Effect of paralysis of the abdominal wall muscles by botulinum A toxin to intraabdominal pressure: an experimental study.

PURPOSE: To show the effect of botulinum A toxin-induced paralysis of abdominal muscles on intraabdominal pressure.
MATERIAL AND METHODS: Fifteen Sprague-Dawley rats were divided into 2 groups. An abdominal skin incision was done, and 2 catheters were placed for the pressure monitoring and saline infusion. Saline solution was given to the abdomen until reaching to a pressure level of 9 cm H2O and 6 mm Hg in pressure device, and the amounts of injected saline were recorded. Then intraabdominal saline was drained. Two milliliters (5 U/mL) botulinum A toxin was applied to the abdominal muscles in group 2. Saline was injected at the same points in same amounts in group 1. After 3 days, catheters were placed, and the saline volumes needed to obtain the same pressure levels were recorded for each rat. Spontaneous motor unit potential (MUP), single MUP analysis and interference patterns of the muscles, respiratory rates, and vascular pressure measurements were recorded before and after botulinum toxin (Botox) injections.
RESULTS: Mean intraabdominal saline volumes in the first and third days were 63.8 and 64.4 mL in group 1 and 67.6 and 80.6 mL in group 2, respectively. Mean MUP amplitude and duration of the rectus muscles in group 2 (17.1 microV and 1.47 milliseconds) were significantly lower than those of group 1 (187 microV and 4.9 milliseconds) in the third day. There were no pathological changes in respiratory rates and pressure measurements before and after Botox injections.
CONCLUSION: This pilot experimental study showed that local injection of botulinum A toxin causes paralysis in abdominal wall muscles, increases the intraabdominal volume, and decreases the pressure, and this application may be used as an adjunct in abdominal wall closure in selective cases.