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New Theory Sheds Light on Phantom Limb Pain

Posted by Bryan Potok, CPO on

Phantom limb pain was first recorded some 400 years ago by French surgeon Ambroise Paré. At that time, he operated on wounded soldiers, many of whom complained of a mysterious pain in amputated limbs. Despite its long history, phantom limb pain remains poorly understood. 

New theory sheds light on phantom limb pain

Recently, the journal Frontiers in Neurology published a paper by Dr. Max Ortiz Catalan, Associate Professor at Chalmers University of Technology and head of the Biomechatronics and Neurorehabilitation Laboratory. Dr. Catalan’s new theory just might be the long-awaited breakthrough.

He called it “stochastic entanglement,” which describes how entangled neural circuitry causes phantom limb pain. 

Stochastic Entanglement 

After an amputation, the neural circuits responsible for processing sensory input and producing motor output in the missing limb loses its role. It becomes prone to entanglement with other neural networks, such as the one responsible for pain perception. 

According to Dr. Catalan, losing a limb “leaves a big chunk of ‘real estate’ in your brain” and in your nervous system. While it has lost its role, the neurons do not go silent. Instead, they might fire at random, which can result in the simultaneous firing of neurons from the sensorimotor and pain perception networks. When they fire together, pain is felt in that part of the body. 

This misfiring and subsequent entangling are explained in “Hebb’s Law” which states, “Neurons that fire together, wire together.”

“Normally, sporadic synchronized firing wouldn’t be a big deal. However, in patients with a missing limb, such an event could stand out when little else is going on at the same time. This can result in a surprising, emotionally charged experience—to feel pain in a part of the body you don’t have. Such a remarkable sensation could reinforce a neural connection, make it stick out, and help establish an undesirable link,” Dr. Catalan said.

Stochastic entanglement also explains why phantom limb pain doesn’t afflict all amputees. This is due to the phenomenon’s stochasticity or randomness, which means that simultaneous firing or linking may not occur in all patients.

Phantom Motor Execution Treatment

Dr. Catalan proceeded to examine how stochastic entanglement can explain the effectiveness of Phantom Motor Execution (PME), a treatment he developed in 2017.

When patients undergo PME, they stimulate and reactivate the dormant areas of their brain through artificial intelligence (AI). During treatment, electrodes are attached to the patient's residual limb to pick up electrical signals intended for the missing limb. These signals are translated into movements for a virtual limb in real time. The patient can see his or her image on a screen with the digitally rendered limb in place of their missing one. 

The treatment works because, according to Dr. Catalan, it uses the idle neural circuitry, which “helps weaken and disconnect the entanglement to the pain network.” Simply put, the treatment invokes an “inverse Hebb’s law”—the more those entangled neurons fire apart, the weaker their connection gets.  

PME can also be used as a preventive measure; it can keep the networks in check and avoid their entanglement in the first place. 

Summary

Stochastic entanglement uncovers what happens in the nervous system post-amputation. It also helps healthcare professionals to understand how and why PME succeeded where other treatments have failed. Clinics around the world are currently testing PME, and it has been able to reduce phantom limb pain in chronic sufferers.
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22 comments


  • I found this article very promising. I intend to ask my doctor where I can try it. My right arm was amputated in 2013 after I suffered a head injury causing me to fall on my right arm not being found for 40 hours. There were several broken bones in my hand and my arm had began to decay.

    My pain varies between my hand and fingers being crushed to my knuckles being on a belt sander. I have some periods of minor pain and then excruciating pain. Pain meds to tend to dull the severe pain. I welcome any solution.
    Doug

    Doug on

  • Really interesting article. I read all the comments trying to find a trick in a more experienced amputee. But I couldn’t. I have tried drugs, all of them and combined too. Mirror therapy, Tens machine, etc. Nothing works for me. My phantom pain is full time and getting worse. I didn’t have pain before the amputations, so that theory doesn’t fit me. The mirror therapy doesn’t works because I can not move my fingers and toes. I feel them clamped and pressed with force. I feel my leg, foot, arm, hand folded backwards in a crazy way. Being hold tightly for something heavy and strong like an anvil or huge vise. But what made me think about this theory as perfect, is that if I pinch my leg in some areas, I feel I’m pinching my hand palm! So, both areas are linked. Something in my nerves and brain is happening for sure. Even opioids didn’t change the intensity of my pain. It’s harder at night because I can not distract my mind. It’s just my phantom pain in the quiet night. With the time is getting worse instead of getting better. I don’t mind having sensations, like itching or even burning, because feels better that the permanent pain. I hate it! I’ll like to try a PME treatment.

    Alexandra on

  • My amputation was way back in 1972. My pain has never gone away. But it did get a little better after I found Dr V. Ramachandran. My hand had been clenched as tight as you can imagine.

    nemia rucker on

  • I live near St. Louis, MO. Is there any place in the St. Louis area that uses this treatment. I would love to try it. Thank you!

    Eileen Boyer on

  • I have been having phantom pain for as long as i can remember my 1st amputation was when i was 18months old they amputated 3quarters of my right foot and toe of my left foot then in november 1990 i had my right leg below the knee amputation all because i had raynulds diss. if you can get a cure for that i would be very happy as sometimes it makes me cry it’s that bad

    Catherine Healy on


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