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BackgroundThis 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.MethodsFifteen 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).ResultsThere 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.ConclusionsThis 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.

Recent reports suggest that ultrasound-guided stellate ganglion block (SGB) is safer and more accurate than classic SGB by the using the surface anatomical landmark. However, previous reports concern the classic paratracheal approach using a small specialized curved probe, which may not be appropriate in some patients. The authors have attempted several approaches, including paratracheal, trans-thyroidal, lateral paracarotid, and lateral approaches, to find a safe and suitable method for real-time ultrasound-guided SGB using a standard high-frequency linear probe. A total of 27 injections were performed on 27 patients with sensorineural hearing loss. The lateral paracarotid out-of-plane and lateral in-plane approaches were identified as the easiest and safest methods among the four tested. In this report, we describe a new lateral paracarotid approach for ultrasound-guided SGB. An ipsilateral paratracheal short-axis transverse scan was acquired at the C6 level with a linear probe (6-13 MHz). The probe was moved laterally, scanning the thyroid, carotid artery, internal jugular vein, longus colli muscle, and the transverse process of the C6, placing the carotid artery in the middle of the view. Light pressure was applied to the probe postero-medially to displace the carotid artery medially and completely compress the internal jugular vein. The needle was inserted out-of-plane between the lateral margin of the carotid artery and Chassaignac's tubercle, traversing the collapsed internal jugular vein, and targeted between the longus colli muscle and the prevertebral fascia. A total of 4 ml of 0.2% ropivacaine was injected for each procedure after a negative aspiration test. Successful blockade was confirmed with the onset of Horner's sign. All 27 injections resulted in successful blockade with Horner's sign presenting within 5 min after injection. Side effects were minor and caused minimal discomfort; they included hoarseness and a foreign body sensation. No hematomas formed after any injections. We suggest that this new lateral paracarotid approach, with out-of plane needle insertion at the C6 tubercle under transverse scan, is a convenient and safe method for performing real-time ultrasound-guided SGB, as it provides a wide, safe space for needle passage without risking thyroid or esophageal injury.

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