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Neurophysiologic studies and cognitive function in congenital hypothyroid children
G Weber1, V Siragusa, G F Rondanini
1Department of Pediatrics, Scientific Institute, H San Raffaele, University of Milan, Italy.
Insights
Congenital hypothyroidism (CH) can cause subtle brain damage even with early screening. Neurophysiologic tests reveal abnormalities in screened and clinically diagnosed CH children, suggesting prenatal or perinatal central nervous system (CNS) issues.
Area of Science:
- Pediatric Endocrinology
- Neuroscience
- Developmental Pediatrics
Background:
- Congenital hypothyroidism (CH) is a condition where the thyroid gland doesn't produce enough thyroid hormone from birth.
- While neonatal screening detects CH early, some children still exhibit minor neurologic and intellectual deficits.
- The impact of early detection versus clinical diagnosis on neurodevelopmental outcomes in CH requires further investigation.
Purpose of the Study:
- To evaluate cognitive functions and neurophysiologic parameters in children with congenital hypothyroidism.
- To compare outcomes between CH children identified through neonatal screening and those diagnosed clinically before screening implementation.
- To identify potential central nervous system (CNS) damage in CH patients.
Main Methods:
- Cognitive functions were assessed using IQ evaluations.
- Neurophysiologic tests, including Auditory P300 and long latency somatosensory evoked potentials (LL-SEP), were performed.
- Two groups of CH patients (neonatal screening vs. clinical diagnosis) were compared to each other and to a healthy control group.
Main Results:
- Abnormal neurophysiologic tests were found in 82% of clinically diagnosed CH children.
- Surprisingly, 47% of CH children detected by neonatal screening, despite normal cognitive development, showed abnormal neurophysiologic tests.
- Significantly increased LL-SEP latencies were observed in both CH groups compared to controls, indicating CNS alterations.
Conclusions:
- Congenital hypothyroidism, even when detected early, may be associated with prenatal or perinatal CNS damage.
- Neurophysiologic testing can reveal subclinical abnormalities in CH patients, including those detected by screening.
- Early treatment may not fully prevent subtle neurodevelopmental impacts in some CH cases.
Abstract:
Minor neurologic and intellectual impairments have been described in some congenital hypothyroid (CH) children in spite of early detection by neonatal screening. The aim of our study was to assess cognitive functions as well as neurophysiologic parameters in hypothyroid children and to compare children detected by neonatal screening (group A) versus hypothyroid patients clinically diagnosed before the beginning of the screening program (group B). Group A consisted of 15 children (13 girls, mean age at the beginning of treatment 33 d). Group B consisted of 11 patients (7 girls, mean age at the start of treatment 10.1 mo). Twenty age-matched healthy children were studied as a control group for neurophysiologic tests. Neurophysiologic tests (Auditory P 300, long latency somatosensory evoked potentials (LL-SEP) were performed along with IQ evaluation. Abnormalities of neurophysiologic tests were detected in 82% of clinically diagnosed hypothyroid children. Surprisingly, 47% of the children detected by neonatal screening, having normal mental development index, showed at least one abnormal neurophysiologic test. LL-SEP latencies were found significantly increased in both groups of CH patients compared with controls. Our data are suggestive for a prenatal or perinatal CNS damage in some children with congenital hypothyroidism, despite early treatment.