Patients will in the high-dependency area of the neurosurgical ward and will be reviewed frequently in the usual manner of patients receiving parenteral narcotics. Patients who develop pain will be encouraged to use the PCA. Any patient expressing dissatisfaction in their pain relief will be offered an injection of intramuscular morphine (50 mcg/kg) as a rescue medication up to every 2 hours. At the same time, the epidural infusion will be increased by 10 ml/h to a maximum of 40 ml/h. All patients will be visited by blinded study personnel at 1, 4, 24 and 48 hours for collection of data, and also twice daily by the hospital acute pain service. At the end of 48 hours, the epidural catheter will be removed and patients will be treated according to usual hospital pain management practices.