Page 152 - Prevention and Treatment of Incisional Hernia- New Techniques and Materials

Chapter 7
A similar nding was observed when comparing the left (colostomy) ARM with the right ARM postoperatively. The left ARM was thicker at 8cm cranial, 3cm cranial and at the level of the colostomy. However, caudal to the colostomy, the left ARM was actually thinner. This change may be caused by left ARM atrophy due to the denervation or damage to the intercostal /subcostal nerve after colostomy creation. Colostomies created during abdominoperineal resection or Hartmann procedures are generally situated in the lower left quadrant and positioned at the level of the 12th intercostal nerve. The iliohypogastric nerve which travels caudal to the 12th intercostal nerve does not innervate the rectus muscle and cannot compensate for any potential damage. Injury to the intercostal nerve would induce atrophy of the left ARM at the level of the colostomy and caudal. This e ect was partially obscured in this study due to overlap caused by the colostomy and possible herniation. The combination of an atrophy of the left ARM and the associated midline shift could be the cause of the increase of risk of IH observed in the PACIFIC-study(12). There has been discussion as to which position is preferential for colostomy placement. Currently, it is not known if colostomies should be placed through or lateral of the ARM. However, lateral of the ARM the intercostal nerves are less segmented and could be easier to detect and preserve (24). Additionally, a more cranial colostomy position could decrease atrophy to the ARM, because the 11th and 12th intercostal nerves are mainly responsible for ARM innervation (25). Furthermore, prophylactic mesh application at the level of the colostomy will decrease the chance of parastomal hernia formation and as a result will decrease possible long-term nerve damage due to compression(26). No literature, however, is currently available with regards to the e ects of these prophylactic measures on ARM atrophy.
Limitations
The main weaknesses of this study are the retrospective design and the limited number of patients. Due to the limited number of available preoperative CT-scans in this cohort, we were not able to perform statistical analyses with regards to IH or parastomal hernia and the midline shift. In addition, it is unknown what the impact a 5mm shift would have on the forces on the abdominal wall. This is something that might be investigated in the future with
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