Recto-intercostal fascial plane block for upper abdominal analgesia: the ultimate solution?

Dear Editor,

We read with great interest the article by Ökmen et al. [1], who evaluated interfascial plane block techniques for analgesia following upper abdominal surgery. The authors reported that the external oblique and rectus abdominis (EXORA) plane block was not inferior to the modified thoracoabdominal nerve block through perichondrial approach (M-TAPA) in providing effective analgesia to the upper abdominal wall.

The innervation of the upper abdominal wall by the thoracoabdominal nerves is complex. Several techniques have been described for cutaneous blockade in both the mid and lateral upper abdominal regions, including the recently introduced EXORA plane block and deep rectus sheath block (also known as anterior transversalis fascia block) [2,3]. Additionally, the serratus intercostal plane block (or modified blocking the branches of intercostal nerves in the midaxillary line [BRILMA] block), TAPA and M-TAPA, oblique subcostal transversus abdominis plane block, external oblique plane block (and new derivatives), and even the erector spinae plane block also aim to cover this region.

The lateral cutaneous branches of the 6th–9th thoracoabdominal nerves become superficial by piercing the intercostal and serratus anterior muscles around the midaxillary line and provide innervation to the lateral abdominal wall. The cutaneous branches of the 9th–11th thoracoabdominal nerves become superficial by piercing the external oblique muscle around the same line and participate in the innervation of the same region. Blockade techniques are named according to the muscle above the injection point, such as external oblique and serratus intercostal. However, this is actually the fascia that covers the costal margins along the length of the rib cage and runs deep into the rectus abdominis muscle anteriorly. For example, the deep and superficial fascias of the external oblique muscle come together to form the anterior part of the rectus sheath. What runs under the rectus abdominis muscle and covers the 5th–8th costal cartilages? Moreover, how can we explain the mechanism of cutaneous blockade in the mid abdomen achieved by the external oblique plane, EXORA, or BRILMA blocks?

The rectointercostal fascial plane block, a technique we have recently described, involves administering a local anesthetic between the 6th–7th costal cartilages and rectus abdominis muscle. In our cadaveric study, when we administered a high volume of methylene blue (30 ml), it spread extensively from the sternum and mid abdomen to the midaxillary line [4]. In the external oblique plane and modified BRILMA blocks, the local anesthetic is expected to spread through the same pathway; however, it is possible that it is potentially restricted from spreading medially by the transformation of the fascia of the external oblique muscle into the aponeurosis. This seems to be overcome with the EXORA plane block by pushing the needle deep into the rectus abdominis muscle. In fact, despite the 4–5 cm difference in the injection points of the EXORA and rectointercostal blocks, they appear to be in the same or a very similar plane. Anatomically, the name rectointercostal block seems more appropriate because the nomenclature of fascial plane blocks should be based on the interfascial plane where the needle tip is aimed, not the potential spread area of the local anesthetic [5].

In our clinic, we employed the rectointercostal block in addition to the rectus sheath block for analgesia in surgical procedures performed through mid-abdominal incisions extending to the xiphoid. We found that this combination provided effective analgesia in both the mid and lateral abdominal regions, including drainage tubes in the lateral abdomen, which was beyond what was expected from the rectus sheath block. Thus, the journey of regional anesthesia from central neuraxial to peripheral techniques may be nearing its end, with the rectointercostal block possibly being the most effective approach. Certainly, this hypothesis should be validated through extensive clinical studies and skin mapping analyses to draw more definitive conclusions. Fig. 1 illustrates this hypothesis.

Fig. 1.

Demonstration of the oblique transverse anatomy in the thoracoabdominal transition region. (A) Normal anatomy. (B) Serratus intercostal plane block or modified BRILMA. (C) External oblique intercostal plane block. (D) Rectointercostal block. SAM: serratus anterior muscle, EOM: external oblique muscle, RAM: rectus abdominis muscle, Cc: costal cartilage. The independent lines around each muscle in the same color as the muscle represent the superficial and deep fascias of the respective muscle. The blue dye indicates the possible distribution of the local anesthetic. The return of the external intercostal muscle to its aponeurosis in the parasternal area is shown by thinning of the line.