Dorsal column stimulation: modulation of somatosensory and autonomic function

Electric stimulation of the posterior parts of the spinal cord (dorsal column stimulation), a direct clinical off-spring of the ‘gate-control theory’ presented 30 years ago, came into use as a means of relieving intractable pain only a few years later. The method was spread rapidly in the US and in Europe and is today an important adjunct in the therapy of selected pain syndromes resistant to other forms of treatment. Especially pain due to nerve injury, pain in peripheral vascular disease as well as angina pectoris are conditions which often respond to this treatment modality. Application of electric current to the dorsal columns evokes both ortho- and antidromic activity, the former being the base for the paraesthesiae experienced by the patient during stimulation. DCS seems to selectively suppress neurogenic types of pain, but the method also has a profound influence on pain in ischemia, probably via an entirely different mechanism. The somato-sensory and autonomic modulatory properties of DCS are the subject of this review, and in discussing this, we will also touch upon the question of the mechanisms underlying the beneficial effects. Furthermore, we will try to reflect the problems of generalizing observations from the laboratory, when DCS procedures are applied to subhuman subjects without concurrant disease, to the clinical setting and the suffering patient.