Introduction. The goal of our study was to compare results in patients with large midline incisional hernia (LMIH) using only anterior compònent separation (CST) versus preoperative botulinum toxin (BT) and following Rives repair (RSR).

Material and methods. From to December 2016 to December 2018, a prospective comparative study was performed in 80 consecutive patients with LMIH and hernia transverse diameter between 12-18 cms at our tertiary center. Two groups were prospectively analyzed: patients underwent open CST (component separation group or CSG) and patients with preoperative BT administration and following open RSR (botulinum toxin group or BTG).

Multiple techniques have been described to decrease tension in the closure of the hernia defect in the large midline incisional hernias (LMIH) (1). Anterior component separation (CST) has demonstrated to accomplish primary fascial closure, while maintaining normal anatomy and physiology of the abdominal wall (2,3). However, described limitations of this technique are complications involving the skin and subcutaneous tissue, most likely caused by surgical interruption of perforating vessels during exposure of the external oblique muscle. So, CST has been related to surgical site occurrences (SSO), especially skin necrosis, up to 17% of cases, as well as recurrence rates between 7 and 18% (4).

On the other hand, botulinum toxin type A (BT) has been reported as a therapeutic option to decrease tension of a fascial closure in LMIH (5). It is a neurotoxin that causes a reversible denervation and paralisis of the lateral abdominal muscle, and has been considered as a "chemichal component separation" by some working groups (6). Our long experience about use of preoperative techniques like BT and progressive pneumperitoneum (PPP) allowed us to raise the possibility of planning the isolated use of BT in case of long transverse hernia diameters in patients with LMIH (7).

Taking advantage of the beneficial effect of the neurotoxin, we considered interesting to try to downstage the CST to other hernia repair with less morbidity, like Rives-Stoppa retromuscular repair (RSR). This technique has been traditionally considered the gold standard technique in midline hernias, especially in hernia defects with transverse diameters around or less than 10 cms, and appears to be more advantageous compared to other surgical techniques concerning complications and recurrence rates (8). RSR achieves several objectives: a tension-free closure due to extensive overlap between the prosthesis and the fascial edges, and the placement of the mesh next to the vascular-rich rectus muscles facilitates tissue incorporation and minimizing complications related to SSO (9).

The objective of our study was to compare results in two groups of patients with LMIH, using only CST versus preoperative BT plus following RSR, focusing on the SSO, possibility of primary fascial closure, length of hospital stay and hernia recurrence rate.

Inclusion Criteria:

• patients with LMIH with hernia transverse defect between 12 and 18 cms in preoperative CT scan
• grade W3 in EHS classification

Exclusion Criteria:

• patients with loss of domain hernia (Tanaka index over 20% in CT scan)
• laparoscopic approaches
• hernias not involving the midline, such as isolated flank and parastomal defects.