Amputee phantom pain linked to brain retaining picture of missing limb

Changes in the brain following amputation have been linked to pain arising from the missing limb, called 'phantom pain', in an Oxford University brain imaging study.

Arm amputees experiencing the most phantom limb pain were found to maintain stronger representation of the missing hand in the brain – to the point where it was indistinguishable from people with both hands.

The researchers hope their identification of brain responses correlated with the level of phantom pain to aid the development of treatment approaches, as well as increase understanding of how the brain reorganises and adapts to new situations.

Oxford University researchers, along with Dr David Henderson-Slater of the Nuffield Orthopaedic Centre, reported their findings in the journal Nature Communications. They were funded by the Royal Society, Marie Curie Actions, the Wellcome Trust, National Institute for Health Research (NIHR) Oxford Biomedical Research Centre, and the Medical Research Council.

"Almost all people who have lost a limb have some sensation that it is still there, and it's thought that around 80 per cent of amputees experience some level of pain associated with the missing limb. For some the pain is so great it is hugely debilitating," says first author Dr Tamar Makin of the Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) at Oxford University.

Treatments for phantom limb pain tend to be limited to standard drugs for pain relief. The origin of the pain is not well understood. There may be many factors that lead to the pain, including injured nerve endings where the limb was lost and changes in the brain areas connected with the missing limb.