We may often feel pain around our bodies that triggered by various types of stimulation, such as heat, cold, pressure, skin damage, illness, injury – even heartbreaks have been recognized as pain that can be felt physically. But have you ever thought about pain felt in a body part that no longer exists? This kind of pain is known as phantom limb pain, which is often experienced by individuals who have undergone removal of a body part (i.e. amputation).
What does Phantom Limb Pain feel like?
Everyone experiences pain differently. However, many patients describe phantom limb pain as:
- Pins and needles
The striking thing about these sensations? Patients identify them in the missing body part. For example, someone may experience burning pain in their ankle although their entire leg has been removed. Such symptoms can be experiences as early as one week after amputation, but may also occur delayed in weeks or months later. The pain may be continuous or come and go. Fortunately, symptoms are likely to decrease and improve as time progresses.
The term ‘phantom’ may lead people to think that the pain experienced is imaginary. However, neurological studies have identified neural activation in the brain’s pain centres during the experience of phantom limb pain: the pain is real.
Why does Phantom Limb Pain occur?
The exact causes of phantom limb pain remain unclear, but several theories exist.
Cortical Reorganization and Neuroplasticity
The brain undergoes neural reorganization to adapt to the physical changes. Such so-called neuroplasticity is crucial for humans, as it allows us to learn to function in new circumstances.
Take for example a leg amputation: There are areas in the brain that process information about sensory stimulation (somatosensory cortex) and movement (motor cortex) of the leg. These areas no longer receive input from the corresponding limb after it has been removed. As a result, adjacent areas that correspond to other body parts begin to dominate and extend into the leg area. Thus, this area now receives sensory and motor signals from other body parts. Individuals may experience this reorganization as touch, movement, and pain occurring in the leg that they no longer have.
This theory proposes that individuals have specific memories regarding their limb positions, even after amputation. These memories include pain sensations associated with the limb which are often experienced during injury or illness leading up to the amputation. Research hypothesizes that these pain memories are embedded within the individual’s subconscious, contributing to phantom limb pain.
Peripheral Nervous System Theory
This theory suggests that phantom limb pain is a result of nerve endings clump that together at the stump of the limb after an amputation. The nerve clusters, known as neuromas, exhibit abnormal activities that the brain may interpret as pain.
How can Phantom Limb Pain be eased?
The most common medication used to treat phantom limb pain includes opioids, anticonvulsants, ketamine, and nonsteroidal anti-inflammatory drugs. Medication effectiveness differs for every patient. For example, morphine has shown some success in decreasing phantom limb pain in some clinical trials, however, for war-wounded service members high doses of methadone do not show any signs of pain relief. This highlights the important contributions of context of injury and type of trauma to phantom limb pain.
In mirror therapy, a mirror is placed on the side of the amputated limb while facing the remaining limb. The individual is then instructed to move the healthy limb while observing the movement in the mirror, so it appears that they have two moving limbs. This therapy has been found successful not only in reducing phantom limb pain, but also allowing individuals to decrease their medication intake. The effects of mirror therapy may be a result of addressing neural reorganization issues by allowing visual feedback to brain areas previously responsible for processing signals relating to the limb.
In addition to medication, the following treatments can be helpful in relieving phantom limb pain:
- Acupuncture – stimulates nervous system and relieves pain
- Massage – increases circulation and stimulates muscles
- Transcutaneous electrical nerve stimulation (TENS) – sends electrical currents to stimulate nerves at the stump and relieve pain
post by Besty Yeong & Esslin Terrighena