Deficient inhibitory processes within the sensorimotor circuit, reflected by a shortened cortical silent period (CSP), have previously been described in both children and adults with
tic disorders (TD) using
transcranial magnetic stimulation (TMS). In contrast to adults,
tic distribution (presence or absence of distal
tics) did not affect CSP duration in children. The aim of this developmental TMS study was to clarify this striking difference. 127 children with TD were stratified into three age-groups (8-11.5, 11.5-15, 15-19 years) with and without distal
tics. CSP was recorded from the abductor digiti minimi. Statistics revealed a significant
tic distributionxage interaction effect. Only in the 15-19 years subgroup, CSP was shorter in patients with distal
tics in comparison to patients without distal
tics (94.1+/-54.1 ms versus 135.2+/-36.8 ms at a stimulus intensity of active motor threshold plus 30%). Inhibitory processes in the sensorimotor circuit could reflect developmental aspects of
tic phenomenology, particularly
tic distribution during adolescence.