Long term results of peripheral conditioning stimulation as an analgesic measure in chronic pain.

In the present study 123 patients with chronic pain, consecutively referred for symptomatic pain treatment, were given peripheral conditioning stimulation as an analgesic measure and were followed for 2 years or till they terminated the treatment. The stimulation was either conventional transcutaneous nerve stimulation (TNS) [35] of mainly cutaneous afferents with high frequency (10-100 Hz) or acupuncture-like TNS [11] where muscle nerves are activated at a low repetition rate (1-4 Hz) with small trains of stimuli. The follow-up showed that 55, 41 and 31% of the patients continued the treatment after 3, 12 and 24 months, respectively. About 30% of the patients had to use acupuncture-like TNS to get useful analgesia, defined as a desire of the patient to continue stimulation treatment. Three-quarters of the successfully relieved patients reported more than 50% pain relief as measured from visual analogue scales and half of these reported an increased social activity and a decrease of analgesic drug intake by more than 50%. Psychogenic and visceral pains were less suitable for TNS treatment. It is concluded that peripheral conditioning stimulation is a valuable therapy in cases of chronic pain and that both conventional and acupuncture-like TNS should be tried before considering implantable devices or destructive surgery.