1203 Impaired neuromotor outcome in adolescents with treated congenital hypothyroidism

While the impact of congenital hypothyroidism on intellectual development is usually the focus of attention in studies related to early diagnosis and treatment of the condition, there have been a few studies into the long-term effects on motor functioning. However these are also limited in terms of the duration of follow-up. To gain greater insight into the matter, researchers at the University Children’s Hospital in Zurich studied a cohort of 89 children diagnosed by neonatal screening between 1978 and 1991 (almost 9 cases per annum). Treatment with high dose laevothyroxine was initiated at a median age of 9 days, and 63 were followed up until a median age of 13.8 years (range 7-14.2 yrs). The thyroid was dysgenetic in 33 and absent in 26. A previous follow-up study of the same cohort until 14 years of age showed a significantly lower mean IQ than the normal population despite the early diagnosis and high-dose treatment intervention, while this study showed significant impairments of fine motor function, with athyreotic subjects performing at a lower level than those with dysgenesis. The ratio of females to males was almost 4:1, but males were more affected motor-wise than the females. An important implication of the study is again that neurodevelopmental damage begins prenatally and is not reversed or completely prevented by early postnatal diagnosis and treatment. The clinical significance of these motor impairments will obviously depend on their severity, but also on the spill-over to other developmental areas. For example it has been shown that motor problems in childhood may be associated with visuomotor and/or visuoperceptual problems and there could be consequences in terms of writing and performing other tasks that require fine motor coordination and control. It appears that hormone replacement therapy on its own does not prevent the adverse neuromotor effects; a question remains as to whether physio- or occupational therapy would be beneficial.

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