Downbeat nystagmus due to anticonvulsant toxicity.
Isolated downbeat nystagmus was observed in 2 patients on multiple anticonvulsant regimens. The nystagmus disappeared when phenytoin dosage was reduced. Electrooculographic analysis revealed impaired downward tracking, supporting the concept of "pursuit" nystagmus.
D000328:Adult; D000927:Anticonvulsants / Q000009:adverse effects*; D002220:Carbamazepine / Q000009:adverse effects; D005133:Eye Movements; D005260:Female; D006801:Humans; D009759:Nystagmus, Pathologic / Q000139:chemically induced* / Q000503:physiopathology; D010672:Phenytoin / Q000009:adverse effects; D011324:Primidone / Q000009:adverse effects
D000927:Anticonvulsants; D011324:Primidone; D002220:Carbamazepine; D010672:Phenytoin