“…In these prospective studies, the prevalence of DP ranged from 10% to 20% (Mok et al, 1991;Russell et al, 1991Russell et al, , 1993Russell et al, , 2008. However, a study conducted on a small number of children suggested that most prospective studies estimated the prevalence of phrenic nerve palsy on the basis of results from a single electrophysiologic evaluation performed within several days after operation and therefore the prevalence of significant phrenic nerve palsy, which may be transient, was overestimated (Imai et al, 2004). Imai et al (2004) recorded DAPs from 11 infants within 3 to 4 days after surgery and again 1 and 2 weeks after operation.…”