Among arm amputees who experienced phantom pain, patients who experienced the most pain maintained a stronger representation of the missing hand in the brain, according to recent study results published in Nature Communications.
“Almost all people who have lost a limb have some sensation that it is still there, and it’s thought that around 80% of amputees experience some level of pain associated with the missing limb. For some the pain is so great it is hugely debilitating,” Tamar Makin, PhD, of the Centre for Functional Magnetic Resonance Imaging of the Brain at Oxford University, stated in a news release.
Using MRI imaging to study how phantom limb pain felt by individuals who have had an arm amputated is related to changes in the brain, Makin and colleagues compared MRI data for 18 amputees with differing levels of phantom pain with a control group of 22 adults with two intact limbs. To see how the missing hand is represented in the brain, participants were asked to move the fingers of the phantom limb while in the MRI scanner.
Overall, the researchers found that the brains of the amputees maintained its representation of the missing hand, and those feeling the greatest phantom pain retained the strongest representation of the missing hand. Compared with the non-amputees, amputees with stronger phantom limb pain had less structural degeneration in the area of the brain representing the missing limb following its loss, according to study results. However, there was evidence that connections to other parts of the brain were disrupted.
“Most people experience “phantom” sensations in a missing limb after amputation. This disconnect between the physical world and what they are experiencing appears to be linked to a functional detachment in the brain,” Makin stated. “There seem to be reduced connections between the missing limb part of the brain and the rest of the cortex that’s involved in movement. Our results may encourage rehabilitation approaches that aim to re-couple the representations of the phantom hand with the external sensory environment.”