he primary outcome of this study was time of 2 dermatomes regression of sensory level in relation to the maximal level. he sample size was calculated using G*power,version 3.1.9.2. Based on a previous study the effectsize (d) was determined to be 0.4 after converting the median and interquartile range to mean and standard deviation [13], the effect size d = 0.4. With a power of 80% (using a two-sided t-test and an α level of 0.5) theestimated sample size needed for the study was approximately 200 patients (100 in each group).