This study looked at 85 people enrolled in the UCDC longitudinal study. The goal was to understand how often seizures happen, what types occur, and whether ammonia and glutamine levels predict seizure risk during hyperammonemic crises. Researchers also examined the role of EEG in detecting seizures that are not obvious clinically. The group included both early-onset and late-onset UCD cases across several subtypes like OTCD, ASLD, ARG1D, CPS1D, and others. Data covered seizure history, EEG findings, and biochemical profiles during crises.
Key Takeaways
Seizures Are Common in UCD: About 34% of individuals had seizures at some point. Seizures occurred in 13% of hyperammonemic events, and most early-onset seizures happened during crises.
Epilepsy Risk Is Higher in Certain UCD Types: Overall, 12% developed epilepsy, mainly in distal UCD types like ASLD (22%) and ARG1D (50%). Late-onset seizures unrelated to crises were most likely to progress to epilepsy.
Ammonia and Glutamine Predict Seizure Risk: For every 100 µmol/L increase in ammonia, seizure odds rose 2.65 times; for glutamine, odds rose 1.14 times. Higher initial levels signal greater risk.
EEG Detects Hidden Seizures: EEG found subclinical seizures in 53% of crises with clinical seizures and 27% of crises with encephalopathy only. This shows why EEG monitoring is important during severe episodes.
Treatment During Crises: Seizures were managed with antiseizure medications (phenobarbital was most common) plus ammonia-lowering therapies like nitrogen scavengers and dialysis.
Why This Matters
Understanding seizure risk and epilepsy in UCD helps families and doctors plan care. Monitoring ammonia and using EEG during crises can prevent missed seizures and reduce brain injury.
Chanvanichtrakool M, Schreiber JM, Chen WL, Barber J, Zhang A, Ah Mew N, Schulze A, Wilkening G, Nagamani SCS, Gropman A; Urea Cycle Disease Consortium. Unraveling the Link: Seizure Characteristics and Ammonia Levels in Urea Cycle Disorder During Hyperammonemic Crises. Pediatr Neurol. 2024 Oct;159:48-55. doi: 10.1016/j.pediatrneurol.2024.06.013. Epub 2024 Jun 29. PMID: 39121557; PMCID: PMC11381174.
