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Addition of a stellate ganglion block (SGB) to a cervical paravertebral block (CPVB) during arthroscopic shoulder surgery may not result in improved analgesia, according to a prospective double-blind randomized controlled trial published in Pain Medicine.
A total of 20 adult patients who were scheduled to undergo arthroscopy for non-chronic shoulder disease and non-fractured shoulders were randomly assigned to receive single CPVB (5 mL of levobupivacaine 0.5%; n=10) or CPVB plus SGB (5 mL and 3 mL of levobupivacaine 0.5%, respectively, n=10).
Thermal quantitative sensory testing (QST) was performed on the C4 through C7 dermatomes prior to and 0.5, 6, 10, and 24 hours after local anesthetic infiltration to detect thresholds for cold/heat pain and cold/warm sensations.
The time course of QST thresholds for the neurosensitive/nociceptive modalities assessed was the primary outcome. The degree of motor block and time to administration of rescue analgesics were the study’s secondary and tertiary outcomes, respectively.
No differences were observed between the 2 groups for detection thresholds for the motor block, neurosensitive/nociceptive modalities, visual analogue scale scores, or timing for rescue analgesics.
Participants in the combined therapy group, but not those receiving CPVB only, had signs of Horner syndrome. Further research in a larger patient population may be required to determine the applicability of these findings in the clinical setting.
As the SGB did not improve analgesia obtained with CPVB during shoulder arthroscopy in this study, the investigators stated, “It is … not unreasonable to suppose that pain from soft tissue injuries without bony lesions is transmitted mainly by somatic nerves with no or only minimal involvement of the sympathetic nervous system.”
Reference
Sermeus LA, Vanlinthout LE, Hans GH, et al. Effects of stellate ganglion block on analgesia produced by cervical paravertebral block as established by quantitative sensory testing: a randomized controlled trial [published online February 2, 2018]. Pain Med. doi: 10.1093/pm/pny004
