How can a paralyzed feel pain?

Answer

The same phenomenon occurs in people who have lost a body part due to amputation, for example an arm, hand or leg. They can feel, often severe, pain from the body areas that are no longer present. This is generally referred to as phantom limb pain. In fact, scientists cannot yet fully explain this phenomenon. There are several possible explanations, which require first understanding how pain perception normally works.

The perception of pain in the body occurs on three levels: first, neurons (nerve cells) carry signals from the body to the spinal cord, then the spinal cord carries those signals to a part of the brain called the thalamus, and finally the signals are passed from the thalamus to another part of the brain, namely the sensory cerebral cortex where the information is processed into pain sensation.

After damage to the spinal cord, a number of things can go wrong, it is believed:

1. the damaged spinal cord can send misinformation to the thalamus
2. after the loss of the normal information the thalamus receives, it can send wrong information to the cerebral cortex
3. the cerebral cortex can undergo a “remodeling” after the accident, which sometimes causes it to work incorrectly, e.g. misinterpreting stimuli from non-paralyzed areas as pain stimuli emanating from the paralyzed areas.

Some scientists also believe that the brain has a kind of 3D impression, and that it also retains the entire body after an accident. If they no longer receive signals from certain parts of that body after an accident or amputation, this could disrupt their functioning. This could possibly partly explain the phantom pain in addition to the above possibilities.