ESPE Abstracts (2014) 82 FCLB4

Does Severity of Hypothyroidism at Birth Contribute to Abnormal Cortical Development among Children with Congenital Hypothyroidism?

Joanne Roveta,b, Hayyah Clairmanb & Jovanka Skocicb

aUniversity of Toronto, Toronto, Ontario, Canada; bHospital for Sick Children, Toronto, Ontario, Canada

Background: Despite early detection and treatment, children with Congenital Hypothyroidism show subtle persisting deficits in various cognitive abilities. Degree and type of deficit reflect CH severity at time of diagnosis. We reported (Rovet et al., ATA, 2012) children with CH had abnormal cortical morphology, consistent with animal evidence showing early thyroid hormone (TH) insufficiency affects cortical development. It is not known, however, whether these cortical abnormalities reflect hypothyroidism severity at diagnosis.

Objective: To correlate indices of cortical morphometry and CH severity at birth.

Method: 41 CH and 42 controls matched for age and sex (age=9–16 years) were assessed for intelligence and memory and received a 1 h MR scan. Scans were analyzed using FreeSurfer to determine cortical thickness (CT) levels; CT values were correlated with TSH and T4 levels at diagnosis, compared by CH etiology, and correlated with test results.

Results: Lower T4 and higher TSH at diagnoses were associated with i) cortical thinning in the right superior and middle frontal gyrus, left superior temporal gyrus, right inferior parietal gyrus and parieto-occipital sulcus, and left lateral fissure and ii) cortical thickening in left superior frontal gyrus and middle frontal sulcus, right postcentral gyrus, right inferior temporal sulcus, left calcarine sulcus. Children with athyrotic etiology showed thinning of right occipital gyrus and thickening of left middle frontal and inferior parietal gyri relative to ectopic etiology. Lower IQ was associated with thickening or left middle frontal gyrus and superior frontal gyrus and poorer delayed visual memory performance with thickening of left superior frontal and temporal gyri and right superior parietal and occipital gyri.

Conclusion: Early TH insufficiency in CH prior to treatment onset contributes to abnormal cortical morphology in critical brain regions for intellectual and other cognitive functions.

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