Intertransverse process block (ITPB) at the retro-superior costotransverse ligament (retro-SCTL) space: Evaluation of local anesthetic spread using MRI and sensory blockade in healthy volunteers

Pawinee Pangthipampai; Palanan Siriwanarangsun; Jatuporn Pakpirom; Ranjith Kumar Sivakumar; Manoj Kumar Karmakar

doi:10.1016/j.jclinane.2024.111718

Intertransverse process block (ITPB) at the retro-superior costotransverse ligament (retro-SCTL) space: Evaluation of local anesthetic spread using MRI and sensory blockade in healthy volunteers

J Clin Anesth. 2024 Dec 18:101:111718. doi: 10.1016/j.jclinane.2024.111718. Online ahead of print.

Authors

Pawinee Pangthipampai¹, Palanan Siriwanarangsun², Jatuporn Pakpirom³, Ranjith Kumar Sivakumar⁴, Manoj Kumar Karmakar⁵

Affiliations

¹ Department of Anesthesiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
² Department of Radiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
³ Department of Anesthesiology, Faculty of Medicine, Prince of Songkla University, Hat Yai, Thailand.
⁴ Department of Anesthesia and Intensive Care, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China.
⁵ Department of Anesthesia and Intensive Care, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. Electronic address: karmakar@cuhk.edu.hk.

PMID: 39700657
DOI: 10.1016/j.jclinane.2024.111718

Abstract

Background: This study evaluated the spread of a local anesthetic, using MRI and sensory blockade, after an intertransverse process block (ITPB) at the medial aspect of the retro-superior costotransverse ligament (retro-SCTL) space - the medial retro-SCTL space block.

Methods: Ten healthy volunteers received a single-injection ultrasound-guided medial retro-SCTL space block at the T4-T5 level using a mixture of 10 ml 0.5 % bupivacaine with 0.5 ml gadolinium. At 15 min, they underwent a high resolution, fat suppressed, T1 weighted MRI scan of the cervicothoracic spine. Loss of sensation to cold was assessed at 15 and 60 min, and then hourly for 5-h, after the block.

Results: MRI showed consistent (100 %) spread of local anesthetic to the intercostal and paravertebral spaces, anterolateral aspect of the vertebral body (sympathetic chain), costotransverse space, neural foramina, and epidural space in all participants. However, sensory blockade was variable across the ipsilateral hemithorax. Hypoesthesia was more common than anesthesia in both the anterior (median [IQR], 3.5 [2-5] vs 0 [0-1.25], p < 0.001) and posterior (median [IQR], 6[3-7] vs 2[1-3], p < 0.001) hemithorax. Additionally, more dermatomes exhibited anesthesia in the posterior compared to the anterior hemithorax (median [IQR], 2[1-3] vs 0[0-1.25], p = 0.01). A variable number of contralateral dermatomes were also affected in 3 (30 %) volunteers. There was no statistically significant correlation between the local anesthetic spread and the number of hypoesthetic (r = 0.53, p = 0.11) or anesthetic (r = 0.09, p = 0.78) dermatomes on the ipsilateral hemithorax.

Conclusions: A single-injection medial retro-SCTL space block, at the T4-T5 level with 10.5 ml of local anesthetic, consistently spreads to the ipsilateral intercostal and paravertebral spaces, sympathetic chain, costotransverse space, neural foramina and epidural space, but produces ipsilateral sensory blockade that is variable and wider over the posterior than anterior hemithorax.

Keywords: Analgesia; Anesthesia; Healthy volunteers; Intertransverse process block; MRI; Retro-SCTL space; Thoracic paraspinal block.