A new theory may explain phantom limb pain in people with amputations. Dr. Max Ortiz Catalán described how patterns of neuronal activity change when a person no longer has a limb.

The results of this research, which emerged from a previous work that yield an innovative treatment for phantom limb pain based on artificial intelligence and augmented reality, were published in the journal Frontiers in Neurology.

The theory points out that there is a stochastic entanglement at a neuronal level that occurs randomly between the neuro-specificity of pain and the deteriorated sensory-motor circuit, i.e. some neurons responsible for the movement of the amputated extremity are activated at the same time than some neurons responsible for the pain; and a connection between them generates that gives rise to phantom limb pain. Likewise, the text states that these connections can be reversed, reducing the pain.

The Informative Agency of the Mexican National Council for Science and Technology (CONACYT) interviewed Max Ortiz Catalán, PhD biomedical engineering who currently works as associate professor at the Chalmers University, in Sweden. Ortiz Catalán explained that the brain has parts dedicated to the generation of sensations and motor control; and peripheral neuronal networks that are responsible for transmitting those sensations and processing what happens.

Neural reorganization

The circuits associated with the control of a limb are extensive and when a person loses it, all of them abruptly get out of work, but the neurons cannot be completely inactive at any time now.  Sporadically, they will trigger some signal, that is, the networks of the lost limb are activated, and if this happens at the same time the neurons responsible for the sensation of pain are activated, a connection can be generated between them.”

Ortiz Catalán described these connections as a reorganization of the neuronal activity map, which distribution changes after amputation in those patients who experience phantom limb pain, while those who do not have that sensation maintain the original activity.

In a healthy person, the area that is dedicated to the control and sensations of the hand is always the same, while in some patients with amputations a redistribution of the electrical activity is observed in the neighboring areas to the control of the stump or the lips —also close to the control of the hand— because these neural control networks begin to take the resources that the loss of the limb left without utility.”

The researcher pointed out that his theory is based on their findings so far, but more experiments are needed to validate it, or even rule it out, and for this they will expand their work in treating phantom limb pain.

We are already starting an international and controlled clinical trial, in which 10 hospitals from eight countries participate; it is the largest clinical trial that has been done on phantom limb pain worldwide.”

The 70 patients involved are treated with the developed technology and are observed and analyzed through magnetic resonance and electroencephalograms to see if the predictions of the proposed theory are fulfilled in patients with pain in comparison with those that do not suffer pain.

 

Source: Agencia Informativa CONACYT