OP052 Intertransverse process block at the retro-SCTL space: evaluation of injectate spread using MRI and sensory blockade in healthy volunteers

Please confirm that an ethics committee approval has been applied for or granted: Yes: I’m uploading the Ethics Committee Approval as a PDF file with this abstract submission Application for ESRA Abstract Prizes: I apply as a Trainee/Resident/Fellow (no age limit) Background and Aims This study evaluated the spread of injectate and sensory blockade after an ultrasound-guided (USG) intertransverse process block (ITPB) at the retro superior costotransverse ligament (SCTL) space. Methods After ethical approval and informed consent, 10 healthy volunteers received an USG ITPB at the retro-SCTL space (T4-T5 level), using a mixture of 10 ml 0.5% bupivacaine with 0.5 ml gadolinium. At 15 minutes, they underwent a T1-weighted MRI of the thorax. Loss of sensation to cold was assessed at 15 and 60 minutes, and then hourly until 5-hours, after the block. Physical spread of injectate on the MRI and loss of sensation to cold over the thorax were the primary and secondary outcomes, respectively. Results The injectate spread to the ipsilateral paravertebral space, neural foramina, epidural space, sympathetic chain, costotransverse space, intercostal space and erector spinae plane in all volunteers, but the extent of craniocaudal spread was variable (figure 3). Conclusions An ITPB at the retro-SCTL space consistently spreads to the ipsilateral paravertebral space, neural foramina, epidural space, sympathetic chain, costotransverse space, and intercostal space but produces ipsilateral sensory blockade that is variable and wider over the posterior, than anterior, thorax.