Encephalopathy in an infant with infantile spasms: possible role of valproate toxicity

Area of Science:

• Pediatric Neurology
• Clinical Pharmacology

Background:

• Infantile spasms and global developmental delay are serious pediatric neurological conditions.
• Sodium valproate is a common antiepileptic drug used in pediatric practice.

Observation:

• An infant with infantile spasms developed encephalopathy, including vomiting and altered sensorium, after initiating sodium valproate therapy.
• Initial investigations for hyperammonaemia and hepatic encephalopathy were normal.
• Seizures increased despite treatment, and symptoms resolved dramatically upon valproate withdrawal.

Findings:

• The adverse drug reaction (ADR) of valproate-induced encephalopathy was confirmed using the Naranjo ADR probability score.
• This case is the youngest reported instance of valproate-induced encephalopathy with normal liver function and ammonia levels.
• Marginal elevation in serum valproic acid levels was noted.

Implications:

• Valproate toxicity can manifest as encephalopathy even with normal liver function tests and serum ammonia.
• Clinicians should consider valproate-induced encephalopathy in infants presenting with neurological deterioration on the medication.
• This highlights the importance of careful drug monitoring and considering rare ADRs in pediatric epilepsy management.