Phantomlimb pain:mechanisms and treatment approaches

Hindawi Publishing Corporation Pain Research and Treatment Volume 2011, Article ID 864605, 8 pages doi:10.1155/2011/864605

Review Article Phantom Limb Pain: Mechanisms and Treatment Approaches
Bishnu Subedi and George T. Grossberg
Department of Neurology & Psychiatry, Saint Louis University School of Medicine, St. Louis, MO 63104, USA Correspondence should be addressed to Bishnu Subedi,bsubedi@slu.edu Received 10 May 2011; Accepted 1 July 2011 Academic Editor: Bjorn A. Meyerson Copyright © 2011 B. Subedi and G. T. Grossberg. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The vast amount of research over the pastdecades has significantly added to our knowledge of phantom limb pain. Multiple factors including site of amputation or presence of preamputation pain have been found to have a positive correlation with the development of phantom limb pain. The paradigms of proposed mechanisms have shifted over the past years from the psychogenic theory to peripheral and central neural changes involving corticalreorganization. More recently, the role of mirror neurons in the brain has been proposed in the generation of phantom pain. A wide variety of treatment approaches have been employed, but mechanism-based specific treatment guidelines are yet to evolve. Phantom limb pain is considered a neuropathic pain, and most treatment recommendations are based on recommendations for neuropathic pain syndromes. Mirrortherapy, a relatively recently proposed therapy for phantom limb pain, has mixed results in randomized controlled trials. Most successful treatment outcomes include multidisciplinary measures. This paper attempts to review and summarize recent research relative to the proposed mechanisms of and treatments for phantom limb pain.

1. Introduction
The concept of phantom limb pain (PLP) as being thepain perceived by the region of the body no longer present was first described by Ambrose Pare, a sixteenth century French military surgeon [1]. Silas Weir Mitchell, a famous Civil War surgeon in the nineteenth century, coined the term “phantom limb pain” and provided a comprehensive description of this condition [2]. It continues to remain a poorly understood and difficult to treat medicalcondition. A recent study estimated that there were about 1.6 million people with limb loss in the USA in 2005 and this number was projected to increase by more than double to 3.6 million by the year 2050 [3]. Vascular problems, trauma, cancer, and congenital limb deficiency are among the common causes of limb loss. The number of traumatic amputations has also increased since the beginning of conflict inIraq and Afghanistan [4]. The incidence of PLP has been reported to range from 42.2 to 78.8% in patients requiring amputation [5–8]. Stump pain is described as the pain in the residual portion of the amputated limb whereas phantom sensations are the nonpainful sensations experienced in the body part that

no longer exists [6, 7]. Superadded phantom sensations are touch and pressure-like sensationsfelt on the phantom limb from objects such as clothing [9]. Risk factor for PLP are shown in Table 1. Recent studies report the prevalence of PLP to be more common among upper limb amputees than lower limb amputees. It was also reported to be more common among females than males [10, 11]. A survey reported greater overall average pain intensity and interference in females than males and femalesendorsed significantly greater catastrophizing, use of certain pain-coping strategies, and beliefs related to several aspects of pain resulting in poor adjustment [12]. Larger population studies are needed for more definite establishment of the risks associated due to the site of involved limb or gender of the patient in development of PLP. Phantom sensations and pain have been reported following...