Which abnormal neonatal EEG findings are characteristic of inborn errors or metabolism?

Updated: Oct 03, 2019
  • Author: Rosalia C Silvestri-Hobson, MD; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Periodic EEG patterns in newborns with uneventful deliveries strongly suggest the possibility of an inborn error of metabolism. The most frequent neurological symptoms are early movement disorders, convulsions, and cognitive dysfunction. In 1977, Mises accurately described periodic EEG patterns in methylmalonic aminoacidopathy. [5]

High interindividual variability characterizes a pattern of periodic frontal or occipital sharp waves that are interspersed with rapid rhythms. In maple syrup urine disease, EEG complexes are low-voltage and less periodic; background activity is less depressed. Comb-like rhythms during the second and third postnatal weeks are pathognomonic of this disorder.

The highly peculiar EEG pattern of non-ketotic hyperglycemia distinguishes it from other forms. During the first 10 postnatal days, these infants, who present with hypotonia, respiratory distress, and myoclonic seizures, have EEGs characterized by periodic, highly stereotyped 1–3 Hz complexes with 4- to 18-second interburst intervals. Frontal, high-voltage slow waves are associated with characteristic rolandic and occipital early alpha rhythms.

Pyridoxine dependence (not to be confused with pyridoxine deficiency) is inherited as an autosomal recessive trait and is accompanied by severely abnormal EEGs and refractory seizures that only respond to pyridoxal supplementation.


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