Chapter 15 Spinal Cord Stimulation

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

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.

To improve generalized well-being.

To improve activity levels and degree of disability and to encourage greater independence.

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:

More conservative therapies have failed.

Pathology is the basis for the pain complaint.

Further surgical intervention is not indicated.

There is no serious untreated drug dependence problem.

Psychological clearance has been obtained.

There are no contraindications to implantation.

Trial screening has been successful.

The patient is able and willing to use the therapy.

The patient understands the limits and risks of the therapy.

Special indications for this procedure include the following:

Vascular pain: refractory angina and peripheral vascular disease

Failed back surgery syndrome

Spinal stenosis, nerve-root avulsion

Complex regional pain syndrome type I or II

Postherpetic neuralgia

Phantom pain and stump pain

Arachnoiditis

Urologic diseases, such as interstitial cystitis and urge- incontinence

Neuropathic perineal pain

Contraindications

Absolute contraindications to SCS are as follows:

Sepsis

Coagulopathy

Previous surgery or trauma that has obliterated the spinal canal that the SCS lead would go into

Local infection at the implantation site

Presence of a demand pacemaker or implanted defibrillator

The following conditions are relative contraindications to SCS:

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

Immunocompromise

Complications

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

Lead migration (3.8%-24%)

Lead failure (7%)

Pulse generator/receiver failure (2%)

Epidural hematoma

Infection

Post–dural puncture headache

Seroma (9%; spontaneously absorbed within 1-2 months) or stitch abscess

Wound dehiscence

Loss of pain relief

Uncomfortable stimulation

Cerebrospinal fluid leakage

Paralysis (rare)

Allergic response

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:

Interlaminar space: to identify and mark vertebral segments for needle and lead placement

Spinous process: to predict vertebral body rotation and place the lead on exact site

Intervertebral foramen: to place the lead on the posterior epidural space

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 :

Local anesthetics and antibiotics

25-gauge infiltration needle

Syringes for infiltration of local anesthetics

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)

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

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

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

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.

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

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:

Local anesthetics and antibiotics

25-gauge infiltration needle

Syringes for infiltration of local anesthetics

Minor suture set

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)

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

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).

4. Place the radiopaque pointer over the epidural entry location (just lateral to midline) at the target intervertebral space (Fig. 15-10); then mark this location on the patient’s skin with a sterile marker.

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