Amplitude-integrated electroencephalography in newborns with inborn errors of metabolism

Background: The utility of amplitude-integrated electroencephalography (aEEG) monitoring has been established for patients with neonatal hypoxic-ischemic encephalopathy. Objective: To evaluate the role of aEEG in the diagnostic process and treatment of patients with encephalopathy due to inborn errors of metabolism. Methods: Cases collected through an international registry were divided into 5 groups of metabolic disorders. Common aEEG features were sought for each group. Results: In total, 21/30 (70%) cases had abnormal aEEG background patterns, 18/30 (60%) showed seizure activity. Patients with disorders of energy metabolism, hyperammonemia, and organic/amino acidopathies often showed marked aEEG depression with seizure activity. In contrast, aEEGs of patients with peroxisomal disorders did not show major background abnormalities but seizures were present in 5/6 subjects. We report two features of interest: firstly, two tracings displayed an unusual upward shift of the lower aEEG amplitude margin. Secondly, aEEGs of infants with non-ketotic hyperglycinemia showed a pattern we refer to as 'high-frequency burst-suppression pattern'. Conclusions: aEEG in patients with inborn errors of metabolism frequently reveals abnormalities and assists clinicians in the clinical assessment, management and monitoring of these patients.