A Prospective Clinical Trial to Assess High Frequency Spinal Cord Stimulation (HF-SCS) at 10 kHz in the Treatment of Chronic Intractable Pain from Peripheral Polyneuropathy
Vincent Galan MD, MBA1; Paul Chang MD1; James Scowcroft MD2; Sean Li MD3; Peter Staats MD, MBA3, Jeyakumar Subbaroyan PhD4
1Georgia Pain Care, Stockbridge, GA; 2KC Pain Centers, Lee’s Summit, MO; 3Premier Pain Centers, Shrewsbury, NJ; 4Nevro Corp., Redwood City, CA
Peripheral neuropathy is caused by damage to or dysfunction of peripheral nerves, resulting in pain, numbness, and/or weakness. Damage may affect small (myelinated Aδ and unmyelinated C) fibers along with injury to large myelinated fibers. The goal of this study is to assess the safety and effectiveness of paresthesia-independent, high frequency SCS (HF-SCS) at 10 kHz in the treatment of chronic intractable pain from peripheral polyneuropathy.
Materials and Methods:
Subjects with chronic, intractable pain of ≥5 cm (on a 0-10 cm visual analog scale [VAS]) of the upper or the lower limb from peripheral polyneuropathy were enrolled in a prospective, multi-center study following Institutional Review Board approval. After obtaining informed consent, each subject was implanted with two epidural leads spanning C2-C6 or T8-T11 vertebral bodies for upper limb pain and lower limb pain, respectively. Subjects with successful trial stimulation (≥40% pain relief) were implanted with an implanted pulse generator (Senza system, Nevro Corp., Redwood City, CA). Safety and effectiveness endpoints were captured up to 12 months post-implant. Interim 6 month results are presented as mean ± standard deviation in the permanent implant population.
A total 28 subjects were enrolled in the study of whom two failed additional screening criteria. Majority of the subjects presented with lower limb pain (n=27). Common diagnoses include idiopathic polyneuropathy (n=16) and painful diabetic neuropathy (n=9).
Twenty two of the 26 subjects trialed had a successful trial (84.6% success rate). Three subjects declined to proceed to the permanent implant despite a successful trial. One subject was withdrawn by the study investigator. Five procedure related adverse events (AE) were reported (implant site infection: 1, pain in extremity: 1, implant site dehiscence: 1, implant site extravasation: 2).
Baseline pain scores of 7.6±1.4 cm (n=26) improved to 1.9±1.7 cm (n=18) and 2.3±1.8 cm (n=17) at 3 and 6 month follow-ups, respectively. Responder rates were 78% (14/18) and 76% (13/17) at 3 and 6 month follow-ups, respectively. In the painful diabetic neuropathy (PDN) sub-group, baseline pain scores of 7.9±1.2 cm (n=8) improved to 2.1±1.4 cm (n=7) and 1.9±1.3 cm (n=7) at 3 and 6 month follow-ups, respectively. Responder rate was 85.7% (6/7) at both time points. Thirteen subjects reported improvement in their neurological assessment (sensory: 13, reflex: 3) at 3 months.
Pain, as measured qualitatively by the Short-form McGill Pain Questionnaire (SF-MPQ-2), decreased from baseline in all pain sub- categories at 3 months (Figure 1).
Pain disability index (PDI) decreased from 40.3±17.2 (n=26) at baseline to 21.6±14.2 (n=17) and 19.1±16.3 (n=17) at 3 and 6 months post-implant, respectively. Subjects with at least a minimal clinically important difference (MCID) in PDI were 61% and 71% at 3 and 6 months, respectively.
Promising results from this study have led to initiation a randomized controlled trial for the treatment of painful diabetic neuropathy (PDN).