The key to success in blocking lateral cutaneous branches with re-modified thoracoabdominal nerves block through perichondrial approach: a newly discovered space between the endothoracic fascia, diaphragm, and costodiaphragmatic recess

This study aimed to determine whether the administration of a modified thoracoabdominal nerves block through perichondrial approach (M-TAPA) could result in the blockade of the lateral cutaneous branches. This study focused on a newly discovered anatomical space/plane adjacent to the M-TAPA plane, which we termed “space between the endothoracic fascia, diaphragm, and costodiaphragmatic recess: SEDIC.”

Thirteen sides of nine formalin-embalmed cadavers were macroscopically dissected to investigate the anatomical spaces related to the effects of M-TAPA. Furthermore, ten adult volunteers were administered 20 mL of 0.2% ropivacaine into the abdominal plane (corresponding to the M-TAPA plane) and the SEDIC, and a pinprick test was performed 1 h after the injection.

Cadaver macrodissection revealed the presence of the SEDIC adjacent to the M-TAPA plane. The SEDIC was completely spatially isolated from the M-TAPA plane by the presence of costal cartilage and/or tendinous structures. In the volunteer study, the administration of local anesthetics into the SEDIC effectively blocked the lateral cutaneous branches of T8–T12, in addition to the anterior branches.

Our study revealed the presence of the SEDIC adjacent to the M-TAPA plane. Administration of local anesthetics into the SEDIC, named re-modified TAPA, may have the potential to enhance the analgesic effect in the abdominal region.