Submitted by Jeff Sung
Title: Treatment Strategies and Effective Management of Phantom Limb–Associated Pain.
Background: I recently had an inpatient consult for a young patient with renal failure, severe extensive peripheral vascular disease, chronic pain, and gangrene of the foot requiring amputation. Not only did the patient want to refuse amputation, she was also highly concerned about uncontrolled pain in the leg, both before and after surgery. Pain management was extremely difficult due to high opioid requirements balanced against oversedation and the consideration of phantom limb pain (PLP) post-op. I wondered what the current literature says about PLP and its treatment.
Design and Participants: This article is a comprehensive review of the literature on the prevalence, diagnosis, presentation, clinical implications, and treatment of PLP.
Results: Limb amputation has been a part of medicine for 45,000 years and PLP has been described since the American Civil war. Currently, PLP affects anywhere from 40-80% of amputees. Its pathogenesis is unclear and its presentation can vary widely. 50% of patients report PLP within 24 hours post-op and 85% within 1 week. However, PLP can also present years later and often becomes a chronic condition. Psychiatric illness such as depression, anxiety, and mood disorders have a higher prevalence in amputees than in the general population and increase with PLP. Quality of life is rated lower in patients with PLP than those who do not experience PLP post-amputation. Pharmacologic treatment is first line therapy with agents such as gabapentin, amitriptyline, opioids, and local anesthetics. However, many patients’ pain is refractory to pharmacologic agents. Non-invasive treatment options include sensory motor training, mirror visual therapy, non-invasive neuromodulation, and virtual reality. The most promising of these are mirror therapy and virtual reality (both utilize the same mechanism but virtual reality is more immersive). Invasive options are considered last resort; these include spinal cord stimulation, dorsal root ganglion stimulation, and peripheral nerve stimulation. Studies including treatment for concomitant depression showed improved results. Although there have been good results in case series, retrospective reviews, and case studies, high quality controlled trials are lacking.
Commentary: Considering the long history of limb amputation and the high prevalence of PLP, there is surprisingly limited knowledge and research on this condition. The exact pathogenesis is still undefined; it is likely multi-factorial. Presentation and timing vary widely. Combined treatment strategies have led to mixed results and varied efficacy making standardized treatment difficult to find. Pharmacologic and non-invasive treatments remain first line with invasive surgical options reserved as last resort. Psychologic treatment must also be considered. Good quality randomized controlled studies on treatments are sorely lacking. Further research is clearly indicated for this prevalent and complex but poorly understood and debilitating condition.
Bottom Line: PLP is poorly understood and good quality research is lacking. The current recommendation is for pharmacologic and non-invasive treatments followed by surgical interventions for refractory cases.
Source: The reference for the article in AMA style Urits I, Seifert D, Seats A, Giacomazzi S, Kipp M, Orhurhu V, Kaye AD, Viswanath O. Treatment Strategies and Effective Management of Phantom Limb-Associated Pain. Curr Pain Headache Rep. 2019 Jul 29;23(9):64. doi: 10.1007/s11916-019-0802-0. PMID: 31359171.
