[Normal latencies of cortical somatosensory evoked potentials--an additional criterion for the diagnosis of Rett syndrome].

In four girls aged from 2 1/2 to 17 years with Rett's syndrome confirmed on the basis of clinical criteria, somatosensorically evoked cortical potentials were led off contralaterally on both sides following stimulation of the median nerve (Med SEP). Like three other children with Rett's syndrome reported by Verma et al. (1987) the present author's patients had normal latency times. Determination of normal latency times for somatosensorically evoked potentials may thus be regarded as an important additional diagnostic criterion for the diagnosis of Rett's syndrome.