Background and Aims The cervical plexus block (CPB) is used in a variety of head and neck surgeries providing efficient anesthesia and analgesia. It can be divided into superficial (above superficial fascia of the neck), intermediate (between superficial and prevertebral fascia) and deep (below prevertebral fascia) CPB. We studied the postoperative analgesic efficacy of intermediate CPB on thyroid surgery and the degree of phrenic nerve blockade caused by the block.

Methods 14 patients scheduled for thyroid surgery were randomized into two groups of 7; Group A received bilateral intermediate CPB using 15 ml ropivacaine 0.375% along with paracetamol and dexketoprofen upon patient’s demand, for postoperative analgesia. Group B received the same painkillers without CPB. The primary outcome of our study was diaphragmatic excursion on the right side, preoperatively and immediately postoperatively, measured ultrasonographically by a POCUS experienced anesthesiologist during forced inspiration. We additionally measured diaphragmatic thickening fraction as long as time for first analgesic demand and pain scores (NRS) in 6 and 24 hours postoperatively.

Results Postoperatively the diaphragmatic excursion decreased in both groups, but it decreased more in Group A (46 ±6mm vs 48 ± 5mm), nevertheless statistically and clinically insignificantly (p>0.05). Thickening fraction was > 25% in all instances. In group A, we observed longer time for first analgesic demand postoperatively and lower pain scores in all instances.

Conclusions Intermediate CPB can be an effective and safe method for postoperative pain control in thyroid surgery. Diaphragmatic dysfunction due to the block seems to be insignificant, but larger studies are needed to confirm this observation.