A new theory for phantom limb pain points the way to better treatment
Researchers have worked on a new hunch for the beginning of the mysterious condition, ‘phantom limb pain’. The unproven principle bases upon previous analysis on a revolutionary treatment for the condition, that uses machine learning and augmented reality.
Dr Ortiz C. from Sweden, has developed a new proposition for the genesis of the mysterious condition, ‘phantom limb pain’. Published in the medical journal, his hypothesis bases upon his previous research on a revolutionary treatment for the condition, that uses machine learning and augmented reality.
Phantom limb pain is a vaguely researched phenomenon, in which people who have lost a limb can feel severe pain, seemingly located in that missing part of the body. The condition can be seriously exhausting and can reduce the sufferer’s quality of life. But modern ideas on its origins cannot explain clinical findings, nor support a comprehensive framework for its treatment.
Now, doctor Ortiz C has published a paper that explains a better new theory — one that he terms ‘stochastic entanglement’.
He proposes that after an amputation, neural circuitry in the brain related to the missing limb loses its role and becomes susceptible to entanglement with other neural networks — in this case, the neural network responsible for pain perception.
“Imagine you lose your hand. That leaves a big chunk of ‘real estate’ or wires in your brain, and in your nervous system as a whole, without a job. The wires are dangling in the neural circuitry. It stops processing any sensory input, it stops producing any motor output to move the hand. It goes idle — but not silent, the wires are containing charged particles,” explains professor Ortiz.
Neurons are never completely silent. When not processing a particular job, they might fire at random. This may result in coincidental firing of neurons in that part of the sensory motor network, at the same time as from the network of pain perception. When they fire together, that will create the experience of pain in that part of the body.
“Normally, sporadic synchronized firing wouldn’t be a big deal, because it’s just part of the background noise, and it won’t stand out,” continues the professor. “But in patients with a missing limb, such event could stand out when little else is going on at the same time. This can result in a unexpected, emotionally charged experience — to feel pain in a part of the body you don’t have. Such a noticeable sensation could strengthen a neural connection, make it stand out, and help establish an unwanted link.”
Through a principle known as ‘Hebb’s Law’ — ‘neurons that fire together, wire together’ — neurons in the sensorimotor and pain perception networks become entangled, resulting in phantom limb pain. The new theory also explains why not all amputees suffer from the condition- the randomness, or stochasticity, means that simultaneous firing may not occur, and become linked, in all patients.
In the article, the professor goes on to examine how this theory can explain the effectiveness of Phantom Motor Execution (PME), the novel treatment method he previously developed. During PME treatment, electrodes attached to the patient’s residual limb pick up electrical signals intended for the missing limb, which are then translated through AI algorithms, into movements of a virtual limb in real time. The patients see themselves on a screen, with a digitally rendered limb in place of their missing one, and can then control it just as if it were their own biological limb . This allows the patient to stimulate and reactivate those dormant areas of the brain.
“The patients can start reusing those areas of brain that had gone idle. Making use of that circuitry helps to weaken and disconnect the entanglement to the pain network. It’s a kind of ‘inverse Hebb’s law’ — the more those neurons fire apart, the weaker their connection. Or, it can be used preventatively, to protect against the formation of those links in the first place,” he says.
The PME treatment method has been previously shown to help patients for whom other therapies have failed. Understanding exactly how and why it can help is crucial to ensuring it is administered correctly and in the most effective manner. Ortiz’s new theory could help reveal some of the mysteries surrounding phantom limb pain, and offer relief for some of the most affected sufferers.