Correlation Between Temperature Rise After Sympathetic Block and Pain Relief in Patients with Complex Regional Pain Syndrome

Abstract

Objective Determine the correlation between post-sympathetic block pain temperature change, and immediate and intermediate-term pain relief. Design Retrospective analysis Setting Academic setting Subjects 79 pts with CRPS who underwent sympathetic block. Methods Pre- and post-block temperatures in the affected extremity, and pain scores immediately (based on 6-hour pain diary) post-block and at the intermediate-term 4–8-week follow-up were recorded. Post-block pain reductions of 30–49% and ≥ 50% were designated as partially sympathetically-maintained pain (SMP) and SMP. A decrease in pain score ≥ 2-points lasting ≥ 4 weeks was considered a positive intermediate-term outcome for sympathetic block. Results A weak correlation was found between immediate-term pain relief and the extent of temperature rise for the cohort (R = 0.192, P = 0.043). Greater immediate-term pain reduction was reported among patients who experienced ≥ 7.5° C temperature increase (mean 4.1, 95% CI [3.33, 4.76]) compared to those who experienced < 2° C (2.3, 95% CI [1.36, 3.31]) and ≥ 2° C x < 7.5° C (2.9, 95% CI [1.8; 3.9]; P = 0.036). The correlations between temperature increase and intermediate-term pain score reduction at 4–8 weeks (R = 0.052, P = 0.329), and between immediate and intermediate-term pain relief (R = 0.139, P = 0.119) were not statistically significant. Conclusions A weak correlation was found for those who experienced greater temperature increases post-block to experience greater immediate pain relief. Higher temperature increase cutoffs than are typically used may be necessary to determine whether a patient with CRPS has SMP.

Human lumbar sympathetic blockade: An anatomical study to address potential block failure

“…The trunk had a single sympathetic ganglion at each vertebral level on each side of the spine. The location of each sympathetic ganglion was not precisely the same at each vertebral level, and it differed among cadavers owing to the normal anatomical variability demonstrated by other authors (Samen et al, 2022; Van Eijs et al, 2012). Our findings agree with Datta and Pai (Datta & Pai, 2004).…”

“…More accurate direct measurements of sympathetic blockades, such as skin temperature and regional tissue blood flow change pre‐ and post‐block, would be preferable measurements. Some authors include skin temperature measurement pre‐ and post‐block as a guide to block success (Meier et al, 2009; Van Eijs et al, 2012), even though skin temperature increase after sympathetic block in these studies evidently did not correlate with pain (Samen et al, 2022; Van Eijs et al, 2012). Nevertheless, we propose that the apparent high failure rate stems from anatomical and pathophysiological issues.…”

Effect duration of lumbar sympathetic ganglion neurolysis in patients with complex regional pain syndrome: a prospective observational study

“…Some retrospective studies have found no correlation between pain relief following a sympathetic block and temperature increase in patients with CRPS. These studies examined the relationship between temperature increase and pain reduction immediately after a single LSGB, stellate ganglion block, or LSGN in patients with CRPS 12 , 26 . The results indicated a very weak correlation between temperature rise and immediate pain relief following the procedure, despite patients with larger temperature increases experiencing greater immediate pain relief.…”

Clinical results of lumbar sympathetic blocks in lower limb complex regional pain syndrome using infrared thermography as a support tool

“…Hence, Tran et al 37 described a direct relationship between the temperature increase and the relief of pain and allodynia. However, other authors deny this correlation 3,19,31,38 . Kim et al 14 validated the accuracy of thermography to confirm the success of LSBs.…”

“…However, other authors deny this correlation. 3,19,31,38 Kim et al 14 validated the accuracy of thermography to confirm the success of LSBs. In a preliminary study published by Cañada-Soriano et al, 44 LSBs were performed for the treatment of CRPS in lower limbs in 13 patients under radioscopic control and confirmation of block success by thermography.…”