Latest Findings on Phantom Limb Pain Treatment

Phantom limb pain (PLP) affects roughly 7 out of 10 amputees and is best managed using a combination of pharmacological and non-pharmacological treatments. The treatments prioritizing the removal of a neuroma — a scar tissue that typically develops after a nerve has been cut during amputation — are effective for managing neuroma-related phantom limb pain.

Key takeaways:
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    Non-pharmacological treatments are effective for managing phantom limb pain.
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    Treatments providing somatosensory feedback are effective for managing chronic phantom limb pain.
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    New surgical interventions show promising evidence for managing and preventing neuroma-related phantom limb pain.

On the other hand, treatments providing sensory and movement feedback to the amputated limb are effective for reducing chronic phantom limb pain — pain driven by functional changes in the brain.

Phantom limb pain treatments

Graded motor imagery (GMI) is a 6-week program involving a graded sequence of strategies, including left/right judgments, imagined movement exercises, and mirror therapy. Left/right judgments involve retraining the brain’s ability to judge a left limb from the right limb. These exercises are performed using a software application that displays photos representing an affected limb on the screen. The patient then chooses the sidedness of the presented photos by pressing either the left or right key on the screen (Figure 1). These exercises have been shown to address changes in the brain areas responsible for generating sensation.

phantom-limb-treatment-inovations

Imagined movement exercises involve imagining moving a limb from one position to another. These exercises have been shown to address changes in the brain areas responsible for planning movement. Mirror therapy involves hiding the phantom limb behind a mirror and moving the intact limb while viewing its visual reflection in the mirror. The important aspect of this treatment is moving the phantom limb together with the intact limb. The movement of the phantom limb has been shown to address changes in brain areas responsible for generating movement. The early evidence on graded motor imagery is promising, and patients have reported clinically meaningful pain reductions for up to six months. This treatment is non-invasive, affordable, and has no known adverse effects.

Virtual reality training is a computer-simulated training program that generates a virtual reflection of the intact limb, thus providing the user with an impression of having two functioning limbs. Virtual reality training has an advantage over mirror therapy because one can perform functional tasks and play games with the phantom limb. A head-mounted display (Figure 2) and virtual gaming software application are required for conducting this treatment.

vr-in-phantom-limb-treatment

Using a functional prosthetic limb providing somatosensory feedback has shown some evidence for reducing phantom limb pain in people with lower limb amputations. This type of prosthesis is equipped with sensors that generate sensations on the stump whenever the foot touches the ground. This sensory feedback is thought to improve the embodiment of a prosthesis, thus making it easy for patients to accept it as part of their body. However, a downside of this treatment is its inaccessibility for many patients due to the steep costs associated with getting a prosthesis.

More recently, non-invasive brain stimulation techniques are showing beneficial effects for reducing phantom limb pain, particularly transcranial direct current stimulation (tDCS) (Figure 3). Transcranial direct current stimulation involves stimulating the areas of the brain responsible for generating movement and sensation via electrodes placed on the head. Emerging evidence shows that tDCS is more effective when combined with other treatments, such as mirror therapy.

non-invasive-brain-stimulation-techniques

Targeted muscle reinnervation (TMR) is a surgical technique to treat neuroma-related phantom limb pain. The surgical technique involves cutting the neuroma off the sensory nerve, separating the small branch of a motor nerve, and joining the one branch of the separated motor nerve to the freshened sensory nerve. TMR aims to prevent the development of a neuroma usually responsible for phantom limb pain. This surgical procedure can be used to manage PLP in people with amputations. In addition, it can be conducted during an amputation of a limb to prevent the onset of PLP.

Transcutaneous electrical nerve stimulation (TENS) is another effective treatment for phantom limb pain, particularly in the early phase after amputation. TENS is delivered by a battery-powered device via electrodes positioned on the stump or along the distribution of the nerve that activates the painful area. The electrical stimulation is comfortable and below a threshold that would typically trigger pain. Instead, it feels like mild pins and needles or insects crawling on the skin. TENS is delivered for 30-60 minutes.

Where to get help for PLP

Most health professionals involved in pain management are trained in conducting these treatments. These health professionals include:

  • Physiotherapists
  • Occupational therapists
  • Physical Medicine and Rehabilitation Doctors
  • Physicians
  • Surgeons

A healthcare professional will typically conduct a thorough medical examination before conducting treatment. In some cases, a home treatment program will also be prescribed. Should other factors contribute to the pain (e.g., depression), the patient may be referred to a psychologist specializing in pain for additional treatment.

The current evidence on phantom limb pain management favors non-pharmacological treatments. Although each of the aforementioned treatments has some efficacy, greater pain reductions can be achieved when combined with other treatments, particularly those addressing psychosocial factors associated with pain. The current treatments for phantom limb pain have limited adverse effects. However, patients should consult their treating clinician should they experience unexpected symptoms, such as increased pain.

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