Preoperative Botulinum Toxin A Injection in the Management of Giant Scrotal Hernia with Loss of Domain: A Volumetric and Clinical Case Study.

<b>Introduction:</b> Botulinum toxin type A (BTA) has emerged as a preoperative adjunct in complex ventral hernia repair, particularly in cases with loss of domain (LOD), yet volumetric evidence of its effect on abdominal wall geometry remains scarce.<b>Aim:</b> To evaluate the impact of BTA on abdominal cavity expansion and lateral muscle elongation in a patient with extreme LOD using volumetric computed tomography (CT) and geometric modeling.<b>Materials and methods:</b> A 61-year-old male with a giant left scrotal hernia and LOD (Tanaka index >25%) underwent BTA injections into the lateral abdominal wall, followed by CT imaging pre- and post-treatment. 3D reconstructions were generated to assess intra-abdominal volume and muscle lengths at three anatomical levels.<b>Results:</b> Abdominal cavity volume increased by 28.1% (13.74 L to 17.61 L), allowing safe visceral reintegration without abdominal compartment syndrome. The transversus abdominis exhibited the most pronounced elongation and volume gain (up to 329% elongation, 62% volume increase), while the external and internal obliques showed elongation with concurrent volume loss. The least elongation occurred at the costal level, highlighting anatomical rigidity in this region.<b>Discussion:</b> The results confirm that BTA-induced elongation varies by muscle and anatomical location. Minimal elongation at the subcostal level aligns with the known difficulty in closing M1-type hernias due to restricted superior abdominal wall mobility.<b>Conclusions:</b> BTA facilitated fascial closure by altering abdominal wall mechanics and increasing the intra-abdominal domain.<b>Significance:</b> This study is the first to combine volumetric and geometric modeling to objectively quantify BTA's mechanical impact, offering new insights into patient selection and planning for hernia repair with LOD.