The optimal volume of 0.2% ropivacaine required for an ultrasound-guided stellate ganglion block

Abstract

Background: This study was performed to find the optimal volume of local anesthetics needed for a successful ultrasound-guided stellate ganglion block (SGB) to treat head and neck pathology.

Methods: Fifteen female and fourteen male sensory-neural hearing loss patients received 4 times SGBs with 0.2% ropivacaine in volumes of 6, 4, 3 and 2 ml at 1 to 3 day intervals. Using the transverse short-axis view of the neck that showed Chassaignac's tubercle at the C6 level, a 25-gauge, and 4 cm needle was inserted via the lateral paracarotid approach with out-of-plane targeting between the prevertebral fascia and the ventral surface of longus colli muscle (subfascial injection). A successful block was confirmed with the onset of ptosis (Horner's syndrome).

Results: There were no significant statistical differences between the presence of Horner's syndrome and the volume of local anesthetics given. However, Horner's syndrome was present in all trials for the 4 ml and 6 ml groups. Six (20.7%) and three out (10.4%) of twenty-nine trials in the 2 ml and 3 ml groups, respectively, failed to elicit Horner's syndrome. The duration of action was significantly different in the 2 ml group compared to that of the 6 ml group, but there was no significant difference between the other groups, including the 4 ml vs. 6 ml groups. The side effects were not different between the groups.

Conclusions: This data suggests that the optimal volume of 0.2% ropivacaine for ultrasound-guided SGB to treat the head and neck pathology in daily practice is 4 ml.

Keywords: Local anesthetics; Stellate ganglion block; Ultrasound; Volume.

Fig. 1

Sonoanatomy for an ultrasound-guided SGB: the transverse short-axis view at the C6 level. CA: carotid artery, IJV: internal jugular vein (in a partially compressed state by the probe), PVF: prevertebral fascia, LCo: longus colli muscle, SCM: sternocleidomastoid muscle, Thy: thyroid gland, T: Chassaignac's tubercle, med: medial, lat : lateral.

Fig. 2

Ultrasound image of the C6 transverse short-axis view following left SGB at the C6 level. Arrows show the subfascial spread of local anesthetics above the longus colli muscle. The fine long arrow indicates the out-of-plane needle path. CA: carotid artery, LCo: longus colli muscle, SCM: sternocleidomastoid muscle, Thy: thyroid gland, T: Chassaignac's tubercle, med: medial, lat: lateral.