Spinal Cord Stimulation

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Chapter 15 Spinal Cord Stimulation

Chul-Joong Lee, MD, PhD, Sang-Chul Lee, MD, PhD, Yong-Chul Kim, MD, PhD

Spinal cord stimulation (SCS) has been used for a wide variety of conditions (see later discussion of indications). The procedure is effective in patients who have chronic intractable pain of the trunk or limbs. Neuropathic pain responds well to SCS, whereas the procedure is usually ineffective in treating nociceptive pain and central pain. SCS has been used with increasing effectiveness because of improvements in patient selection criteria, lead placement accuracy, and devices (multipolar and multichannel). Studies have now shown that SCS is cost effective in comparison with conventional medical management, especially in the treatment of failed back surgery syndrome [1]. Kumar and associates [1], who conducted a 22-year study, reported effective long-term pain control, with a mean follow-up of 97.6 months, in 59.3% of all patients screened and 74.1% of the 328 patients in whom the hardware systems were internalized.

Treatment objectives

image To reduce rather than eliminate pain and diminish the use of opioids; 60% to 70% of patients may experience a 50% to 70% reduction in pain.
image To improve generalized well-being.
image To improve activity levels and degree of disability and to encourage greater independence.
image To improve the psychiatric symptoms, such as depression and anxiety, that frequently accompany chronic pain.

Indications

General considerations in the selection of SCS for a particular patient are as follows:

image More conservative therapies have failed.
image Pathology is the basis for the pain complaint.
image Further surgical intervention is not indicated.
image There is no serious untreated drug dependence problem.
image Psychological clearance has been obtained.
image There are no contraindications to implantation.
image Trial screening has been successful.
image The patient is able and willing to use the therapy.
image The patient understands the limits and risks of the therapy.

Special indications for this procedure include the following:

image Vascular pain: refractory angina and peripheral vascular disease
image Failed back surgery syndrome
image Spinal stenosis, nerve-root avulsion
image Complex regional pain syndrome type I or II
image Postherpetic neuralgia
image Phantom pain and stump pain
image Arachnoiditis
image Urologic diseases, such as interstitial cystitis and urge- incontinence
image Neuropathic perineal pain

Contraindications

Absolute contraindications to SCS are as follows:

image Sepsis
image Coagulopathy
image Previous surgery or trauma that has obliterated the spinal canal that the SCS lead would go into
image Local infection at the implantation site
image Presence of a demand pacemaker or implanted defibrillator

The following conditions are relative contraindications to SCS:

image Physical and/or cognitive disability that interferes with proper use of and understanding of the device
image Immunocompromise

Complications

Possible complications of SCS include the following [2–4]:

image Lead migration (3.8%-24%)
image Lead failure (7%)
image Pulse generator/receiver failure (2%)
image Epidural hematoma
image Infection
image Post–dural puncture headache
image Seroma (9%; spontaneously absorbed within 1-2 months) or stitch abscess
image Wound dehiscence
image Loss of pain relief
image Uncomfortable stimulation
image Cerebrospinal fluid leakage
image Paralysis (rare)
image Allergic response

Preoperative preparation

All patients should be screened by a psychologist before the trial implantation. Psychological screening includes the Minnesota Multiphasic Personality Inventory (MMPI) and a structured interview (past medical history, education, employment history, personal relationships, prior medical treatment, medication history, coping strategies, activity level, and pain severity). Patients who are approved for SCS should be educated about the system, its use, and the trial and implant procedures by means of printed materials or a video.

Radiologic anatomy

Figure 15-1 shows examples of the radiographic films that should be obtained in order to evaluate the following aspects of the thoracolumbar spine:

image Interlaminar space: to identify and mark vertebral segments for needle and lead placement
image Spinous process: to predict vertebral body rotation and place the lead on exact site
image Intervertebral foramen: to place the lead on the posterior epidural space
image

Figure 15–1 Anteroposterior (A) and lateral (B) images of the thoracolumbar spine.

Instrumentation

The following instruments and equipment are needed for a trial of SCS :

image Local anesthetics and antibiotics
image 25-gauge infiltration needle
image Syringes for infiltration of local anesthetics
image Trial screening kit, which consists of the following items:

Tuohy needle (Fig. 15-2)
Loss-of-resistance syringe
Guidewire (Fig. 15-2)
Trial screening lead (Fig. 15-3)
Anchors (Fig. 15-4)
Tunneling tool with a passing straw (Fig. 15-5)
Percutaneous extensions with plastic handle straw (Fig. 15-6)
Wrenches (Fig. 15-6)
Silicone boot (Fig. 15-6)
Screeners and screening cables (Fig. 15-7)

image

Figure 15–2 Tuohy needle (left) and guidewire (right).

image

Figure 15–3 Various types of leads for spinal cord stimulation.

image

Figure 15–4 Various types of anchors. (A) twist-lock, (B) three-wing (C) two-wing (D) EZ

image

Figure 15–5 Two kinds of tunneling tools. Top, A tunneling tool with a passing straw for trial stimulation. Bottom, An extension passer with an obturator for implantation of the pulse generator.

image image image

Figure 15–6 Various tools for percutaneous extension. A, Percutaneous extensions with or without plastic handle; B, wrenches; C, silicone boot.

image image

Figure 15–7 Screeners (A) and screening cables (B). Item on left side of each figure is that for trial stimulation and item on right side of each figure is that for pulse generator implantation (all manufactured by Medtronic, Inc, Minneapolis, MN).

The equipments for implantation of pulse generator are as follows:

image Local anesthetics and antibiotics
image 25-gauge infiltration needle
image Syringes for infiltration of local anesthetics
image Minor suture set
image Implantation kit, which consists of the following items:

Connecting cables to the pulse generator instrument
Extension passer with an obturator for pulse generator implantation (Fig. 15-5)
Extension for pulse generator implantation (Fig. 15-5)
Hex wrench and passing straw (Fig. 15-6)
Silicone boot (Fig. 15-6)
Pulse generator (Fig. 15-8)
Patient programmer for pulse generator (Fig. 15-9)

image

Figure 15–8 Pulse generators. (all manufactured by Medtronic, Inc, Minneapolis, MN)

image

Figure 15–9 Patient programmers for pulse generators. (all manufactured by Medtronic, Inc, Minneapolis, MN)

Procedure

Implantation of the Trial Lead

Preparation for Implantation of the Trial Lead

1. The patient’s written informed consent is obtained.
1. Place the patient in the prone position.
2. Place a pillow under the patient’s abdomen or chest to promote adequate forward flexion of the spine and to facilitate epidural lead placement.
3. Identify and mark vertebral segments for needle and lead placement (Table 15.1).
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