Spinal Cord Stimulator Implant (Neuromodulator) Revision for Failed Implant

Spinal cord stimulation (SCS) is an established clinical treatment for refractory chronic pain. Current implantation techniques for SCS are improving, and hardware and devices are highly structured and developed. However, revision of a spinal cord stimulator implant device may be necessary.

Revision of a spinal cord stimulator system is a minimally invasive procedure that is not an emergency surgery. In addition, stimulator system revision is not associated with morbidity. Repeated procedures, however, can expose patients to further complications, continued disability, and increase healthcare costs.

How Common is Revision Surgery?

Because spinal cord stimulation systems are a lifelong treatment, revision surgery is common. In a recent study involving 289 patients, hardware revision was required in 46% of the patients. Most complications are not life threatening, and are easily resolved with revision surgery. Avoidance of complications requires much vigilance, strict adherence of surgical techniques, and awareness.

Indications for Removal or Revision of a Spinal Cord Stimulator Implant (Neuromodulation)

The removal or revision of a spinal cord stimulator device is considered for any of the following indications:

• Loss of effectiveness
• Migration of leads
• Intolerance by the individual
• Infection
• Need for automatic implantable cardioverter defibrillator
• Painful generator site
• Development of neurological deficits
• Need for MRI test

Reasons for Spinal Cord Stimulator Implant Revision

Over time, percutaneous spinal cord stimulation leads can dislocate or have insulation failures. In addition, stimulation can be hindered by disconnection of the spinal cord stimulator lead. Other known causes of spinal cord stimulator failure involves fibrosis of a lead, dermatitis, effluence of cerebral spinal fluid (CSF), and meningitis (infection of the spinal cord and brain membranes).

Causes of Electrode Damage

Damage in the insulation coat of the lead occurs because the lead went through the needle, which is subjected to pressure and tension. The damaged insulator can cause short circuit and malfunction of a lead. In addition, repetitive straightening and folding of the lead can cause the lead to work like a hinge at the area of spinal movement. This reduces its surface area and can lead to pressure damage.

The Revision Procedure

Revision of a neuromodulation system is similar to the initial implant procedure. Depending on the circumstances, local or general anesthesia is used. First an incision is made over the back if the leads are the problem. Using radiographic guidance, the leads can be replaced or repositioned. If the electrical pulse generator is faulty, the surgeon will make an incision over the device and make repairs as necessary. The entire unit may need replaced, or the wires may require repair. After all revision is done, the incisions are closed using sutures.

Device-Related Complications

According to current research, more than one case of complications related to the stimulator device was found in more than 30% of patients. Causes of the problems were related to the:

• Insulator (24%)
• Electrode (7%)
• Battery (2%)
• Stimulator device (22%)
• Infection (8%)

Resources

Kim TH & Lee PB (2010). Spontaneous Lead Breakage in Implanted Spinal Cord Stimulation Systems. Kor J Pain, 23(1), 78-81.