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Abstract
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Background and Aims Modified thoracoabdominal nerve block through perichondrial approach (M-TAPA) is a novel truncal block first reported by Tulgar et al in 2019. It has been reported to anesthetize a broad thoracoabdominal area; however, the neuroanatomical mechanisms remain unclear. Therefore, we conducted a volunteer study employing magnetic resonance imaging (MRI) to investigate the diffusion pattern of the local anesthetic responsible for extensive sensory area.
Methods This study was approved by the Institutional Review Board of Hokkaido University Hospital. Three healthy male volunteers were involved. Bilateral M-TAPA was performed, administering 25 mL of Gadavist® containing 0.15% levobupivacaine on each side. The local anesthetic was precisely injected between the origin of the transversus abdominis muscle and the costal cartilage following Tulgar’s description. One hour following the administration, the sensory area and local anesthetic diffusion were assessed using pinprick tests and MRI, respectively.
Results The 6 blocks in the 3 volunteers were evaluated. The sensory loss areas at 1 hour after M-TAPA were; T9, T9–10, T9–10, T8–9, T9, and T9–10. No effect was observed in the lateral area. The MRI revealed that local aneshtetic was distributed in the transversus abdominis plane near the injection point, and the compartment on the surface of the parietal peritoneum.
The sensory areas 1 hour following M-TAPA
The MRI imaging of the local anesthetic spread
Conclusions In this study, the sensory loss of M-TAPA was limited to the T8–10 in the anterior abdominal wall. Also, MRI tests did not detect a local anesthetic diffusion pattern that could lead to broad anesthetized area. These results indicate the necessity of caution in presuming the extensive anesthetized area of M-TAPA.