Covington, Stephen

Background Post-herpetic neuralgia (PHN) is a painful condition that presents after herpes zoster reactivation in the peripheral and central nervous system. When medical treatment fails, options are limited, and patients may suffer with chronic pain indefinitely. Case Presentation We present the case of a gentleman with a 3-year history of PHN in the distribution of the right lesser occipital and greater auricular nerves that failed to respond to medical treatment. He underwent a trial of neuromodulation, and post-operative pain scores improved by 80%, and at 60 days post-operatively his average pain score was 0 out of 10. Conclusions PNS is an effective and safe option for the treatment of chronic pain, and we present a report of successful treatment of PHN in a particularly difficult anatomic distribution. PNS of the lesser occipital and greater auricular nerves is a novel treatment for PHN and shows promise as an effective, safe therapy when other treatment fails.

Introduction Spinal cord stimulation is frequently used for the treatment of intractable chronic pain conditions. Trialing of the spinal cord stimulator device is recommended to assess the patient’s response to neurostimulation before permanent implantation. The trial response is often assessed by Numeric Rating Scale changes and patient-reported percentage pain improvement. Using number rating scale changes between prespinal and postspinal cord stimulation trial, a calculated percentage pain improvement can be obtained. The aim of this study was to assess the difference between calculated and patient-reported percentage improvement in pain scale during spinal cord stimulation trials. Methods This study was a retrospective single center review of all spinal cord stimulation trials from January 1 2017 to July 1 2019. A total of 174 patients were included. The paired t-test was used to compare numeric pain scores obtained prestimulation versus poststimulation. The mean difference between methods (patient-reported minus calculated) was compared with zero using the 1-sample t-test. Lin’s concordance correlation coefficient was computed with a 95% CI, calculated using Fisher z-transformation; and a bootstrapping approach was used to compare the concordance correlation coefficient between groups. In all cases, two-tailed tests were used with p<0.05 considered statistically significant. Results Based on prestimulation and poststimulation numeric rating scale scores, the mean±SD calculated percentage improvement in pain scale was 54±28. The mean±SD patient-reported percentage improvement in pain scale was 59±25. The overall 95% limits of agreement for the two methods are −30% to +41%. The overall concordance correlation coefficient was 0.76 (95% CI 0.69 to 0.81). Conclusion Although the two methods are highly correlated, there is substantial lack of agreement between patient-reported and calculated percentage improvement in pain scale, suggesting that these measures should not be used interchangeably for spinal cord stimulator trial outcome assessment. This emphasizes the need for improved metrics to better measure patient response to neuromodulation therapies. Additionally, patient-reported percentage improvement in pain was found to be higher than calculated percentage improvement in pain, potentially highlighting the multidimensional experience of pain and the unpredictability of solely using Numeric Rating Scale scores to assess patient outcomes.

Background The reported prevalence of chronic pain after spinal cord injury (SCI) varies widely due, in part, to differences in the taxonomy of chronic pain. A widely used classification system is available to describe subcategories of chronic pain in SCI, but the prevalence of chronic pain in SCI based on this system is unknown. Objective The primary objective of this systematic review and meta-analysis is to determine the prevalence of chronic pain after SCI based on the International Spinal Cord Injury Pain (ISCIP) classification system. Evidence review A comprehensive search of databases from January 1980 to August 2019 was conducted. The risk of bias was assessed using a modified tool developed for uncontrolled studies. The Grading of Recommendations, Assessment, Development and Evaluation approach was used to assess certainty in prevalence estimates. Findings A total of 1305 records were screened, and 37 studies met inclusion criteria. The pooled prevalence of overall chronic pain was 68% (95% CI 63% to 73%). The pooled prevalence of neuropathic pain in 13 studies was 58% (95% CI 49% to 68%); the pooled prevalence of musculoskeletal pain in 11 studies was 56% (95% CI 41% to 70%); the pooled prevalence of visceral pain in 8 studies was 20% (95% CI 11% to 29%) and the pooled prevalence of nociceptive pain in 2 studies was 45% (95% CI 13% to 78%). Meta-regression of risk of bias (p=0.20), traumatic versus non-traumatic etiology of injury (p=0.59), and studies where pain was a primary outcome (p=0.32) demonstrated that these factors were not significant moderators of heterogeneity. Certainty in prevalence estimates was judged to be low due to unexplained heterogeneity. Conclusion This systematic review and meta-analysis extends the findings of previous studies by reporting the prevalence of chronic pain after SCI based on the ISCIP classification system, thereby reducing clinical heterogeneity in the reporting of pain prevalence related to SCI.