Motor problems in children with early-treated congenital hypothyroidism: A matter of failing cerebellar motor control?

This study addresses the question of whether "clumsiness" in children with early treated Congenital Hypothyroidism (CH) might be attributable to cerebellar dysfunction. CH is known to affect rapid perinatal growth of the cerebellum. If this would affect the supposed motor timing function of the cerebellum this should be especially reflected by difficulty in producing fast aiming movements. An experiment was devised in which children made sequences of fast, goal directed movements in order to examine two aspects of fast voluntary movements that are known to be affected by cerebellar injury: dysmetria and dysdiadochokinesis. Three groups of children between the ages of 9 and ii participated: a group with severe CH (thyroid agenesis, n = 18), a group with mild CH (thyroid dysgenesis, n = 23) and a control group (n = 31). In comparison with controls, motor performance in children with severe CH was characterized by more overshoots, shorter movement times, higher velocity and a larger initial force Impulse. In line with previous findings from the same population, it is concluded that motor problems in early treated CH are primarily related to peripheral processes associated with motor execution rather than to central cerebellar processes associated with motor timing. (C) 1998 Elsevier Science B.V. All rights reserved.