Subcutaneous Targeted Stimulation

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.

External Noninvasive Peripheral Nerve Stimulation Treatment of Neuropathic Pain: A Prospective Audit

BACKGROUND

Peripheral nerve stimulation (PNS) is a neuromodulation technique in which electrical current is applied to the peripheral nerves to ameliorate chronic pain through preferential activation of myelinated fibres, inducing long-term depression of synaptic efficacy. External noninvasive peripheral nerve stimulation (EN-PNS) is a novel and simple form of PNS that involves stimulation via an external nerve-mapping probe that is placed on the skin and connected to a power source.

OBJECTIVES

We aimed to assess the clinical utility of EN-PNS in patients with refractory neuropathic pains referred to a tertiary pain treatment center.

METHODS

We undertook a prospective audit of EN-PNS. Patients with a diagnosis of either complex regional pain syndrome or neuropathic pain after peripheral nerve injury who met inclusion criteria were included. Participants completed three stages of the audit: stage 1, six weekly outpatient treatment sessions; stage 2, six-week equipment home loan; stage 3, six weeks of no EN-PNS treatment. The primary outcome was the average post-treatment instantaneous pain intensity during the last week in stage 2 compared with baseline (11-point numerical rating scale).

RESULTS

EN-PNS provided significant short-term pain relief (n = 20 patients, average reduction of 2.8 numerical rating scale points, 95% CI 1.6-4.0, p < 0.001, intention-to-treat analysis). Eight patients (40%) improved in several outcome parameters ("responders"), including quality of life and function.

CONCLUSION

In this first prospective report on the use of EN-PNS in neuropathic pain, this technology provided significant clinical benefit for some patients. Controlled studies are required to confirm our results and the place of EN-PNS in future neuromodulation treatment algorithms. Given the refractory nature of these conditions, these results are encouraging.

Peripheral nerve stimulation for the treatment of postamputation pain--a case report

Many amputees suffer from postamputation pain, which can be extremely debilitating, decrease quality of life, increase the risk of depression, and negatively affect interpersonal relationships and the ability to work. Present methods of treatment, including medications, are often unsatisfactory in reducing postamputation pain. Electrical stimulation of the nerve innervating the painful area could reduce the pain, but peripheral nerve stimulation is rarely used to treat postamputation pain because present methods require invasive surgical access and precise placement of the leads in close proximity (≤ 2 mm) with the nerve. The present study investigated a novel approach to peripheral nerve stimulation in which a lead was placed percutaneously a remote distance (> 1 cm) away from the femoral nerve in a patient with severe residual limb pain (RLP) 33 years following a below-knee amputation. Electrical stimulation generated ≥ 75% paresthesia coverage, reduced RLP by > 60%, and improved quality of life outcomes as measured by the pain interference scale of the Brief Pain Inventory-Short Form (100% reduction in pain interference), Pain Disability Index (74% reduction in disability), and the Patient Global Impression of Change (very much improved) during a 2-week home trial. There were no adverse events. The ability to generate significant paresthesia coverage and pain relief with a single lead inserted percutaneously and remotely from the target nerve holds promise for providing relief of postamputation pain.