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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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23 comments


  • This is very interesting to me.Heart attack 11/30/14, stent 12/1/14 Left BKA 12/24/14, right partial foot amputation 2/7/15; some additional cardiac irregularity 2/8/15-2/13/15. Back at rehab. Right foot wasted no time in permitting Lbka to experience some of its shock and discomfort. At this time it bites the bullet and deals with its autonomy, by far the louder of the two . . . .

    Darrel Smith on

  • The perfect picture is what grabbed my attention first. It depicted exactly how I feel! My left leg was amputated AK 13 months ago. I have both phantom pain and phantom sensations. In Rehab, I tried mirror therapy which was a disaster for me. I am interested in the new PME treatment. How do I find the right Dr? A neurologist? I live in Seattle. I do receive your newsletter. I’ve learned a lot – Than you!! Jill

    Jill on

  • I do suffer incredible phantom pain which can last a couple of days. My brain feels like it is being hit by lightning and the phantom pain is severe. What is the success rate of this treatment and how many sessions are needed. I live in MD. Is there anyone in MD I could talk to.

    Dorothy Ortiz on

  • I’ve had famtom pain for approximately 25years
    It has recently gotten worst. My Doctors usually treat it with pain medication. This article is very interesting.

    Faye on

  • Since I lost sleep just last night with “phantom pain” I find this article most useful. I have not only pain, but my leg actually “jumps” up and down, as when the Dr. used to take the rubber hammer and get a response like a spasm, or the leg jumping up in a reflex manner. Does anyone else experience this? This causes lack of sleep, that’s for sure!

    Eleanore Rainey on


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