

Abstract

BACKGROUND
The aim of this study was to determine an adequate minimal concentration of lidocaine in a stellate ganglion block for decreasing a false positive response to a diagnostic sympathetic blockade determining whether the patient's pain is SMP or SIP.
METHODS
This crossover study was performed in twenty patients with sudden sensory neural hearing loss. All patients received three times SGB using three different concentrations (1%, 0.5% and 0.25%) of 8 ml lidocaine at the sixth cervical vertebral level via an anterior paratracheal approach. The blocks were separately done at one week intervals in random order. The occurrence, onset time and action duration of Horner's syndrome were observed after each SGB.
RESULTS
Positive cranial sympathetic blockade (Horner' syndrome) was present in all patients using 1% and 0.5% lidocaine. It was present in 60% of the patients using 0.25% lidocaine. Onset time was not significantly different among the three groups. Action duration of 1% and 0.5% lidocaine groups was significantly longer than the 0.25% lidocaine group. There was no critical side effects, and temporary foreign body sensation was the most common side effect.
CONCLUSIONS
The results of this study suggest that 0.5% lidocaine is an adequate minimal concentration for diagnostic SGB. Therefore, we recommend that 0.5% lidocaine instead 1% should be used in diagnostic SGB to decrease a false positive response to a sympathetic blockade.