After a person has had an arm or leg amputated, they may still feel pain in the missing limb as if it is still there. This sensation, known as phantom limb pain, affects 70% of amputees. Now, a researcher has created a new method to treat the condition.
According to Max Ortiz Catalan, of the Chalmers University of Technology in Sweden, phantom limb pain (PLP) can be a serious condition that can severely impact a person's quality of life.
Individuals with PLP can experience various sensations in their missing limb, such as sharp or shooting pains, aches, cramping or burning pains. However, it is unclear why people develop PLP.
There are many methods used to treat the condition. These include acupuncture, hypnosis, various medications and mirror box therapy - using the reflection of the remaining limb in an attempt to move the phantom limb into a comfortable position.
But Catalan says that very few amputees see success from these treatment strategies.
With this in mind, he decided to test an alternative treatment method on an amputee. His subject had been experiencing PLP for 48 years, after having his arm amputated.
Superimposed limbs and augmented reality 'provides pain relief'
Using muscle signals from the patient's arm stump, Catalan was able to trigger a system called "augmented reality."
Explaining the process in detail, Catalan says the muscles in the arm stump send out electrical signals that are sensed by electrodes on the skin. Complex algorithms then translate these electrical signals into arm movements.
On a computer screen, the patient was shown an arm that was superimposed onto his stump. He was able to control the movements of this arm using his own neural command in real time.
After a period of treatment using this method, Catalan says the man now has periods where he is completely free of pain - something that never happened when using already-existing treatment methods.
Explaining why he believes this new method triggers pain relief, Catalan says:
"The motor areas in the brain needed for movement of the amputated arm are reactivated, and the patient obtains visual feedback that tricks the brain into believing there is an arm executing such motor commands. He experiences himself as a whole, with the amputated arm back in place."
He notes that modern treatment methods, such as mirror box therapy, are no use to people who have lost both arms or legs. But this new method could be.
"Our method differs from previous treatment because the control signals are retrieved from the arm stump, and thus the affected arm is in charge," Catalan adds.
"The promotion of motor execution and the vivid sensation of completion provided by augmented reality may be the reason for the patient improvement, while mirror therapy and medicaments did not help previously."
A number of European clinics and three Swedish hospitals are now collaborating as part of a clinical trial for this new treatment method. The trial will involve patients with PLP who have been unresponsive to other treatments for the condition.
Catalan and colleagues have also created a home-based version of this treatment, which patients will be able to use without assistance.
Looking into the future, the researchers hope this method could be applied to other patients in need of mobility rehabilitation, such as individuals with spinal cord injuries or stroke victims.
Medical News Today recently reported on a study detailing how a monkey controlled the limb movements of an "avatar" monkey using its mind - a process the researchers say could be used for the rehabilitation of paralyzed patients.
Written by Honor Whiteman