title: 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.
authors.affiliation: Department of Anesthesiology and Pain Medicine, College of Medicine, Yeungnam University, Daegu, Korea.
authors.forename: Gul
authors.initials: G
authors.lastname: Jung
authors.forename: Bum Soo
authors.initials: BS
authors.lastname: Kim
authors.forename: Kyung-Bae
authors.initials: KB
authors.lastname: Shin
authors.forename: Ki-Bum
authors.initials: KB
authors.lastname: Park
authors.forename: Sae Yeon
authors.initials: SY
authors.lastname: Kim
authors.forename: Sun Ok
authors.initials: SO
authors.lastname: Song