Primidone/phenobarbital-induced periodic alternating nystagmus

Ann Ophthalmol. 1989 Jun;21(6):230-2.


A 37-year-old man with a history of seizures developed periodic alternating nystagmus (PAN) along with other signs of primidone/phenobarbital toxicity. The PAN gradually diminished in cycle length and intensity, finally resolving with gradual discontinuation of the drugs.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Electronystagmography
  • Eye Movements
  • Humans
  • Male
  • Nystagmus, Pathologic / chemically induced*
  • Periodicity*
  • Phenobarbital / adverse effects*
  • Primidone / adverse effects*
  • Visual Acuity


  • Primidone
  • Phenobarbital