Spinal Cord Stimulation in Patients with Diabetic Foot Disease: Prognosis Determined using Infrared Thermography as a Diagnostic Test
Authors: Bao Min , Zhang Mingjie , Qu Hongyu 
Published: October 2024

Objective
We aimed to determine whether perioperative infrared thermography (IRT) could be used as an index of success in the treatment of spinal cord stimulation (SCS) in patients with diabetic foot (DF) disease and in selecting suitable candidates for long-term SCS.
METHODS
Thirty-three patients with DF meeting our study inclusion criteria underwent permanent SCS implantation at the Shengjing Hospital of China Medical University from January 2021 to August 2023. Patients were grouped preoperatively based on the Wagner grading system for DF ulcers, and peripheral neuropathy was tested using a 10 g monofilament. The patients underwent temporary SCS following acompleting routine preoperative examination. IRT was performed preoperatively and at 1 week postoperatively, while lower limb skin temperature was recorded at multiple points and the mean value was calculated. During the temporary SCS test, patient pain was relieved satisfactorily; therefore, all patients subsequently underwent permanent SCS implantation and participated in a 6-month follow-up, with no complications leading to device removal. The patients were divided into two groups according to limb salvage status (treatment success group, no minor or major amputation during the follow-up postoperative period; treatment failure group, minor or major amputation performed during the follow-up period). To evaluate whether there were differences in patient baseline clinical data and the success rate of surgery according to different Wagner ulcer grades, a receiver operating characteristic curve was used to analyze the indicators of IRT. Logistic regression analysis was performed for large-fiber neuropathy, ulcer grade and the preoperative IRT.
RESULTS
All patients received permanent SCS and were followed up for 6 months. All patients had different degrees of pain relief (preoperative visual analog score [VAS], 6.82 ± 1.32; postoperative VAS, 5.48 ± 1.18; P < 0.001). Fifty-two limbs were salvaged during the follow-up period (SCS success rate, 78.8%). No significant difference in the SCS success rate in the affected limbs was observed between the different Wagner ulcer groups (P = 0.293). In the treatment success group, the mean preoperative IRT temperature was 31.35 ± 1.92°C, the mean postoperative IRT temperature was 31.99 ± 1.86°C, and the mean lower limb skin temperature increased by 0.65°C. In the treatment failure group, the mean preoperative IRT temperature in the lower limbs was 32.38 ± 2.25°C, and the mean IRT temperature at 1 week postoperatively was 31.69 ± 1.78°C, showing a decrease of 0.70°C. The SCS success rate was 59.1% in limbs with large-fiber neuropathy, and 88.6% in limbs without large-fiber neuropathy, and the difference was statistically significant (P = 0.007). We calculated the difference between perioperative IRT temperatures in the same limb and compared mean pre- and postoperative IRT temperatures. The diagnostic threshold for IRT alone was − 0.12°C, i.e., a -0.12°C increase postoperatively compared with preoperatively (positive predictive value, 91.84%; negative predictive value, 58.82%; AUCIRT, 0.79 [0.63–0.95], P < 0.001). Combined large-fiber neuropathy (P = 0.025) and the difference in perioperative IRT mean values (P = 0.001) were statistically significant for the diagnosis of SCS treatment results.
CONCLUSION
SCS treatment effectively relieved lower limb pain. Patients with DF and large fiber neuropathy had a lower surgical success rate, IRT was significantly higher in the treatment success group, and patients with peripheral neuropathy or a mean increase in perioperative lower limb IRT temperatures of < − 0.12°C were not suitable candidates for long-term SCS. IRT can be used as a diagnostic index for the prognosis of patients with DF receiving SCS and select suitable long-term SCS treatment candidates.