Clinical outcomes of spinal cord stimulation in patients with intractable leg pain in Japan

Background: Neuromodulation through spinal cord stimulation (SCS) is a therapeutic option for relieving leg pain and improving the chances of limb salvage in patients with intractable chronic limb-threatening ischemia (CLTI); however, there is no consensus on its indications.

Objective: The aim of this study was to assess the clinical outcomes of SCS in patients with intractable leg pain caused by various diseases treated in the department of cardiovascular medicine in Japan.

Methods: This was a retrospective study of patients who underwent SCS for pain management. Patients were considered eligible for the therapy if they met the following criteria: (1) intractable leg pain (numerical rating scale [NRS] score of 10), (2) no revascularization option, and (3) no septicemia.

Results: Twenty patients (mean age: 77 years; men/women: 11/9) were included in this study. The NRS score of the patients significantly reduced from 10 ± 0 before procedure to 4 ± 3 at discharge (p < 0.001). The clinical response rate of the entire cohort was 65% (13/20) at 17 ± 14 months after implantation; however, patients with intractable CLTI showed a low response rate (45%), whereas those with subacute limb ischemia showed a high response rate (100%). A multivariable regression analysis showed that hemoglobin level was significantly associated with treatment response, even after adjusting for age and sex (p = 0.026). The area under the receiver operating characteristic curve for the correlation between hemoglobin level (cutoff, 11.4 g/dL) and clinical response to SCS was 0.824 (0.619-1).

Conclusions: SCS can reduce clinical symptoms in majority of patients with intractable leg pain. Although implantation of an SCS device has been shown to improve microvascular perfusion insufficiency, the correlation between hemoglobin level and the clinical effect of SCS indicates that a preserved microcirculatory vascular bed is essential for the therapy to be effective.