HYPERALGESIA AND MYOCLONUS IN TERMINAL CANCER-PATIENTS TREATED WITH CONTINUOUS INTRAVENOUS MORPHINE

Eight cancer patients in the terminal stages of the disease treated wi th high doses of intravenous morphine developed hyperalgesia. All case s were retrospectively sampled from three different hospitals in Copen hagen. Five patients developed universal hyperalgesia and hyperesthesi a which in 2 cases were accompanied by myoclonus. In 3 patients a pre- existing neuralgia increased to excruciating intensity and in 2 of the se cases myoclonus occurred simultaneously. Although only few clinical descriptions of the relationship between hyperalgesia/myoclonus and h igh doses of morphine are available, experimental support from animal studies indicates that morphine, or its metabolites, plays a causative role for the observed behavioural syndrome. The possible mechanisms a re discussed and treatment proposals given suggesting the use of more efficacious opioids with less excitatory potency in these situations.