Subcutaneous Target Stimulation-Peripheral Subcutaneous Field Stimulation in the Treatment of Refractory Angina: Preliminary Case Reports

Peripheral subcutaneous field stimulation for the treatment of spinal cord injury at-level pain: case report, literature review, and 5-year follow-up

Spinal cord injury (SCI) frequently engenders chronic pain which may be classified as occurring above, at, or below the level of injury. Since patients with SCI may have a complex combination of nociceptive and neuropathic pain, pharmacological interventions often fail. Peripheral subcutaneous field stimulation (PSFS) is a novel neuromodulation surgery for pain in which subcutaneous electrodes designed for spinal cord stimulation are placed subcutaneously in a region of pain. We report the case of a 26-year-old man who was an unrestrained driver in a motor vehicle accident and suffered a complete ASIA A spinal cord injury with paraplegia due to a T4 three-column burst fracture. He underwent successful surgical fixation of the fracture (7/27/12) and developed severe at-level SCI-associated pain which failed all conservative measures. After a successful trial, two octrode leads (Abbott Medical, Plano, TX, USA) were placed for PSFS under general anesthesia and were connected to a right flank rechargeable pulse generator (11/6/13). At 60 months postoperative, the patient continues to use the peripheral field stimulation system on a daily basis and reports near complete relief of his at-level spinal cord injury pain. He noted instantaneous relief of his pain once ideal stimulation programming was achieved and has tolerated complete cessation of all narcotic use. His current programming settings are: Frequency of 50 Hz (Hz), Pulse Width of 350 μs (μsec), Amplitude of 0.00 miliamps (mA), Comf of 7.70 mA, and Perc of 4.50 mA. Chronic pain is a challenging and expensive sequela to manage in SCI patients and newer therapies are needed. Our case suggests that SCI at-level pain may respond durably to PSFS and provides the longest published follow-up on a case of PSFS. Peripheral subcutaneous field stimulation remains an investigational treatment for chronic pain syndrome and larger, long-term follow up studies are needed for the FDA and payers to approve this modality.

The Effect of Peripheral Neuromodulation on Pain From the Sacroiliac Joint: A Retrospective Cohort Study

OBJECTIVE

To report a retrospective review of the longer-term results of peripheral neuromodulation in 12 patients with significant chronic sacroiliac joint pain who had previously failed multiple conservative and interventional pain therapies.

METHODS

To allow for the assessment of meaningful longer-term outcome, implants for all 12 patients had been in place for a minimum of 18 months to a maximum of 36 months prior to the formal review.

RESULTS

Compared to the preimplantation baseline, the longer-term follow-up revealed a significant and sustained reduction in visual analog scale pain scores from 8.7T 1.1 to 1.1T 1.0 (p < 0.001), with a 75% reduction in analgesia requirement, and improvement in pain impact on daily function from 94.1% T 5.9% to 5.8% T 6.0% (p < 0.001).

CONCLUSION

This initial case series has highlighted that SIJ neuromodulation results in the reduction in pain intensity and improved functionality in patients who have already failed conventional medical management and interventional techniques, including RF denervation. These preliminary results merit a prospective randomized trial of peripheral neuromodulation.

The Effect of Peripheral Neuromodulation on Pain from the Sacroiliac Joint: A Retrospective Cohort Study

We report here a retrospective review of the longer-term results of peripheral neuromodulation in 12 patients with significant chronic sacroiliac joint pain who had previously failed multiple conservative and interventional pain therapies. To allow for the assessment of meaningful longer-term outcome, implants for all 12 patients had been in place for a minimum of 18 months to a maximum of 36 months prior to the formal review. Compared to the preimplantation baseline, the longer-term follow-up revealed a significant and sustained reduction in visual analog scale pain scores from 8.7 ± 1.1 to 1.1 ± 1.0 (P < 0.001), with a 75% reduction in analgesia requirement, and improvement in pain impact on daily function from 94.1% ± 5.9% to 5.8% ± 6.0% (P < 0.001). These preliminary results merit a prospective randomized trial of peripheral neuromodulation.

Peripheral neuromodulation: a review

Peripheral nerve stimulation (PNS) is likely the most diverse and rapidly expanding area of neuromodulation. Its expansion has become possible due to both technological and clinical advances in pain medicine. The first implantable systems were surgically placed. However, it is currently commonplace to use percutaneous leads, as this approach has become instrumental in its expansion. The first percutaneous peripheral nerve stimulators were reported in 1999. Cylindrical leads were implanted to stimulate the greater occipital nerve to manage intractable headache. It has been expanded into other individual nerves or nerve plexuses to treat neuropathic, visceral, cardiac, abdominal, low back and facial pain. The use of PNS in modulating organ function in treatment of syndromes such as epilepsy, incontinence and obesity with vagal, tibial and gastric stimulation is under extensive investigation. New technologies that allow easier and safer electrode placement are expected to further expand the uses of PNS. A noninvasive stimulation will open this treatment modality to more clinicians of varying backgrounds.

Technological innovations in implants used for pain therapies

The field of pain management has experienced tremendous growth in implantable therapies secondary to the innovations of bioengineers, implanters, and industry. Every aspect of neuromodulation is amenable to innovation from implanting devices to anchors, electrodes, programming, and even patient programmers. Patients with previously refractory neuropathic pain syndromes have new and effective pain management strategies that are a direct result of innovations in implantable devices.