The Therapeutic Hypothermia in Treatment of Hyperammonemic Encephalopathy due to Urea Cycle Disorders and Organic Acidemias

Background Hyperammonemic encephalopathy in newborns with urea cycle disorders and certain organic acidurias can cause severe brain injury, coma and death. Standard therapy includes protein restriction, nitrogen-scavenging drugs, prevention of catabolism and hemodialysis. Neuroprotective hypothermia as part of the treatment has been reported only 3 times. It has been suggested that mild systemic hypothermia can contribute to better neurological outcomes in hyperammonemic encephalopathy. However, the limited experience precludes accurate conclusions on safety and efficacy. Methods Whole body therapeutic hypothermia was included in the standard treatment of hyperammonemic encephalopathy in 4 neonates with urea cycle disorder or organic aciduria. Results Two patients survived the initial crisis. One patient has a developmental quotient of 0.8, while the other shows severe developmental delay. The cooling protocol had to be discontinued in 3 patients due to the otherwise untreatable complications (hypotension and hemorrhage). Conclusion The efficacy and safety of therapeutic hypothermia in the treatment of neonatal hyperammonemic encephalopathy depend on various factors, requiring further evaluation.