DIFFERENCES BETWEEN CONGENITAL MIRROR MOVEMENTS AND ASSOCIATED MOVEMENTS IN NORMAL-CHILDREN - A NEUROPHYSIOLOGICAL CASE-STUDY

In this study we analysed how far physiological associated movements i n normal children (which may be present up to the age of 10 years) sha re the same physiological mechanism with clinically apparent mirror mo vements. Transcranial magnetic stimulation (TMS) and kinematic movemen t analysis were applied in a 4-year-old child with congenital mirror m ovements (CMM). The results were compared with a normative data base o f clinically normal children. In the child with CMM focal TMS of one m otor cortex induced bilaterally symmetrical responses in distal and pr oximal upper extremities muscles with identical ipsi- and contralatera l latencies. Also kinematic analysis showed a precise symmetrical onse t of intended and unintended contralateral movements, whereas normal c hildren with associated movements showed a variable movement onset del ay between extremities. The data suggest a different physiological mec hanism underlying these two varieties of elementary associated motor a ctivity in childhood. (C) 1998 Elsevier Science Ireland Ltd. All right s reserved.