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Pain


Peripheral Nerve Stimulation for Neuropathic Pain Konstantin V Slavin, MD, FAANS


Professor, Stereotactic and Functional Neurosurgery, Department of Neurosurgery, University of Illinois at Chicago


Abstract


Over the last two decades, electrical neuromodulation has become a dominant approach in surgical treatment of medically refractory neuropathic pain, essentially eclipsing multiple available neuroablative procedures. Among different types of neuromodulation, peripheral nerve stimulation (PNS) holds the unique position of being the least invasive—and at the same time the least established in terms of scientific evidence and regulatory approvals. However, it is now gaining tremendous momentum in terms of accumulation of clinical experience and development of new indications. As a matter of fact, recent European approval of PNS for treatment of chronic low back pain and intractable migraine headaches is expected to add legitimacy and marketing support to the entire field of PNS. This article provides an overview of PNS history, reviews current thoughts regarding its mechanism of action, summarizes common indications, clinical outcomes, technical procedural details, and complications, and suggests future directions for PNS development. It appears that PNS today is the most rapidly growing field of neuromodulation—and that does not come as a surprise, considering its potential for treatment of very prevalent and hard-to-treat conditions, such as back pain and headaches. From the point of view of a practicing neurologist, PNS presents an attractive pain management option that combines a high level of efficacy and reproducibility of results with low invasiveness and minimal morbidity. As the worldwide experience with PNS continues to grow, one may expect to see it becoming a widely accepted treatment approach in a variety of clinical conditions.


Keywords Neuromodulation, low back pain, migraine, complex regional pain syndrome, neuropathy, pain management, implantable technology


Disclosure: Konstantin V Slavin, MD, FAANS, is a consultant, speaker, educator, recipient of educational grants, and/or member of advisory board for the following medical device companies: Medtronic, St. Jude Medical, Boston Scientific, Bioness, Greatbatch, BSI, MSEI, and Vycor Medical. Received: November 21, 2011 Accepted: December 18, 2011 Citation: US Neurology, 2011;7(2):144–8 Correspondence: Konstantin V Slavin, MD, FAANS, Department of Neurosurgery, M/C 799, 912 South Wood Street, Chicago, IL 60612. E: kslavin@uic.edu


Peripheral nerve stimulation (PNS) is a unique neuromodulation modality that is rapidly gaining popularity for a variety of clinical conditions. Despite its straightforward nature, the modality has been for a long time treated as a ‘stepchild’ of the neuromodulation field, yielding the spotlight to the more ubiquitous spinal cord stimulation (SCS) and the more elegant deep brain stimulation (DBS) approaches. Interestingly enough, the main theoretical explanation of the neuromodulatory treatment of pain, the ‘gate control theory’ of Melzack and Wall1


was first illustrated by an


example of PNS when courageous investigators were able to suppress pain perception with electrical stimulation of their own infraorbital nerves using percutaneously inserted electrodes.2


Since its introduction in the late 1960s, PNS went through several stages of development.3


Although there were many enthusiastic centers and clinical series describing the use of PNS in a variety of neuropathic pain conditions, the modality did not become popular for more than 30 years. The complexity of PNS procedures, with the need to expose the targeted nerve and secure the stimulating electrode, and the unpredictability of PNS outcomes, along with the lack of dedicated and approved PNS equipment, resulted in its lack of widespread acceptance. However, even in the 1970s and 1980s, several large series showed the usefulness of PNS in the treatment of neuropathic pain syndromes, including


144


chronic pain associated with peripheral nerve injury and complex regional pain syndromes.4–9


The situation changed in the late 1990s when a percutaneous PNS approach was described by Weiner and Reed.10


The simplicity and elegance


of a surgical procedure that did not require major exposure to achieve direct contact between the nerve and electrode lead, but instead allowed one to put the electrode in the vicinity of the nerve to be stimulated, revolutionized the field. Among other implications, the introduction of a percutaneous approach gave an opportunity to use PNS to pain specialists with a background in anesthesia or physiatry, whereas in the past this modality was only available to neurosurgeons and orthopedic and plastic surgeons who felt comfortable exposing and dissecting peripheral nerves.


Definition of Peripheral Nerve Stimulation PNS in its pure sense has traditionally referred to a modality where electrical impulses are delivered directly to the peripheral nerve. In the past, this involved surgical exploration of the nerve and placing an electrode array directly on it—using either a flat paddle that touched the nerve or was separated from it by a thin fascial layer, or a spiral electrode that could be wrapped around the nerve trunk. Independently of the electrode/nerve interface, the principle of PNS remains the same,


© TOUCH BRIEFINGS 2011


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