[MS2-2B-3] The utility of EEG monitoring in neonates with hyperammonemia due to inborn errors of metabolism
[Background] Small case series have demonstrated EEG changes and seizures during hyperammonemia associated with inborn errors of metabolism but there are no reports utilizing continuous EEG in these conditions.
[Objective] To characterize seizures and evaluate the utility of continuous EEG recording during hyperammonemia in inborn errors of metabolism.
[Method] We retrospectively reviewed medical records and EEG tracings of neonates who presented with hyperammonemia due to inborn errors of metabolism.
[Results] Seven neonates are included with: Argininosuccinate lyase deficiency, Urea cycle defects (3) and Methylmalonic acidemia (1). Most common presentations were lethargy and poor feeding at 12-72 hours of life. The highest blood ammonia level was 899 micromole/L (median); range 823-1647 micromole/L. All were treated with hemodialysis. Six neonates had seizures and five had only electrographic seizures. Seizures initially occurred within 24-36 hours of clinical presentation, sometimes with normal ammonia and glutamine levels. Neonates with seizures all lacked state changes on EEG. Interburst interval duration correlated with degree of hyperammonemia. Two cases with normal blood ammonia but increasing interburst interval duration were proven to have stroke by MRI.
[Conclusions] Seizures occur frequently and can be detected only with EEG in most neonates with hyperammonemia. Seizures can occur when ammonia and glutamine level is normal. Interburst interval duration can be associated with hyperammonemia or cerebral dysfunction from other brain pathology. Continuous EEG can be a useful tool for managing infants with hyperammonemia and may be essential for seizure management especially for infants in deep metabolic coma.
[Objective] To characterize seizures and evaluate the utility of continuous EEG recording during hyperammonemia in inborn errors of metabolism.
[Method] We retrospectively reviewed medical records and EEG tracings of neonates who presented with hyperammonemia due to inborn errors of metabolism.
[Results] Seven neonates are included with: Argininosuccinate lyase deficiency, Urea cycle defects (3) and Methylmalonic acidemia (1). Most common presentations were lethargy and poor feeding at 12-72 hours of life. The highest blood ammonia level was 899 micromole/L (median); range 823-1647 micromole/L. All were treated with hemodialysis. Six neonates had seizures and five had only electrographic seizures. Seizures initially occurred within 24-36 hours of clinical presentation, sometimes with normal ammonia and glutamine levels. Neonates with seizures all lacked state changes on EEG. Interburst interval duration correlated with degree of hyperammonemia. Two cases with normal blood ammonia but increasing interburst interval duration were proven to have stroke by MRI.
[Conclusions] Seizures occur frequently and can be detected only with EEG in most neonates with hyperammonemia. Seizures can occur when ammonia and glutamine level is normal. Interburst interval duration can be associated with hyperammonemia or cerebral dysfunction from other brain pathology. Continuous EEG can be a useful tool for managing infants with hyperammonemia and may be essential for seizure management especially for infants in deep metabolic coma.