The following is a summary of “Evaluation of thoracic sympathetic ganglion block as a predictor for response to ketamine infusion therapy and spinal cord stimulation in patients with chronic upper extremity pain,” published in the May 2024 issue of Pain by Kim et al.

Researchers conducted a retrospective study to assess whether thoracic sympathetic ganglion block (TSGB) could predict treatment response to ketamine infusion therapy (KIT) and spinal cord stimulation (SCS) in patients with chronic upper-extremity pain, including those with complex regional pain syndrome (CRPS).

They defined positive outcomes for TSGB as a reduction of ≥ 2 on the 0–10 Numerical Rating Scale (NRS) score at 2 weeks post-procedure. Positive outcomes for KIT and SCS were determined by a reduction of ≥ 2 NRS score at 2–4 weeks post-KIT and a reduction of ≥4 NRS score at 2–4 weeks post-SCS implantation, respectively.

The results showed 207 patients who had TSGB, 38 underwent KIT, 34 had SCS implantation within 3 years post-TSGB, 33 received KIT, and 32 received SCS. Among the 33 patients who got KIT, 60.6% (n = 20) reported a ≥2 reduction in the 0–10 NRS pain score. Positive response to TSGB was observed in 70.0% (n = 14) of KIT responders, significantly higher than 30.8% (n = 4) of KIT non-responders. Multivariable analysis revealed a positive association between positive responses to TSGB and KIT (OR 7.004, 95% CI 1.26–39.02). Among the 32 SCS implantation patients, 68.8% (n = 22) experienced short-term effectiveness. Positive response to TSGB was significantly higher in SCS responders (45.5%, n = 10) than in non-responders (0.0%). However, no associations between pain reduction post-TSGB and post-KIT or post-SCS.

Investigators concluded that a positive response to TSGB emerged as a potential predictor of successful outcomes with KIT and SCS for patients with chronic upper-extremity pain, including CRPS.

Source: academic.oup.com/painmedicine/advance-article-abstract/doi/10.1093/pm/pnae038/7667915