Extremely Acute Phenytoin‐Induced Peripheral Neuropathy

PURPOSE: Peripheral neuropathy is a rare adverse effect associated with phenytoin (PHT), and it usually occurs after the prolonged use of PHT. Acute PHT-induced peripheral neuropathy is extremely rare. METHODS: An 18-year-old girl was admitted for the control of epilepsy. Just a few hours after the administration of PHT, she complained of distal lower-extremity paresthesia in a stocking distribution and motor weakness: the Achilles tendon reflex was absent. RESULTS: Electrophysiological studies revealed slightly reduced sensory-conduction velocity and mild prolongation of distal latency in the lower extremities. After the discontinuation of PHT, these symptoms disappeared gradually, and sensory-conduction velocity and distal latency became normal. CONCLUSIONS: Although it has been reported that peripheral neuropathy occurred after treatment with PHT for a week, there has been no report of a patient such as ours, who developed peripheral neuropathy just a few hours after the initial administration of PHT. The underlying mechanism remains unknown; however, we should pay attention to such extremely acute peripheral neuropathy when using PHT.