Quantitative assessment of painful diabetic peripheral neuropathy after high-frequency spinal cord stimulation: a pilot study.

OBJECTIVE: Randomized trials have demonstrated efficacy of spinal cord stimulation (SCS) for treatment of painful diabetic neuropathy (PDN). Preliminary data suggested that treatment of PDN with high-frequency SCS resulted in improvements on neurological examination. The purpose of the present study was to explore whether patients with PDN treated with high-frequency SCS would have improvements in lower-extremity peripheral nerve function. DESIGN: Prospective cohort study in an outpatient clinical practice at a tertiary care center. METHODS: Patients with PDN were treated with high-frequency SCS and followed up for 12 months after SCS implantation with clinical outcomes assessments of pain intensity, neuropathic symptoms, and neurological function. Small-fiber sudomotor function was assessed with the quantitative sudomotor axon reflex test (QSART), and large-fiber function was assessed with nerve conduction studies (NCS). Lower-extremity perfusion was assessed with laser Doppler flowmetry. RESULTS: Nine patients completed 12-month follow-up visits and were observed to have improvements in lower-extremity pain, weakness, and positive sensory symptoms. Neuropathy impairment scores were improved, and 2 patients had recovery of sensory responses on NCS. A reduction in sweat volume on QSART was observed in the proximal leg but not at other sites. No significant differences were noted in lower-extremity perfusion or NCS as compared with baseline. CONCLUSIONS: The improvement in pain relief was concordant with improvement in neuropathy symptoms. The findings from this study provide encouraging preliminary data in support of the hypothesis of a positive effect of SCS on peripheral neuropathy, but the findings are based on small numbers and require further evaluation. TRIAL REGISTRATION: ClinicalTrials.gov ID NCT03769675.

The Orthostatic Discriminant and Severity Scale (ODSS): an assessment of orthostatic intolerance.

PURPOSE: To assess the ability of the Orthostatic Discriminant and Severity Scale (ODSS) to distinguish symptoms of orthostatic intolerance from non-orthostatic symptoms. METHODS: Clinical evaluations and questionnaire responses were collected in 73 healthy controls and 132 patients referred to the Autonomic Disorders Clinic from September 1, 2016, through April 30, 2018, for queries regarding autonomic dysfunction. A receiver operating characteristic (ROC) curve analysis was used to interpret sensitivity and specificity and to determine cutoff scores for symptom assessment. Inter-item reliability was assessed using Cronbach's alpha. To calculate positive and negative predictive powers, patient data were collected in a single-blinded fashion where the researcher collecting questionnaire data was blinded to the clinical evaluation and diagnosis. Predictive powers were calculated using a chi-squared cross-tabulation. RESULTS: The orthostatic and non-orthostatic symptoms scores produced ROC curves with an area under the curve of 0.89 and 0.79, respectively. The orthostatic scores yielded a positive and negative predictive power value of 73% and 81%, respectively. Combined, the ODSS identified patients with and without orthostatic symptoms with an overall accuracy of 76%. The reliability of the ODSS was significant, with a Cronbach's alpha of 0.88, and all dichotomous items were deemed worthy of retention following an inter-item reliability assessment. CONCLUSIONS: The ODSS demonstrated a strong ability to distinguish patients with and without orthostatic intolerance and demonstrated sensitivity and specificity equivalent to that of other standardized measures. Overall, the ODSS produces symptom scores that are both reliable and useful for both research and clinical practice.