Clinical phenotypes and outcomes of spinal cord stimulation in painful peripheral polyneuropathy: a cohort including diabetic, chemotherapy-induced, and idiopathic etiologies

Background and objective Chronic painful peripheral polyneuropathy (PPN) is a leading global cause of chronic pain and may arise from a wide range of etiologies. When pharmacological treatments fail to provide adequate pain relief, spinal cord stimulation (SCS) has demonstrated efficacy in selected subtypes. This study investigated the effectiveness of SCS in alleviating pain, neurological symptoms and signs, and other health-related outcomes in patients with diverse forms of PPN, including diabetic (DPN) and chemotherapy-induced (CIPN) peripheral neuropathies, and chronic idiopathic axonal polyneuropathy (CIAP). Methods This prospective, single-center observational study included 30 patients with drug-refractory PPN (11 DPN, 8 CIPN, 9 CIAP, and 2 other etiologies: 1 amyloidosis and 1 Fabry disease). All patients were implanted with two percutaneous leads at T10–T11 targeting lower limbs; a cervical lead (C4–C7) when upper limb pain was present; and SCS system. Low-frequency (<100 Hz) sub-perception and/or supra-perception stimulation modalities were offered. Clinical outcomes were assessed at baseline and at 2, 4, 6, and 12 months post-implantation and included pain (VAS, SF-MPQ-2), neuropathic symptoms (NPSI), autonomic symptoms (SAS), neurological signs, and other health-related factors. Intraepidermal nerve fiber density (IENFD) was assessed at baseline and at 12 months. Results Baseline evaluations demonstrated severe disease burden, with CIAP patients exhibiting more pain symptoms and DPN patients more neurologic deficits. SCS produced a significant and sustained reduction in pain intensity and symptoms (VAS from 8.6 to 2.0, SF-MPQ-2 from 115.5 to 23.0; p < 0.001) across all PPN subtypes, with greater improvements observed in DPN ( p < 0.001). Additional benefits included reductions in neuropathic symptoms (NPSI from 61.1 to 11.1; p < 0.001), autonomic symptoms (SAS from 16.5 to 9.9; p = 0.02) and improvements in sleep, functioning, and quality of life (EQ-VAS from 38.8 to 77.9; p < 0.001). Neurological signs remained unchanged. Use of analgesics decreased substantially (59% complete withdrawal; 41% partial), and 96% of patients reported “much” or “very much” improvement. Twelve-month IENFD measurements showed a lower-than-expected mean decline across etiologies, with IENFD increases outnumbering decreases, although the changes were modest. Discussion SCS was associated with substantial and durable improvements in pain, neuropathic and autonomic symptoms, and other wellbeing outcomes across multiple painful PPN etiologies. The IENFD results suggest that SCS may have some effects on small-fiber integrity.