Psychophysical and Functional Outcomes in Chemotherapy-induced Peripheral Neuropathy After Spinal Cord Stimulation: A Narrative Review and Case Series

Objectives: Chemotherapy-induced peripheral neuropathy (CIPN) is a complication that may occur after treatment with various anticancer drugs. In refractory CIPN cases, spinal cord stimulation (SCS) has garnered increased attention. The use of gait analysis and psychophysical quantitative sensory testing (QST) as an objective measurement of CIPN-related damage has burgeoned; however, these changes have not been reported for patients with CIPN after SCS implantation using either burst or tonic stimulation. Materials and Methods: This manuscript encompasses two parts: 1) a presentation of pain improvement in a series of patients who underwent tonic vs burst SCS for CIPN measured by gait and QST analysis and 2) a narrative review on gait and psychophysical QST outcomes between burst and tonic SCS stimulation pertaining to pain and the extrapolation to CIPN-related sequalae. Results: In these cases, gait scores improved in both patients. Touch thresholds were higher before SCS whereas skin temperatures were lower at the dorsal foot, subtalus, and posterior calf. Sharpness detection was drastically improved after SCS. In the review, the patients aligned with pain relief, suggesting good response to interventional outcomes with SCS. QST outcomes, particularly touch, sharpness, heat, and cold stimuli, however, were not fully corroborated. Similarly to other non-CIPN SCS gait studies, both tonic and burst studies provided positive outcomes on spatiotemporal gait parameters, gait form, and standardized gait scales. Conclusion: We emphasize the use of different SCS waveforms as a therapy for CIPN management and the use of psychophysical testing as a measure for diagnosis and monitoring CIPN's progress in our case series and review.