Rare case of Phenytoin induced movement disorders: A report

The case study found that

• Patient on the third day, the serum phenytoin level was 33 g/ml (10–20 g/ml). Adverse drug reaction (ADR) causality evaluations using the World Health Organization (WHO) causality assessment scale and Naranjo’s Algorithm revealed a “probable” time–temporal link of ADR.

• On the first day, the ADR was managed by withdrawing phenytoin from the regimen. He was given supportive treatment in the form of levetiracetam 500 mg and clonazepam 0.5 mg twice daily and thrice daily, respectively.

• For three days, the patient was kept hydrated with intravenous fluids. The patient was routinely monitored. By the third day after discontinuing phenytoin, involuntary movements had stopped.

The serum level of phenytoin may or may not be non-toxic. It is critical to consider phenytoin as a differential diagnosis in any patient who exhibits involuntary movements while on phenytoin medication. This is a case with a great prognosis following drug discontinuation/withdrawal ended the authors.

Reference: Shah, K.C., Patel, N.S., Vasani, P. et al. Phenytoin-induced dyskinesia: a case report. J Med Case Reports 17, 313 (2023). https://doi.org/10.1186/s13256-023-04033-6