A single lumbar sympathetic block may alleviate residual pain, phantom limb pain and perceived disability in patients with post-amputation pain, according to a case series published in Pain Medicine.
The case series included 4 patients selected from the Pathophysiology of Post-Amputation Pain study in which participants received either a single lumbar sympathetic block with 0.25% bupivacaine or sham needle placement for the treatment of post-amputation pain.
Investigators assessed pain with the numeric rating scale (NRS) and the McGill Pain Questionnaire-Short Form, pain and anxiety with the Center for Epidemiological Studies Depression Scale and Pain and Anxiety Symptoms Scale-short version, and disability with the Pain Disability Index (PDI). Psychophysical and biometric assessments were conducted using vibration sensation testing, brush sensation testing, thermal quantitative sensory testing, pinprick sensation testing, and the Von Frey repeated weighted pinprick sensation were also used to measure outcomes.
Patients 1 and 2 presented with a right transfemoral amputation secondary to peripheral vascular disease and were experiencing phantom and residual limb pain for 4 years and 2 years, respectively. Patients 3 and 4 underwent transtibial amputation and had been experiencing phantom and residual limb pain for 26 and 4 years, respectively. Patients 1 and 4 received a lumbar sympathetic block and patients 2 and 3 received a sham block.
Patients receiving the lumbar vs sham block reported reductions in phantom and residual limb pain at 3 months after treatment with the NRS and McGill Pain Questionnaire. Perception to light touch — assessed with the von Frey test — and depression were improved in all 4 patients. The lumbar sympathetic vs sham block also improved perceived disability at 3-month follow-up. Patients who received the sham block also reported clinically significant reductions in NRS immediately following injection, but these effects were not sustained.
In future studies, the investigators suggest assessing “distal limb surface temperature immediately pre- and post-lumbar sympathetic block in order to confirm appropriate sympathetic blockade, but also, measurement of this temperature change may be considered in the sham group in order to determine if dry needling or another sham intervention results in similar physiologic effects.”
McCormick ZL, Hendrix A, Dayanim D, et al. Lumbar sympathetic plexus block as a treatment for postamputation pain: methodology for a randomized controlled trial [published online March 8, 2018]. Pain Med. doi:10.1093/pm/pny041