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 can aid the development of treatment approaches, as well as increase understanding of how the brain reorganises and adapts to new situations.
The Oxford University researchers, along with David Henderson-Slater of the Nuffield Orthopaedic Centre, report their findings in the journal Nature .
‘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,’ says first author Tamar Makin of the Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB) at Oxford University.
"I can feel my fist clenching, my fingernails digging in. I can see the hand isn’t there but the sensation is so realistic. "
Kirsty Mason, who took part in the study
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.
Lynn Ledger, a 48 year old trained therapist and advisor to charities on management training from Nottingham, took part in the study. She had her left arm amputated halfway between the elbow and shoulder in May 2009 after radiotherapy for a rare form of cancer failed to deal with an extensive tumour in her arm. She experiences severe pain as if it was coming from the missing limb.
‘I’ve pretty much tried everything to deal with the pain but nothing has worked,’ Lynn says. ‘There are no drug treatments that work because the condition is not fully understood yet. I can only use various distraction techniques, breathing exercises and mental imagery techniques, to help me manage the pain.
‘It’s very hard to describe the pain to others. I have a nonexistent limb, but I still sense it and feel pain. It’s like: imagine you are wearing a lady’s evening glove that stretches from the fingers up the arm past the elbow. But everywhere the glove covers, it’s as if it’s constantly crushing your arm. There are also shooting pains and intensely painful burning sensations that come and go, but the crushing pain is constant.
‘When I heard about this study I wanted to be involved as it was trying to improve people’s understanding of the condition.’
Kirsty Mason from Bracknell is 22 and about to start a new job as a support worker for people with mental health problems, as well as being an assessor for disabled students for their assisted technology needs. She lost her right arm four years ago just below the elbow after blacking out at a train station and falling on to the rails just ahead of a train coming in. She woke to find a wheel stopped on her arm. Since then she’s learned to write with her left hand and began driving last year. She also took part in the brain imaging study.
‘With me it’s all or nothing,’ Kirsty says of her phantom pain. ‘I get the usual pins and needles and a constant niggling pain that I can shut out by doing other things. But the worst pain is a kind of burning. It’s less frequent but it’s intense: 90-100 on the scale. It sounds silly, but the only thing I can do is stick my hand in a freezer. It numbs it.