Interferon-Induced Vertigo-A Clinical Study of 2 Patients

Neurotological findings of two patients with chronic hepatitis C who developed ver-tigo after interferon therapy are described. The patients were a 62-year-old male who developed dizziness after intramuscular injections of interferon-α and a 55-year-old female who developed positional vertigo after intramuscular injections of interferon-α-2a. Down-beating positional nystagmus was observed in the supine and the supine head-down positions in both patients, but no gaze nystagmus or spontaneous nystagmus was noted. Signs and symptoms were relieved after reduction of the dose of interferon. Elec-tro-nystagmographic (ENG) studies were performed before and after an injection of in-terferon in the female patient. She exhibited hypermetric saccades and increased size of the down-beating positional nystagmus in ENG recorded 6 hours after the interferon in-jection. Several pathophysiological hypotheses about interferon-induced vertigo, in-cluding direct effects of interferon on the central nervous system, are discussed, but they are still to be proved by basic and clinical studies.