Neurotoxic effects of long-term treatment with low-dose alpha 2b interferon

Seventeen patients with relapsed or resistant non-Hodgkin's lymphoma were treated with alpha 2b interferon (IFN) from March 1986 to February 1988. All patients received IFN alone in a dose of 2-10 million/m² IU subcutaneously three times a week. In patients resistant to this treatment an IFN-chemotherapy combination was administered. Fatigue was quite frequent (35%) but never severe. Taste alterations occurred in eight of 17 patients. Vertigo and cramps were observed in five and two patients, respectively. All patients showed electroencephalogram (EEG) changes. Slowing of the dominant alpha rhythm with the appearance of diffuse theta waves was almost always observed, but in only eight patients were these alterations localized mainly in specific areas. Behavioral changes were the most pronounced side effect, but were usually reversed at the end of the therapy. Our results confirm the literature data on the lack of correlation between EEG changes and clinical symptoms. It is not clear what mechanism is involved in the occureence of neurotoxicity by IFN; involvement of neurotransmitters, rather than direct neuronal damage, might be the case.