*4.7. Statistical Evaluation*

Data from recent studies [18,27] was used to calculate the required number of animals per experimental group to obtain a statistical power of 0.80 at an alpha level of 0.05, and a difference of at least 20% in behavioral responses after IoN-CCI surgery. The calculations were done using software (Lenth RV. Java Applets for Power and Sample Size) retrieved on 8 April 2013, from http://www.stat. uiowa.edu/~rlenth/Power, which estimated a sample size of 12 rats per experimental group.

Statistical analysis was performed with the GraphPad Prism program (GraphPad Software, San Diego, California, USA). In the MST, for each rat and at every designated time, a mean score for the five Von Frey hairs was determined. The IoN-CCI rats were compared to the sham-operated rats. For mRNA levels, results were analyzed using the ΔΔ*C*t method to compare expression of genes of interest with that of *GAPDH*, used as control gene. All data was tested for normality using the Kolmogorov–Smirnov normality test and considered normal. Differences between groups, or between

ipsilateral and contralateral sides, were analyzed by one-way analysis of variance (ANOVA) followed by Tukey's Multiple Comparison Test, or by means of two-way ANOVA followed by Bonferroni post-hoc test, respectively. Differences between two groups were analyzed by the Paired student's t test. A probability level of less than 5% was regarded as significant.
