Q) Since my friend had a below-knee amputation five months ago, she's been troubled by severe phantom-limb pain and itching where her lower leg once was. Doctors have prescribed drugs, which help, but the side-effects have stopped her from using them. Are there any effective alternative treatments available?-A.C., via e-mail
A) First described more than 500 years ago, phantom-limb pain (PLP) is the strange phenomenon of feeling pain in a limb that has been amputated. Although the limb is gone, the nerve endings at the site of the amputation continue to send signals to the brain that make it think that the limb is still there.
Almost all amputees feel at least some sort of sensation in the missing limb such as tingling, itching and heat or cold. But up to 80 per cent suffer actual pain-from throbbing and stabbing pain to cramping and burning-which can persist for years after the surgery (Lancet Neurol, 2002; 1: 182-9).
Although particularly common after amputation of an arm or leg, it can also occur with removal of other body parts-after mastectomy or tooth extraction, for example. Rarely, PLP has been reported in people born without limbs.
The precise cause of PLP remains unclear and it's notoriously difficult to manage. As one study noted,
"So far, none of the more than 40 treatment methods has proven to be really effective" (Zentralbl Chir, 2005; 130: 55-9). Even more shocking, a 2006 survey revealed that 53 per cent of patients with PLP-38 per cent of whom had severe pain-received no treatment whatsoever (Arch Phys Med Rehabil, 2006; 87: 270-7).
Pharmaceuticals are usually the first course of action for PLP sufferers, although there are no specific drugs for the condition. Your friend could have been prescribed anything from analgesics and opioids to antidep-ressants and anticonvulsants, all of which come with a truckload of side-effects-and may be no better thana placebo (Lancet Neurol, 2002; 1: 182-9).
Surgery is another option but, here again, results are generally disappointing (Br J Anaesth, 2001; 87: 107-16). However, a recent uncontrol-led study found that surgical treat-ment of the peripheral nerve was successful in reducing PLP in 14 of the 15 patients involved (Plast Reconstr Surg, 2006; 118: 1562-72). Deep brain stimulation also alleviated PLP-albeit in only three sufferers (J Clin Neurosci, 2005; 12: 399-404). Neverthe-less, it's clear that more research is needed. In the meantime, there are far less-invasive treatments on offer.
One of them is transcutaneous electrical nerve stimulation (TENS), a safe and painless technique that involves sending a weak electrical current to specific points on the skin overlying a nerve pathway. In a placebo-controlled study, TENS applied to the outer ear reduced PLP as well as non-painful phantom-limb sensations in amputees (J Pain Symptom Manage, 1991; 6: 73-83). In another trial, TENS took four weeks to work but, after four months, the treated patients reported signifi-cantly less PLP than the controls (J Bone Joint Surg Br, 1988; 70: 109-12).
Another promising treatment is acupuncture. Similar to TENS, elec-trical stimulation of acupoints was effective at reducing PLP by an average of 66 per cent in controlled studies (Pain, 1975; 1: 357-73). Tradi-tional needle acupuncture may also be beneficial (Minerva Med, 1979; 70: 3843-51; Arch Phys Med Rehabil, 1981;
62: 229-31). Needling of the residual limb according to Western medical acupuncture resulted in complete relief of PLP and other sensations in two out of three patients (Acupunct Med, 2004; 22: 93-7).
Another option to consider is Farabloc, a nylon and stainless-steel fabric that is meant to be worn over the site of amputation. The manu-facturer claims that it filters out harmful electromagnetic waves that aggravate the severed nerve endings. A study cited on their website (www.farabloc.com) has been pub-lished and, according to the results, it may be effective in reducing PLP (Can J Rehab, 1993; 6: 155-61).
Finally, there's evidence that 'rewiring' the brain can help to deal with the pain (see box).
Brain over pain
There is evidence to support the use of biofeedback, hypnosis and relaxation training in PLP (Appl Psychophysiol Biofeedback, 2005; 30: 83-93; Clin Rehab, 2002;
16: 368-77). One way these techniques may work is by reducing stress, thought to be a factor in PLP (J Psychosom Res, 1990; 34: 71-7). In one study of 16 PLP patients-two recent amputees and 14 with chronic pain-muscle-relaxation exercises combined with biofeedback resulted in virtually complete pain relief in more than half the participants. Moreover, these results were sustained for up to three years (Pain, 1979; 6: 47-55).
A particularly novel treatment for PLP is the use of a mirror box to produce the illusion of two healthy limbs. Using such visual feedback, the patient isable to 'move' the phantom limb and release it from a potentially painful position. Mirror-box therapy has proved useful for upper- and lower-limb amputees (Disabil Rehabil, 2004; 26: 901-4).
Similarly, virtual reality may combat PLP. UK scientists have reported that PLP may be relieved by attaching the real limb to an interface that allowedthe sufferer to see two limbs moving in a computer-generated simulation (Disabil Rehabil, 2007; 29: 1465-9).
These techniques may work by increasing a sense of control over the phantom limb which, in turn, rewires the brain. Indeed, amputees who used a fully functioning prosthesis on the affected limb showed significant reductions in PLP whereas the controls, wearing a cosmetic prosthesis with little functionality, showed no changes (Neurosci Lett, 1999; 272: 131-4).