Abstract

Background

This review is an update of a previously published review in the Cochrane Database of Systematic Reviews, 2005, Issue 4 (and last updated in the Cochrane Database of Systematic Reviews, 2013 issue 8), on local anaesthetic blockade (LASB) of the sympathetic chain to treat people with complex regional pain syndrome (CRPS).

Objectives

To assess the efficacy of LASB for the treatment of pain in CRPS and to evaluate the incidence of adverse effects of the procedure.

Search methods

For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 9), MEDLINE (Ovid), EMBASE (Ovid), LILACS (Birme), conference abstracts of the World Congresses of the International Association for the Study of Pain, and various clinical trial registers up to September 2015. We also searched bibliographies from retrieved articles for additional studies.

Selection criteria

We considered randomised controlled trials (RCTs) that evaluated the effect of sympathetic blockade with local anaesthetics in children or adults with CRPS compared to placebo, no treatment, or alternative treatments.

Data collection and analysis

We used standard methodological procedures expected by Cochrane. The outcomes of interest were reduction in pain intensity, the proportion who achieved moderate or substantial pain relief, the duration of pain relief, and the presence of adverse effects in each treatment arm. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created a 'Summary of findings' table.

Main results

We included an additional four studies (N = 154) in this update. For this update, we excluded studies that did not follow up patients for more than 48 hours. As a result, we excluded four studies from the previous review in this update. Overall we included 12 studies (N = 461), all of which we judged to be at high or unclear risk of bias. Overall, the quality of evidence was low to very low, downgraded due to limitations, inconsistency, imprecision, indirectness, or a combination of these.

Two small studies compared LASB to placebo/sham (N = 32). They did not demonstrate significant short‐term benefit for LASB for pain intensity (moderate quality evidence).

One small study (N = 36) at high risk of bias compared thoracic sympathetic block with corticosteroid and local anaesthetic versus injection of the same agents into the subcutaneous space, reporting statistically significant and clinically important differences in pain intensity at one‐year follow‐up but not at short term follow‐up (very low quality evidence).

Of two studies that investigated LASB as an addition to rehabilitation treatment, the only study that reported pain outcomes demonstrated no additional benefit from LASB (very low quality evidence).

Eight small randomised studies compared sympathetic blockade to various other active interventions. Most studies found no difference in pain outcomes between sympathetic block versus other active treatments (low to very low quality evidence).

One small study compared ultrasound‐guided LASB with non‐guided LASB and found no clinically important difference in pain outcomes (very low quality evidence).

Six studies reported adverse events, all with minor effects reported.

Authors' conclusions

This update's results are similar to the previous versions of this systematic review, and the main conclusions are unchanged. There remains a scarcity of published evidence and a lack of high quality evidence to support or refute the use of local anaesthetic sympathetic blockade for CRPS. From the existing evidence, it is not possible to draw firm conclusions regarding the efficacy or safety of this intervention, but the limited data available do not suggest that LASB is effective for reducing pain in CRPS.

Author(s)

Neil E O'Connell, Benedict M Wand, William Gibson, Daniel B Carr, Frank Birklein, Tasha R Stanton

Abstract

Plain language summary

Local anaesthetic sympathetic blockade for complex regional pain syndrome

Background

Local anaesthetic sympathetic blockade (LASB) is a common treatment for complex regional pain syndrome (CRPS). It involves blocking the activity of sympathetic nerves alongside the spine. The sympathetic nervous system mainly controls unconscious actions such as heart rate, blood flow, and perspiration. The injection of a local anaesthetic drug around the nerves temporarily blocks the function of the nerves. This updated review aimed to summarise the available evidence regarding whether LASB is effective at reducing pain in CRPS, how long any pain relief might last, and whether LASB is safe.

Key results and quality of the evidence

In September 2015, we found a limited number of small trials, all of which had design flaws. We did not find evidence that LASB was better than placebo in reducing pain, or that it provided additional pain relief when added to rehabilitation. While a number of small studies compared LASB to other treatments, most did not find that LASB was better. One small study found that injecting the thoracic (upper back) sympathetic nerves with local anaesthetic and steroid was better than injecting the same drugs just under the skin at one‐year follow‐up, but the study may have been prone to bias. Only six studies reported on the type and amount of side effects. These studies reported only minor side effects, but since some studies did not report this information we can draw no firm conclusions about the safety of LASB. The evidence was mostly of low or very low quality.

Overall, the evidence is limited, conflicting, and of low quality. While we cannot draw strong conclusions, the existing evidence is not encouraging.

Author(s)

Neil E O'Connell, Benedict M Wand, William Gibson, Daniel B Carr, Frank Birklein, Tasha R Stanton

Reviewer's Conclusions

Authors' conclusions 

Implications for practice 

For people with CRPS

LASB is a treatment that may be offered for CRPS to help reduce pain and other symptoms. There is a scarcity of published evidence and a lack of high quality evidence to support or refute its effectiveness, though the available evidence is not encouraging. Due to the scarcity of evidence it is not possible to draw confident conclusions about the safety of LASB. People should consider this information when deciding whether to agree to receive the treatment.

For clinicians

There is a scarcity of published evidence and a lack of high quality evidence to support or refute its effectiveness, though the available evidence is not encouraging. One study, judged to be at high risk of bias, provides very low quality evidence that LASB may reduce the risk of recurrence of pain when added to rehabilitation and standard pharmacological care, and one study, also judged to be at high risk of bias, suggests that thoracic sympathetic block with local anaesthetic and corticosteroid may be effective. However, on the basis of such evidence it is not possible to make any clinical recommendations. Due to the scarcity of evidence it is not possible to draw confident conclusions about the safety of LASB.There is currently little credible evidence to support the use of LASB for CRPS.

For policy makers and funders

The available evidence relating to the effectiveness of LASB for CRPS is not compelling. While there is substantial uncertainty regarding the effectiveness of alternative therapeutic options (O'Connell 2013), it is not clear that investment in this procedure provides clinical value.

Implications for research 

General

If LASB is to continue to be offered to people with CRPS, there is a clear need for further, better quality research into its efficacy. It seems likely that the best chance of delivering high quality trials is through multicentre, collaborative research projects that can recruit from larger clinical populations. While many studies investigate the effect of adding therapeutic agents to LASB, there remains substantial uncertainty regarding the efficacy of simple local anaesthetic blockade for CRPS.

Design

Reducing this uncertainty requires adequately powered trials that utilise placebo controls, ensure adequate blinding and confirm the technical adequacy of the block. Future trials should use established diagnostic criteria and clearly report the type of CRPS under investigation. Trials should also consider the IMMPACT recommendations for the design of trials in pain to ensure that outcomes, thresholds for clinical importance and study designs are optimal (Dworkin 2008; Dworkin 2009; Dworkin 2010; Turk 2008a; Turk 2008b).

Measurement (endpoints)

Future trials should measure both immediate pain relief and long‐term (≥ 6 month) outcomes from LASB. Furthermore, future trials should adhere to the CONSORT guidance on standards of reporting and should clearly report all adverse events (Altman 2012).

Get full text at The Cochrane Library