Phantom limb pain is the feeling of pain from a body part that has been removed, most commonly an arm or leg. While once thought to be psychological, modern imaging shows these sensations are real and originate in the spinal cord and brain. Functional MRI scans reveal activity in brain regions once connected to the amputated limb, confirming the experience is a physiological event.
The Sensation of a Missing Limb
The sensations of a phantom limb vary widely. Individuals may report sharp, stabbing, or shooting pains, while others describe burning, cramping, or throbbing. It can also feel as though the missing limb is held in an uncomfortable position. The frequency of these episodes is often intermittent and can be triggered by stress, fatigue, or changes in temperature.
It is helpful to distinguish phantom limb pain from two other experiences. One is phantom limb sensation, the non-painful feeling that the limb is still attached to the body. This can include feelings of touch, pressure, or itching where the limb used to be, and a person might momentarily forget the limb is gone.
Another condition is residual limb pain, or stump pain, which is located in the remaining part of the limb. Unlike phantom pain, this discomfort has a direct physical cause, such as:
- A poorly fitting prosthesis
- Skin infections
- Nerve damage
- Poor blood flow
- Bruising
An individual can experience both residual and phantom limb pain at the same time.
Neurological Origins
Phantom limb pain is understood to stem from changes in the peripheral and central nervous systems following an amputation. The brain contains a sensory map of the entire body, and when a limb is removed, the corresponding area no longer receives sensory input. This lack of signals can trigger the brain to send a pain message that something is wrong.
This process leads to brain reorganization, or neuroplasticity. The section of the brain connected to the amputated limb becomes inactive, so adjacent areas of the brain’s map, like those for the face or shoulder, can expand into this unused territory. When these neighboring parts of the body are stimulated, the brain can misinterpret the signals as sensations from the missing limb. The extent of this reorganization has been correlated with the amount of pain a person feels.
At the amputation site, severed peripheral nerves can also contribute to phantom pain. These nerve endings can become damaged and overly sensitive, sometimes forming disorganized masses of nerve tissue called neuromas. These neuromas can generate spontaneous electrical signals that travel up the spinal cord to the brain, which interprets them as pain from the missing limb.
Managing Phantom Pain
Managing phantom limb pain often involves a combination of strategies to alter nerve signals and brain perception. One widely used non-invasive method is Mirror Therapy. This involves placing a mirror to reflect the existing limb, creating a visual illusion that the amputated limb is intact. By moving the intact limb and watching its reflection, the person can “trick” their brain into thinking it is controlling the missing limb, which can help alleviate painful sensations.
Other non-invasive options focus on disrupting pain signals. Transcutaneous Electrical Nerve Stimulation (TENS) uses a device to deliver a mild electrical current to the skin near the area of pain, which can interfere with pain messages to the brain. Massaging the residual limb can also help by desensitizing the area and improving circulation.
Medication is another management option, though traditional painkillers are often not the most effective solution. Treatments frequently involve medications that target nerve pain specifically, like certain antidepressants and anticonvulsants. These work by calming the hyperexcitable nerve signals that contribute to phantom pain. For severe and persistent cases that do not respond to other treatments, more invasive procedures like spinal cord or deep brain stimulation may be considered, which use implanted devices to modulate pain signals.