1. A method of treating patients suffering from chronic or persistent pain, comprising the steps of: selectively applying a therapeutic stimulation signal from a stimulus generator, when activated, to at least some of plural electrodes implanted in stimulating relation to at least two nerves among the patient's trigeminal, vagus, glossopharyngeal and sympathetic nerves, and activating the stimulus generator to generate said therapeutic stimulation signal to alleviate the pain under treatment.