Stimulation of the Central and Peripheral Nervous System for the Control of Pain

Abstract

After suffering some setbacks since its introduction in 1967, stimulation of the spinal and peripheral nervous systems has undergone rapid development in the last ten years. Based on principles enunciated in the Gate Control Hypothesis that was published in 1968, stimulation-produced analgesia [SPA] has been subjected to intensive laboratory and clinical investigation. Historically, most new clinical ideas in medicine have tended to follow a three-tiered course. Initial enthusiasm gives way to a reappraisal of the treatment or modality as side-effects or unanticipated problems arise. The last and third phase proceeds at a more measured pace as the treatment is refined by experience. This review is divided into three parts as it traces the progress of spinal cord stimulation [SCS] and peripheral nerve stimulation [PNS]. The review commences with a discussion of the theory of SCS and PNS, and is followed by early reports during which it became apparent that the modality is essentially only effective in the treatment of neuropathic pain. The last section describes the modern experience including efficacy in specific types of pain and concludes with recent accomplishments that dramatize the relief of pain which can be achieved in nonoperable peripheral vascular disease or myocardial ischemia. Over the years, a search for those transmitters that might be influenced by spinal cord stimulation focused on somatostatin, cholecystokinin (CCK), vasoactive intestinal polypeptide (VIP), neurotensin and other amines, although only substance "P" was implicated. More recently, in animal studies, evidence that GABA-ergic systems are affected may explain the frequent successful suppression of allodynia that follows spinal cord stimulation. During the past eight years, much attention has been directed to studies that use a chronic neuropathic pain model. While PNS held significant promise as a pain relieving modality, early electrode systems and their surgical implantation yielded variable results due to evolving technical and surgical skills. These results dramatically reduced the continued development of PNS, which then gave way to a preoccupation with SCS. Modern development of SCS with outcome studies, particularly in relation to failed back surgery syndrome [FBSS] and the outcome of peripheral nerve surgery for chronic regional pain syndromes, has earned both modalities a place in the ongoing management of patients with intractable neuropathic pain. The last section, dealing with pain of peripheral vascular and myocardial ischemia, is perhaps one of the more exciting developments in stimulation produced analgesia and as the papers discussed demonstrate, can provide a level of analgesia and efficacy that is unattainable by other treatment modalities. SCS and PNS has an important role to play in the management of conditions that are otherwise refractory to conservative or other conventional management.

Spinal cord stimulation in chronic pain syndromes

“…4,48 This opinion was con®rmed by a study of Barolat 35 who found that only patients with at least 50% pain relief at the time of implant were able to maintain the results over time. Di erent from most series on pain relief, however, Barolat did not use trial stimulation prior to the permanent implant.…”

“…26 Patients with only intermittent claudication or severely disabled patients who have also tissue loss like gangrene and ulcers respond less successfully to SCS treatment. 48 Patients with stage IV disease may respond to SCS, since ischemic ulcers 53 cm in diameter have been shown to heal well in response to stimulation. 49,50 In patients with established gangrene, no e ect from SCS will be obtained.…”

Median Nerve Stimulation in a Patient with Complex Regional Pain Syndrome Type II

“…SCS has been used to treat lower limb pain syndrome 5,8,15) . Severe CRPS start frequently at a focal point but then spreads to involve other limbs, and can become an almost systemic disease.…”

“…Patients with chronic peripheral nerve injury showed the best response 1,13,16) . Patients suitable for this form of neuromodulation include those with peripheral mononeuropathy (traumatic, idiopathic, or iatrogenic), a chronic entrapment syndrome, and CRPS 3,4,11,15) . The best predictor for success using a PNS implant to treat intractable pain is accurate patient selection.…”

Neuromodulation and Non-Pharmacological Treatment of Migraine

“…55,56 In conclusion, neuromodulation studies show some efficacy in the acute and preventive treatment of migraine. The results of vagal nerve stimulation are promising and sphenopalatine ganglion stimulation studies might be very interesting and may shed light into our understanding of pathomechanism of headache.…”