Transversalis fascia plane block, a novel ultrasound-guided abdominal wall nerve block
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KeywordsIliac Crest Transversus Abdominis Plane Transversus Abdominis Plane Block Transversus Abdominis Transversalis Fascia
To the Editor,
The lateral cutaneous branches (LCB) of the thoraco-abdominal nerves (T6 to L1) arise proximal to the angle of the rib, run a short distance with the main nerve, and emerge obliquely through the overlying muscles in the midaxillary line.1 They pass superficially to supply the skin of the lateral thorax, the abdomen, the iliac crest, and the upper thigh as far as the greater trochanter of the femur. As previously described, it is rare to produce block of the LCB of the subcostal (T12) and iliohypogastric (L1) nerves when performing ultrasound-guided posterior transversus abdominis plane (TAP) block.2 The subcostal and iliohypogastric nerves normally send out their LCB preceding entry or very proximal in the TAP. The LCB leave the TAP in a more posterior position than the local anesthetic of the ultrasound-guided posterior TAP block, which appears on imaging as being restricted from spreading posterior to the extent of the muscle belly. The subcostal and iliohypogastric nerves pass deep over the anterior surface of the quadratus lumborum muscle, which extends from the 12th rib to the iliac crest. The subcostal nerve then continues a short distance deep to the aponeurotic posterior extension of the transversus abdominis muscle before passing through the aponeurosis into the TAP.3 The iliohypogastric nerve continues deep to the transversus muscle aponeurosis and belly to penetrate the transversus in a more anterior and highly variable position.4
Local anesthetic injected between the transversus abdominis muscle and its deep investing transversalis fascia will spread over the inner surface of the quadratus lumborum muscle and block the proximal portions of the T12 and L1 nerves. This will produce block of both the anterior and the lateral branches of these nerves. This transversalis fascia block (TFP) targets these nerves anatomically between the lumbar plexus block and the TAP block.
To date, this novel TFP block has been used clinically for long-lasting analgesia in 17 patients, including five cases of iliac crest bone harvest. Other operations have included appendicectomy, cecostomy, and inguinal hernia repair, often in combination with TAP block on needle withdrawal. Early in the experience, one patient underwent a repeat block due to postoperative pain after iliac crest bone harvest, no detectable block, and a difficult block owing to the depth of imaging. The patient’s pain was relieved by the second block. The other 16 patients had a detectable block to ice over the iliac crest; four of these were for bone graft harvest with excellent analgesia. There have been no complications. Compared with the more anteriorly placed ultrasound-guided posterior TAP injection, the block is limited in the anterior abdomen, as only L1, T12, and possibly T11 will be blocked. However, T12 and L1 supply laterally over the iliac crest as far as the greater trochanter enabling a simple and effective analgesic block over the iliac crest, upper lateral thigh, and lower abdomen. Also, the TFP is continuous medially with the plane of the lumbar plexus, and opening the plane with fluid may provide an alternative lateral approach to lumbar plexus block under ultrasound-guidance.
Conflicts of interest
- 1.Davies F, Gladstone RJ, Stibbe EP. The anatomy of the intercostal nerves. J Anat 1931; 66: 323–33.Google Scholar