Thoracolumbar Spinal Cord Stimulation

Abstract

Spinal cord (SC) stimulation is generally used as a last resort for patients who no longer have other treatment options. Typically, stimulators are used for patients who have undergone prior spine surgery with scarring. The best outcomes are achieved for patients with a larger component of neuropathic appendicular, as opposed to axial, pain. Other indications include complex regional pain syndrome, painful peripheral neuropathy, and phantom limb pain. In Europe, SC stimulation has been described for vascular claudication and angina.

Keywords

contralateral oblique, complex regional pain syndrome, failed back surgery syndrome, fluoroscopy, interlaminar, radicuolpathy, spinal cord stimulation

Note: Please see pages ii , iii for a list of anatomic terms/abbreviations used throughout this book.

Spinal cord stimulation (SCS) is generally used as a last resort for patients who no longer have other treatment options. Typically, stimulators are used for patients who have undergone prior spine surgery with scarring. The best outcomes are achieved for patients with a larger component of neuropathic, appendicular, as opposed to axial, pain. Other indications include complex regional pain syndrome, painful peripheral neuropathy, and phantom limb pain. In Europe, SCS has been described for treatment of vascular claudication and angina.

The technique described in this chapter follows the algorithm that has been described elsewhere in this book. In particular, we use a trajectory view, obliquing and tilting the fluoroscope to optimize the introducer needle entry point. Alternatively, one may count down and enter 1.5 to 2 pedicles below the target entry point, as demonstrated in Fig. 18.2 .

Note that the angle of the needle is much shallower (i.e., approaching as parallel as possible to the patient’s body) than that required for an interlaminar injection so that the stimulator lead will smoothly exit the needle into the posterior epidural space. The stimulator lead will ride along the patient’s midline until the electrodes reach the level at which the patient’s pain symptoms are covered, often between T7 and T8 for axial pain and between T8 and T10 for appendicular pain. Because we are using trajectory, contralateral oblique, and lateral safety views, it is not necessary to step off of the lamina with our described technique.

Trajectory View ( Fig. 18.1 )

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Confirm the targeted interlaminar space with the anteroposterior (AP) view. (See Fig. 18.1 ; T12-L1 is targeted here.)

Fig. 18.1

A, Fluoroscopic image of the trajectory view with the introducer tip in position over the T12-L1 interlaminar space. Note the very shallow tilt angle relative to the patient; this is a much more caudad tilt than would be used for a standard interlaminar epidural steroid injection. B, Radiopaque structures, trajectory view. C, Radiolucent structures, trajectory view.

Fig. 18.2

Alternate needle entry site (trajectory) in the anteroposterior (AP) view. In most individuals (normal body mass index [BMI]), the needle entry point is suggested to be one and half pedicle (P) distance from the T12-L1 disc space (or targeted intervertebral disc space). A, Fluoroscopic AP view showing the stimulator placement needle entering 1.5 pedicles (left L3) below the (T12-L1) target. There is a marker needle at T12 and another needle placed on the patient’s back so that it crosses the stimulator placement needle as it enters the skin. B, Corresponding diagram. In individuals with lower and higher BMIs, adjust the entry appropriately. This is to accommodate the decrease or increase in subcutaneous tissues between the skin surface and target.
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Pearl: The potentially safest needle entry point is at or below L2-L3 that is below the conus medullaris where the dura is more distensible, averting needle injury to the SC. This, of course, assumes there is no stenosis or other pathology at the entered level. However, the safety of entering at a lower level must be balanced with the need to navigate the lead further to the target location.
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Place a “marker” needle at one of the levels to assist counting in various views (left T12 pedicle in this example).
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With a radiopaque marker at the targeted level, tilt the C-arm image intensifier as caudally as possible while viewing the targeted interlaminar space to obtain the trajectory view. The amount of caudad tilt will be restricted by the patient’s body habitus, physically limiting the ability to tilt the image intensifier.
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Slightly oblique the C-arm contralateral to the introducer entry side so that the introducer will be set up to help guide the stimulator lead. The lead will have a tendency to travel contralateral to the side of entry, thereby making this technique an efficient method of facilitating proper lead positioning.
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Anesthetize the skin over the targeted interlaminar space, and use an 18-G, 1.5-inch needle to dilate the skin. Remove the 18-G needle, and use the introducer needle to obtain the trajectory needle view. Because this is the trajectory view, the needle entry position should be parallel to the C-arm beam. Note that the angle of the needle is as shallow as possible, as described in this chapter’s introduction ( Fig. 18.1 ).

There are typically no other radiolucent structures that are safety considerations in this trajectory view, besides advancing the needle too far ventrally. Other views should be used for needle advancement to best visualize the corresponding landmarks.

As an alternative to a direct trajectory view , one may instead choose the targeted interlaminar needle tip entry and enter the skin approximately 1.5 pedicles below it. For thinner patients (lower body mass index [BMI]) or larger patients (higher BMI), adjust the entry point accordingly ( Fig. 18.2 ). This alternate technique is especially helpful in situations when the intensifier cannot physically tilt enough because of the patient’s obesity or large buttock region.

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