F-chronodispersion in patients on thalidomide

Objectives: To describe abnormalities of F-chronodispersion in patients treated with thalidomide. Methods: We retrospectively studies F-wave latency, persistence and F-chronodispersion in 12 patients on thalidomide treatment and compared them with a control group of another 12 patients with similar dermatological conditions who did not receive thalidomide. Furthermore, we prospectively performed longitudinal neurophysiological studies in 4 patients before and during thalidomide treatment. Results: Seven of 12 patients in the retrospective study had abnormal F-chronodispersion while this was normal in all patients of the control group (P=0.014). All other neurophysiological parameters were similar in the two groups. Two of the thalidomide patients with abnormal F-chronodispersion later developed sensory neuropathy. In all 4 patients in the prospective study though F-chronodispersion was normal before thalidomide it became markedly abnormal after exposure to this drug. Conclusions: Thalidomide may affect smaller diameter motor nerve fibres even before changes in sural sensory nerve action potentials. F-waves and F-chronodispersion should be routinely monitored in patients on thalidomide treatment.