Effect of botulinum toxin A on random skin flap survival in rats

Introduction: Flap are commonly used as reconstructive option.one of the most important issue of the flap is their survival. Flap survival is dependent to their blood supply and blood drainage. Botulinum toxin type A Paralyzed autonomous nervous system of the blood vessels so decreased vasoconstriction and leads vasodilation. It seems this effect of the BTX-A can improve flap survival. Random Skin Flap is dependent to the weak intradermal vascular plexus so they have the least survival rate among all kinds of the flaps. So, any agent who improves survival of the RSF may improve survival of other kinds of the flap. We decided to study the effect of BTX-A on the survival of RSFs.Materials and Methods: Forty-five adult Sprague-Dawley rats were randomly divided into 3 equal groups. BTX-A, Saline and Control group with Cephalic-based RSFs were designed on each rat s back. BTX-A and Saline was injected sub dermally at the base of each flap corresponding to the group and nothing was done for rats of the control group. after 14 days, cephalic-based RSFs were harvested in all rat s back and the biopsy was done at the most distal part of each flap. These biopsies were evaluated for angiogenesis by H & E and also CD34 and CD33 staining. after 14 days the survived area of each flap was determined by photography and using AutoCAD program. Statistical analysis was performed using SPSS (ver. 12). A probability value of P < 0.05 was considered significant.Results: The average of survived flap area in the Botox-A, Saline and control groups were 71.38% (±15.70), 73.19 % (±21.03) and 59.01 % (±23.05), respectively (P-Value= 0.129). Histological examination revealed neovascularization was more in the Botox-A groups than control groups (P < 0.001). We have found significant difference in inflammation between the groups. (P < 0.001)Conclusion: In this study we found that using BTX-A increases the survival of the skin flap and reducing distal flap necrosis through promoting angiogenesis. Therefore, further experimental and clinical studies should be performed to prove this mechanism and further studies on the pre-surgical injection time are recommended.