There was no difference between dexmedetomidine versus placebo groups in primary end points : change of somatosensory EPs at T@ , latency : @ @ ( -@ , @ ) vs @ @ ( -@ , @ ) , P = @ ( -@ , @ ) ; amplitude : @ @ ( -@ , @ ) vs -@ @ ( -@ , @ ) , P = @ ( -@ , @ ) ; motor EPs amplitude at T@ : @ @ ( -@ , @ ; n = @ ) vs @ @ ( -@ , @ ; n = @ ) , P = @ ( -@ , @ ) ; visual EPs at T@ ( right eye ) , amplitude : @ @ ( -@ , @ ; n = @ ) vs @ @ ( -@ , @ ; n = @ ) , P = @ ( -@ , @ ) ; latency N@ : @ @ ( -@ , @ ) vs @ @ ( -@ , @ ) , P = @ ( -@ , @ ) ; latency P@ : -@ @ ( -@ , @ ) vs -@ @ ( -@ , @ ) , P = @ ( -@ , @ ) or secondary end points .