doi 10.17992/lbl.2026.10. 914

Olafur Arni Sveinsson^1,2

Agust Hilmarsson¹

Brynhildur Thors¹

 

¹Department of Neurology, University Hospital of Iceland, Reykjavik, Iceland, ²University of Iceland, Faculty of Medicine

 

Correspondence: Olafur Sveinsson olafursv@landspitali.is

Abstract

This case describes a serious but rare adverse effect of the antiepileptic drug valproic acid (valproate-induced encephalopathy) in a 65-year-old man. The patient was started on the treatment on questionable grounds due to a suspected single seizure. He remained on the medication for 10 years before progressively worsening parkinsonian symptoms were attributed to side effects of the drug. The medication was subsequently tapered off, after which it was as if a veil had been lifted from the patient. Functional capacity improved markedly and mental well-being increased. All suspicion of Parkinson’s disease disappeared. This case highlights the importance of carefully considering the diagnosis and treatment of patients with seizures, as well as maintaining a high level of awareness of adverse effects in patients receiving antiepileptic drugs who develop symptoms suggestive of dementia or neurodegenerative disease.