Effect of botulinum-A toxin to cremaster muscle: an experimental study

Objective: A controversy exists on the definition, etiology and treatment of the retractile testes. In the present experimental study, we aimed to show the effect of botulinum-A toxin (Botox) on cremasteric muscle of a rat, and whether it may be an alternative to surgical treatment of retractile testis. Methods: Ten Wistar rats were used in the study. By stimulating cremasteric reflex, five compound muscle action potentials (CMAP) of the right and left cremasteric muscles of each rat were recorded using surface electrodes. Intramuscular injection of botulinum-A toxin was done to the right side. Saline was injected to the left cremasteric muscles, and the left side also served as control. CMAP of the cremasteric muscles were recorded 45 days after the injection. Statistical analysis was done using Wilcoxon Signed rank test. Results: Mean CMAP of the right side was 3.25±1.39 µV before the injection and 0.44±0.25 µV after botulinum-A toxin injection. The difference was statistically significant (p<0.05). Mean CMAP on the left side was 3.48±0.32 µV and 3.14±1.12 µV at baseline and the end of the study, respectively. The difference was not statistically significant (p>0.05). Conclusion: The botulinum-A toxin paralyzes the cremasteric muscles of the rats. As cremasteric hypertonicity is accepted as one of the reasons for retractile testes, botulinum-A toxin injection to cremasteric muscles may be helpful in diagnosis and may be an alternative to surgical treatment of this pathology in repeated dosages. Long-term evaluation of this paralysis is necessary.