Peripheral Subcutaneous Stimulation for Intractable Pain

Published on 24/02/2015 by admin

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Chapter 20 Peripheral Subcutaneous Stimulation for Intractable Pain

Chapter Overview

Chapter Synopsis: Peripheral subcutaneous stimulation (PSS) provides a minimally invasive form of neurostimulation for intractable pain. This technique, also called peripheral nerve field stimulation, targets the small, arborized fibers in subcutaneous tissue. Originally developed to treat areas difficult to reach with stimulation of the nerve trunk or spinal cord, PSS shows promise in other areas, rendering more central implantation unnecessary. Technical details of device selection should always be considered in advance of implantation. PSS may be optimized with cylindrical rather than paddle leads used in some other applications. Further consideration should be given to the size and site of the painful area to be treated. Large areas of the body can be treated with multiple, widely spaced leads. This chapter provides several technical considerations for optimal implantation. The primary indications for PSS are back pain and headaches that may be neuropathic or nociceptive in origin. The most promising patient candidates can pinpoint areas of their worst pain and the area from which pain originates. Because stimulation is achieved directly at the pain site, precise placement is critical to success. Transcutaneous external nerve stimulation can be considered a less invasive option to PSS and, if effective, should be used in place of PSS. Although PSS is minimally invasive and avoids many risks associated with spinal stimulation, some complications are common to it, including infection and lead migration.

Important Points:

Clinical Pearls:

Clinical Pitfalls:

Introduction

Peripheral subcutaneous stimulation (PSS) is a new and exciting area of neurostimulation. It belongs to the general category of stimulation of the peripheral nervous system. However, instead of stimulating a well-defined nerve trunk, the stimulation is applied to the small terminal branches of one or more peripheral nerves. The target area for the stimulation is the subcutaneous tissue, where the small nervous endings of the nerves arborize in a widespread network.

The technique is known with several different names, such as subcutaneous stimulation, peripheral nerve field stimulation, regional stimulation, and peripheral nerve stimulation.16 All of these definitions point to the fact that the target is the small peripheral nervous system fibers in the subcutaneous tissue. This is a paradigm switch from previous neurostimulation modalities, in which the stimulation is applied to a well-defined large neural structure (i.e., a large peripheral nerve, the nerve roots, or the spinal cord).

Although the mechanisms of action are unknown, they are most likely similar to the ones described for peripheral nerve stimulation.7

This technique has determined a revolutionary change in the paradigm of classical neurostimulation as it has been performed for several decades. In the classical neurostimulation paradigm, the goal is to stimulate some major nervous sensory structures upstream from the painful area to generate paresthesias in that area. With PSS the lead is actually placed within or near the area of the pain (or the area of the projection of the pain). This technique was developed with the goal of stimulating areas that are notoriously difficult or impossible to reach from the spinal cord or major nerve trunk level, including the posterior axial surface of the body from the neck to the lumbar spine. Although originally developed for these difficult situations, PSS is sometimes being used as a first, minimally invasive, neurostimulation procedure if the pain is limited to a relatively small and well-defined area.