The subcostal nerve as the target for nerve stimulator guided transverse abdominis plane blocks – A feasibility study

BACKGROUND AND AIMS: Transverse Abdominis Plane (TAP) block was originally described as a landmark-based technique. Peripheral nerve stimulator (PNS) guided blocks are still widely performed, where ultrasound is unavailable. METHODS: Cadaveric dissections were performed which showed the subcostal nerve following a predictable course at the lateral abdominal wall in the TAP. The subcostal nerve was identified by ultrasound in three volunteers. Stimulation of the subcostal nerve was performed using PNS and landmarks as guidance in and 20 patients. Twitches of the anterior abdominal wall muscles were elicited, and needle position and drug dispersion were confirmed using ultrasound. RESULTS: Out of 32 attempts made, the drug dispersion was appropriate in 24, not appropriate on four insertions and twitches were not elicited in 4 attempts. CONCLUSION: Nerve stimulator can be used as a guidance for TAP blocks where the availability of ultrasound is limited.