Inter-transverse process blocks-clarifications
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TO THE EDITOR: I sincerely thank Dr. Tanaka et al. [1] for responding to my previous letter [2] regarding the inter-transverse process block (ITPB). I wish to provide a few clarifications, feeling obliged to elaborate on the context of my letter and my subsequent evolving understanding of this topic, with the hope that readers will gain a more nuanced understanding of ITPBs.
Firstly, I concur with Tanaka et al. [1] that a costotransverse foramen block (CTFB) was indeed administered in their first case [3]. However, my confusion was not only with the direction of the needle, as stated by Tanaka et al. [1], but with the site of deposition of local anesthetic also. The final needle placement was not at the cranial transverse process (TP) as expected for a CTFB. Instead, the placement landed between the TP and pleura, resembling the needle position of a mid-point transverse process to pleura block (MTPB). Nevertheless, it can still be considered a “CTFB” because the final needle position can be adjusted (slightly deeper and caudad) if the local anesthetic spreads into the erector spinae plane instead of displacing the pleura. I initially overlooked this aspect but later gained clarity [4].
Additionally, the injection sites for local anesthetic are very close in CTFB, MTPB [3], and the subtransverse process interligamentary (STIL) plane block [5]. While the needle trajectory is perpendicular in MTPB, it is directed caudad to cephalad in both CTFB and STIL block. Similarly, the injection site of the costotransverse block – a term I prefer over “multiple‑injection costotransverse block ” for clarity – is also in close proximity to the other three ITPBs (CTFB, MTPB, STIL block). The primary distinction lies in the needle trajectory, proceeding from cephalad to caudad, targeting the neck of the rib attached to the caudad TP [4]. Importantly, clinicians should further investigate which ITPB is easier to perform besides assessing the complications.
Secondly, regarding the “representation of CTFB and MTPB as interfascial plane blocks,” [1], I intended to convey “regional anesthesia techniques” as a broader term rather than specifically focusing on ITPBs. Notably, Kilicaslan et al. [5] also used the term “STIL plane block”. Nevertheless, I should have exercised more precision in my expression.
Last, Tanaka et al. [1] stated that there was “confusion of nerve blocks with similar names and concepts, and that it is clear that procedures of ITPB need to be standardized.” However, I posit that this confusion is exacerbated by the introduction of a plethora of regional techniques in general, not only the ITPBs (thanks to ultrasound application), thus making it difficult to understand the complete nuances of each technique. Moreover, diverse nomenclatures (not "similar names" [1]) contribute to the existing confusion. I suggest that the experts/professional societies in the field of regional anesthesia provide clarifications as and when a new technique is introduced, addressing aspects like novelty, nomenclature, etc. The Editors of concerned journals can also invite experts to share their insights along with the publication of any new regional technique.
Notes
FUNDING
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CONFLICTS OF INTEREST
Raghuraman M Sethuraman is the current editor of Anesthesia and Pain Medicine. However, he was not involved in the peer reviewer selection, evaluation, or decision process of this article.