Phantom limb: feeling a limb that was lost


Have you ever heard that people with amputated limbs can feel pain or itching in the limb they lost?

This is called phantom limb syndrome. Here we review what science says about its possible causes.

It is estimated that 90% of people who have had a limb amputated can feel as if it is still there, including:

  • Pain.
  • Hot or cold.
  • Numbness.
  • Tingle.
  • Mobility of the fingers that are no longer there.
  • Punctures.

There are ways to relieve or reduce these discomforts:

  • Rub or exercise the remaining part of the limb to keep it warm.
  • Tricking the brain through distractions, hobbies, relaxation techniques, or exercises.
  • Use non-invasive therapies, such as acupuncture.

The exact cause of this syndrome is currently unknown, although an imaging study from two research centers in Rio de Janeiro, Brazil, identified changes in how certain areas of the brain communicate as a result of amputation.

These alterations occur in the regions of the brain that control movement and process touch.

  • New material to develop sensitivity in prosthetics

While there are many studies on phantom limb pain, the lead author of this paper, Ivanei E. Bramati, a medical physicist at the D’Or Institute for Research and Education, said his research found there is an imbalance in brain function of patients who report phantom sensations, even though they do not feel pain.

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Their findings were published in Scientific Reports.

The secret of sensation

Brain plasticity is the brain’s ability to adapt its structure and function to changing situations.

There is a “general acceptance” that the adult brain can change in response to different factors:

  • Learning.
  • Stress.
  • drugs.
  • hormones
  • stimulation.
  • Aging.

In the new paper, the authors refer to studies that have linked the phantom limb to a failure of brain plasticity. However, they also point out that more recent research has challenged this idea.

These contradictions suggest that the phantom limb may not be due to one cause, but to many.

To delve into this phenomenon, the researchers analyzed the brain connection in 9 individuals with lower-limb amputations experiencing phantom sensations without pain, and 9 individuals without amputations.

Magnetic resonance imaging revealed the following:

  • Touching the stump of a limb caused the brain to overreact.
  • Amputation appears to weaken the structure that connects and allows communication between the left and right hemispheres of the brain.
  • The area that controls movement and touch of a limb is located on the side of the brain that is opposite the limb itself.
  • From these findings, the authors concluded that amputation of a limb can cause a disorder in the organization of the brain’s connections, causing a variety of sensations.

    Options to treat it

    If the pain or discomfort caused by phantom limb syndrome becomes persistent, a doctor may prescribe some medications for relief:

    • Pain relievers or opiates.
    • Anticonvulsants.
    • Antidepressants.
    • Baclofen (muscle relaxant).
    • Chlorpromazine (used to treat schizophrenia).
    • Clonidine (useful against pain generated in the brain).
    • There is also research showing that stimulation of the nerves or brain regions involved in pain may help some patients. The most common options to achieve this are:

      • spinal cord stimulation: An electrode is placed and a small electrical current is applied to the spinal cord to relieve pain.
      • transcranial magnetic stimulation: is a procedure that involves a strong magnetic impulse through the scalp to the brain. Although it is believed that this option would only provide temporary relief.
      • transcutaneous electrical nerve stimulation: A small electrical current is sent through the skin to points on the nerve pathway.
      • Sources consulted: US National Library of Medicine, Mayo Clinic, National Institute of Mental Health.

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