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Updated: Aug 25, 2026
Infant Auditory Processing and Event-related Brain Oscillations
Published on: July 1, 2015
Evoked potentials show early and delayed abnormalities in children with congenital hypothyroidism
K Norcross-Nechay1, G E Richards, A Cavallo
1Department of Neurology, University of Texas Medical Branch, Galveston 77550.
Insights
Congenital hypothyroidism (CH) can affect nervous system development, causing delays in brainstem auditory evoked potentials (BAEP) and visual evoked potentials (VEP). Early treatment with thyroxine helps normalize these functions.
Area of Science:
- Neuroscience
- Endocrinology
- Pediatrics
Background:
- Congenital hypothyroidism (CH) is a condition that can impact infant development.
- Evoked potential studies are used to assess nervous system function.
Purpose of the Study:
- To evaluate the effects of congenital hypothyroidism on nervous system development in infants.
- To assess the impact of thyroxine treatment on these neurological functions.
Main Methods:
- Evoked potential studies (BAEP, VEP, SSEP) were performed on CH infants before and after treatment.
- Infants were diagnosed via T4 and TSH screening and confirmed with serum tests.
- Thyroid tissue presence and location were determined using a 99Tc scan.
Main Results:
- Brainstem auditory evoked potentials (BAEP) showed delays in caudal brainstem regions in untreated infants, normalizing after 6 months of thyroxine therapy.
- Visual evoked potentials (VEP) exhibited delayed and immature patterns in some infants at 4 weeks, but normalized by 8 weeks, even without treatment.
- Somatosensory evoked potentials (SSEP) were initially normal but showed prolonged central conduction times after 5 months of therapy.
Conclusions:
- Infants with mild CH demonstrate delayed visual system maturation, which can resolve spontaneously.
- Abnormalities in caudal brainstem development due to CH show slow resolution with thyroxine replacement therapy.
- Evoked potential studies are valuable tools for monitoring neurological development in infants with CH.
Abstract:
To evaluate the effect of congenital hypothyroidism (CH) on nervous system development, we performed evoked potential studies on 7 CH infants at 3-8 weeks of age before treatment and at four months or more after treatment began. All infants were screened using filter paper determination of T4 and TSH, confirmed by serum specimen determinations. These infants had serum TSH concentrations greater than 100 microU/ml (normal less than 7), and the serum T4 range was 4.1-8.5 micrograms/dl. All had thyroid tissue on 99Tc scan; five had ectopic thyroid tissue, and two had a thyroid gland in the normal location. Four older CH children were tested after 3-6 years of treatment. Brainstem auditory evoked potentials (BAEP) were abnormal in three of the 7 infants and showed bilateral conduction delays in caudal brainstem regions. The BAEP became normal after 6 months of thyroxine treatment. Visual evoked potentials (VEP) were abnormally delayed and had an immature pattern in the four patients tested at four weeks of age. At age 8 weeks, even in untreated patients, the VEP was normal and remained so. Somatosensory evoked potentials (SSEP) were normal at the time of diagnosis. However, seven patients tested after at least five months of therapy had prolonged central conduction times. We conclude that infants with relatively mild CH (serum T4 values greater than 4 micrograms/dl at 3-8 weeks of age) have evidence of delayed visual system maturation that becomes normal even without treatment and of abnormal caudal brainstem development that resolves slowly with replacement therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
