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Valproic acid-induced hyperammonaemic coma and unrecognised portosystemic shunt
Hipólito Nzwalo1, Leonor Carrapatoso, Fátima Ferreira
1Neurology Department, Faro Hospital, Faro, Portugal. nzwalo@gmail.com
Summary
Valproic acid can cause hyperammonaemic coma, especially in patients with undiagnosed liver issues like portosystemic shunts. Prompt dialysis can effectively treat this serious complication.
Area of Science:
- Neurology
- Toxicology
- Hepatology
Background:
- Valproic acid is a common antiepileptic drug.
- Hyperammonaemic encephalopathy is a rare but serious side effect.
- Portosystemic shunts can impair ammonia detoxification.
Observation:
- A patient with an unrecognized portosystemic shunt developed hyperammonaemic coma while on valproic acid for epilepsy.
- The patient had no signs of chronic liver disease, delaying diagnosis.
- The coma was refractory to other treatments.
Findings:
- Valproic acid precipitated severe hyperammonaemic coma in a patient with an undiagnosed portosystemic shunt.
- The underlying liver condition (portosystemic shunt) was secondary to alcoholism.
- Dialysis was effective in resolving the hyperammonaemic coma.
Implications:
- Highlights the importance of considering hyperammonaemic encephalopathy in patients on valproic acid, even without overt liver disease.
- Undiagnosed portosystemic shunts are a critical risk factor for valproic acid-induced hyperammonaemia.
- Dialysis is a viable treatment for refractory cases of valproic acid-induced hyperammonaemic coma.
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