Botulinum Toxin Type A for Lumbar Sympathetic Ganglion Block in Complex Regional Pain Syndrome: A Randomized Trial

Abstract

Background The present study was designed to test the hypothesis that botulinum toxin would prolong the duration of a lumbar sympathetic block measured through a sustained increase in skin temperature. The authors performed a randomized, double-blind, controlled trial to investigate the clinical outcome of botulinum toxin type A for lumbar sympathetic ganglion block in patients with complex regional pain syndrome. Methods Lumbar sympathetic ganglion block was conducted in patients with lower-extremity complex regional pain syndrome using 75 IU of botulinum toxin type A (botulinum toxin group) and local anesthetic (control group). The primary outcome was the change in the relative temperature difference on the blocked sole compared with the contralateral sole at 1 postoperative month. The secondary outcomes were the 3-month changes in relative temperature differences, as well as the pain intensity changes. Results A total of 48 participants (N = 24/group) were randomly assigned. The change in relative temperature increase was higher in the botulinum toxin group than in the control group (1.0°C ± 1.3 vs. 0.1°C ± 0.8, respectively; difference: 0.9°C [95% CI, 0.3 to 1.5]; P = 0.006), which was maintained at 3 months (1.1°C ± 0.8 vs. –0.2°C ± 1.2, respectively; P = 0.009). Moreover, pain intensity was greatly reduced in the botulinum toxin group compared with the control group at 1 month (–2.2 ± 1.0 vs. –1.0 ± 1.6, respectively; P = 0.003) and 3 months (–2.0 ± 1.0 vs. –0.6 ± 1.6, respectively; P = 0.003). There were no severe adverse events pertinent to botulinum toxin injection. Conclusions In patients with complex regional pain syndrome, lumbar sympathetic ganglion block using botulinum toxin type A increased the temperature of the affected foot for 3 months and also reduced the pain. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Agents Used for Nerve Blocks and Neurolysis

“…45 The agent of choice is 2 to 3 mL of absolute ethanol, but 3 mL of phenol 7% has been used; other options include botulinum toxin, RFA, and laser ablation. 67 68 69 70 71 In one head-to-head study, it was noted that RFA resulted in fewer instances of post-sympathetic neuralgia compared with ethanol, but also a significantly decreased rate of efficacy at 8 weeks. 72 The procedure has been shown to produce favorable results with cutaneous hyperemia in the lower extremities sometimes occurring immediately afterward due to the resulting vasodilation.…”

Prolonging Sympathetic Blockade for Complex Regional Pain Syndrome: Is Botulinum Toxin the Answer?

“…While conceptually appealing and grounded in basic science studies demonstrating the potential for sympathectomy to alleviate neuropathic pain, 6 the study design from Yoo et al raises as many questions as it answers. 4 The authors chose temperature change as the primary outcome measure "…lumbar sympathetic blocks with botulinum toxin could be a therapeutic alternative for patients with complex regional pain syndrome. "…”

“…In their study, Yoo et al used relatively low local anesthetic volumes (a total of 3 ml) at two different spinal levels as a selection criterion for enrollment. 4 However, the volumes of botulinum toxin injected (8 ml), though less than volumes used in some clinical studies and practices, 1,9,11 were several-fold greater than those used for the "screening" blocks, which undermines specificity. Given the potentially catastrophic consequences of extravasation of botulinum toxin onto nerves and muscles near the stellate and lumbar sympathetic ganglia (e.g., dysphagia, hoarseness, weakness) and the wide variations in anatomy, 19,20 greater precision would be needed for widespread use in clinical practice.…”

“…While conceptually appealing and grounded in basic science studies demonstrating the potential for sympathectomy to alleviate neuropathic pain, 6 the study design from Yoo et al raises as many questions as it answers. 4 The authors chose temperature change as the primary outcome measure to ascertain whether botulinum toxin might prolong temperature increase (technical success); however, studies have not found a meaningful correlation between temperature rise and pain relief (clinical success). 1,7 Since the goal of sympathetic blocks in complex regional pain syndrome is to reduce pain and not elicit temperature increase (though this may alleviate long-term trophic changes such as skin and nail changes that occur secondary to diminished regional blood flow and nutrition), the primary outcome measure essentially represents a surrogate outcome.…”

“…14 In a small (n = 9) double-blind, crossover study, Carroll et al found that adding botulinum toxin to bupivacaine resulted in longer pain relief than bupivacaine alone. Although temperatures were not measured in this study, unlike the study by Yoo et al ., 4 this was an enriched population that had previously responded to lumbar sympathetic blockade, making the crossover design more powerful.…”