The number of attacks was determined according to the patients' diaries. Boxplots for outcome measures during the placebo, fampridine, and acetazolamide treatment phases (box-whisker plot with 25% and 75% percentiles [borders of the boxes], the median [line], whiskers [extend to the most extreme data point, which is no more than 1.5 times the interquartile range from the box], and outliers).