Continuous Peripheral Nerve Block With Ropivacaine Improves Phantom Limb Pain

A continuous peripheral nerve block with ropivacaine increased the likelihood of clinical improvement in pain intensity among patients with mild to moderate postamputation phantom limb pain. These were the findings of a study published in the journal Regional Anesthesia Pain Medicine.

In a previously published clinical trial (ClinicalTrials.gov Identifier: NCT01824082), the PAINfRE investigators found that a 6-day continuous peripheral nerve block reduced established postamputation phantom pain. However, in an effort to provide both patients and providers with the best information to make treatment decisions, they conducted a reanalysis of their published data for this study that would better reflect a patient’s perspective.

Patients (N=144) with limb amputation who were experiencing phantom pain were randomly assigned to receive continuous peripheral nerve block with ropivacaine (n=71) or saline (n=73) for 6 days. The outcomes of interest in this analysis were clinical improvement, defined as a 1.5-point or greater improvement on the 7-point ordinal Patient Global Impression of Change (PGIC) scale. Mild pain was defined as a numeric rating scale (NRS) score of less than 5 points, moderate pain was defined as a NRS of 5-7 points, and severe pain was defined as a NRS of greater than 7 points.

More than half of patients who received active treatment (57%) reported a 2-point or greater improvement in NRS score at 4 weeks compared with a 26% improvement in average pain (relative risk [RR], 1.6; 95% CI, 1.2-2.1; P <.001) and 25% improvement for worst pain (RR, 1.8; 95% CI, 1.3-2.7; P <.001) among saline recipients.

A significantly greater proportion of ropivacaine recipients reported a clinically relevant improvement in average (49% vs 21%; P <.001) and worst (48% vs 21%; P <.001) pain compared with control individuals, respectively. According to the PGIC, 53% of ropivacaine recipients compared with 30% of placebo recipients rated their pain as improved at 4 weeks (P =.008).

Stratified by the level of pain at baseline, however, a 28% improvement in average phantom pain was observed among more ropivacaine recipients compared with placebo recipients for those with mild (48% vs 22%) or moderate (59% vs 28%) pain at baseline and not among those with severe pain (50% vs 43%), respectively. Similar trends in residual limb pain were observed.

These findings were potentially limited, as the researchers noted that although patients were supposed to distinguish phantom from residual limb pain, some responded to questions about their general pain.

The researchers concluded, “[A] continuous [peripheral nerve block] more than doubles the chance of a clinically relevant improvement among patients with postamputation phantom and/or residual limb pain. Patients with postamputation pain rate analgesic improvements as clinically relevant similarly to other chronic pain etiologies[.]”

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.