2.6. Sample Size
cerebral infarction, vasospasm
CEREBRAL INFARCTION, VASOSPASM
In the absence of available data from the literature, the aim of this pilot study was to estimate the clinical and radiologic efficacy of TNS in reducing the risk of developing cerebral infarction related to vasospasm in a limited number of patients. However, even if limited, the number of patients had to be sufficient to guarantee minimum acceptable statistical power. A minimum size of 30 patients per group (60 patients in total) allowed the detection of a 30% estimated difference between the two groups (65% vs. 35%) with a power of 80% (one-tailed Fisher test at 5% risk).