Phantom Pain

Phantom pain can be explained as the perception of shooting, stabbing or burning pain experienced by amputees in the missing limb or phantom limb. Even after the removal of the limb, the person continues to have sensations in the lost limb and tends to feel the presence of the lost limb.

Although the phantom limb is just a perception, the pain experienced is real and is usually accompanied by other health issues such as insomnia, anxiety, depression and an overall decline in quality of life of the patient.

What causes Phantom Pain?

Initially, it was thought that nerve cells linked to the amputated limb are destroyed following amputation. The sensations of phantom pain at the amputation site were believed to be due to the irritation of nerve endings present near the stump.

However, advances in imaging techniques and the development of magnetic resonance imaging and positron emission tomography enabled greater understanding of the phenomenon. Using these techniques, scientists could visualize increase in brain cortex activity when the patient experiences phantom pain.

Neurons in the brain were stimulated when the patients moved the stump of the lost limb. Scientists were surprised to see that stimulation was also possible by movement of body parts located near the missing limb.

Although the exact cause of phantom pain is still not clear, scientists have found that nerve cells in the brain rewire themselves following amputation so as to adapt to the changes in the body. Often, the brain continues to receive signals from the nerve endings that originally carried signals to and from the missing limb. This causes a signal conflict in the brain which causes a massive restructuring of sensory information.

What does Phantom Pain feel like?

Phantom pain is usually experienced as a sharp pain originating from the lowest part of the stump of the missing limb. It can sometimes feel like an electric shock or burning sensation. Some people feel a tingling sensation or numbness in the phantom limb.

The pain can start slowly and vary in intensity in different patients. It can last a few minutes to hours and in worst cases for a few days. Stump pain is similar to phantom pain, but is mostly felt in the stump.  Phantom pain can be devastating, with grave psychological effects leading to sleeplessness, anxiety and depression.

Treating Phantom Pain

Treatment methods for phantom pain include the use of analgesics such as narcotics, aspirin, and acetaminophen; antidepressants such as bupropion and imipramine; sedative-hypnotics such as benzodiazepines; and anticonvulsants such as gabapentin. These pills usually have adverse side effects.

The following coping techniques have been found to be helpful in some cases:

• Psychological counseling
• Meditation,
• Hypnosis
• Biofeedback
• Muscle relaxation.

The use of non-invasive treatments such as shock therapy, acupuncture, and transcutaneous electrical nerve stimulation is also common. In case non-invasive therapies fail to work, spinal cord stimulation, intrathecal drug delivery systems and deep brain stimulation are used to relieve phantom pain.

Recently, a product called Farabloc was developed for relief from intermittent phantom limb pain. According to a study published in Canadian Journal of Rehabilitation, Farabloc has an array of ultrathin steel threads woven into a linen fabric in a particular pattern. It can be sewn into a sleeve, vest, glove, or sock which can then be worn over the stump.

When a patient wears Farabloc over the stump, it covers the nerve endings and protects them from external magnetic and electric fields, which according to the manufacturer of Farabloc, are the causes of phantom pain.

These fields are said to irritate nerve endings and this is perceived as pain by the brain. Of the 34 patients studied, 21 reported that they experienced greatest pain relief while using Farabloc compared to other treatment methods. Although the clinical significance of this finding may be debatable, Farabloc was found to be comparatively inexpensive and safe to use in the treatment of phantom pain.

References

• http://www.ninds.nih.gov/disorders/chronic_pain/Pain_HTR_brochure.pdf
• http://www.amputee.ca/about-us/amputee-phantom-pain/
• http://www.farabloc.com/pdf/ClinJournReha93.pdf
• http://www.livescience.com/27641-phantom-pain-linked-to-brain-mapping.html

Further Reading

• All Phantom Limb Content
• What is a Phantom Limb

Written by

Susha Cheriyedath

Susha has a Bachelor of Science (B.Sc.) degree in Chemistry and Master of Science (M.Sc) degree in Biochemistry from the University of Calicut, India. She always had a keen interest in medical and health science. As part of her masters degree, she specialized in Biochemistry, with an emphasis on Microbiology, Physiology, Biotechnology, and Nutrition. In her spare time, she loves to cook up a storm in the kitchen with her super-messy baking experiments.