Using plausible illusions to reduce phantom pain

Using plausible illusions to reduce phantom pain

Patients who undergo amputations commonly experience phantom pain, a common side effect. Unfortunately, treatments for this conditions have not been very effective. According to a presentation by Prof. Dr. Herta Flor (Mannheim, D) at the EFIC Congress 2011 in Hamburg, this problem may now be a thing of the past.

(EFIC stands for European Federation of IASP® Chapters. A multidisciplinary professional organization in the field of pain research and medicine.)

The researchers explained that it is now possible to prevent or resolve brain alterations caused by pain. Basically, the patient's brain treats a plausible illusion as if it were real.

Prof. Dr. Herta Flor explained:

"Phantom pain is one of the most common adverse effects of amputation. About 60 percent of patients who have lost limbs suffer from it, but so far there has been hardly any remedy for it. However, latest findings show that within the brain, the remodeling processes that are responsible for phantom pain following an amputation can be prevented or even reversed.

To do so, we use on the one hand the facility of the brain to respond to credible sensory illusions as if they were real, even when the mind knows the truth; on the other hand we use the possibilities of neurofeedback, through which patients can learn to influence certain brain functions directly."

Phantom pain caused by cortical reorganization processes

Phantom pain is a feeling of pain on a limb that is no longer there - it has been amputated. Experts have long been unable to explain how this occurs.

Prof. Flor said:

"The process in imaging techniques has now shown that certain conversion processes take place upon amputation in those parts of the brain cortex that were responsible for the recording of sensory impressions and for the transfer of movement impulses to the now missing limb. To put it briefly, adjacent regions take possession of the no-longer-functional areas for their own tasks, whereby a kind of confusion and even phantom pain results. If we manage to prevent this cortical reorganization, we can also thereby influence the pain."

As part of the European Research Council funded project PHANTOMMIND, investigators are researching the possibilities of such an influence in two different ways.

Getting the brain to think the amputated arm or leg is still there

The human brain is not rational when processing sensation - it considers it as a physical reality.

Prof. Flor says:

"If the brain can be successfully tricked, it will 'believe' that the amputated limb is still there and the pain-inducing conversion processes will fail to take effect. We must therefore help patients to restore their original body image as much as possible and thus provoke the brain into possibly recognizing a prosthesis as the body's real limb."

Researchers are using different methods to investigate this theory:

  • The rubber-hand illusion -a prosthetic hand is placed where the missing hand used to be. Then both hands are stroked. The patient has to keep looking at the prosthetic hand. After a certain amount of practice, patients begin to perceive the replica hand as their own; they experience all the sensations of being touched and stroked whenever the replica hand is being touched. It is important that patients keep looking at their prosthetic hand when this is happening. It appears that the brain automatically files in the missing sensory impression that it is expecting based on prior experience.
  • The mirror therapy - a mirror is placed in such a way that the patient has an optical illusion that their amputated limb is still there. When they move their remaining limb, the optical illusion makes them think the missing limb is the moving one. Within four weeks of this kind of training, the researchers found that reported phantom pain was reduced significantly.
A three-dimensional virtual reality also creates an optical illusion which the scientists are sure will provide effective results. So far, this technique has only been tested on individuals with no limbs amputated.

Prof. Flor, explains

"One arm was hidden by a mirror-like arrangement, while the proband saw through a head-mounted display (data glasses) - in addition to the still visible arm - a lifelike 3-D reconstruction that we could 'move' arbitrarily, not only in synchronization. It turned out that the mere optical illusion of motion triggered the same activities as a real movement in the primary sensorimotor cortex of the part of the brain responsible. The impression of movement in a virtual environment will be perceived therefore as a movement of the body's own limb.

Overall, we found that the effectiveness of an illusion depends on how close it is to reality: how true to nature something such as a rubber hand can be shaped. But in the case of good illusions, we also see a wide range of responses, that is, patients for whom the 'trick' works best and others for whom it does not work at all. The reasons for this are the subject of further research."

Using neurofeedback to consciously control the brain

However, for individuals whose brains are not taken in by optical illusions, investigators have a second, more direct method: neurofeedback. This option was only made possible a short time ago by advances in medical imaging. Neurofeedback allows the direct manipulation of brain activity that can be confirmed in real time by high-resolution functional magnetic resonance images.

Prof. Flor said:

"Healthy probands could successfully learn to willfully regulate downward the activity of bra! in regions through which pain stimuli was triggered, whereby pain perception also decreased. This method seems promising, not only for phantom pain patients, but also for chronic back pain or generalized pain syndromes. With these possibilities for targeted control of the body's own pain perception mechanisms, a whole new world opens up that could soon free us, in many areas, from dependence on analgesic medications, with all their diverse side effects and risk of complications."

How using a mirror can relieve phantom pain (Video Medical And Professional 2018).

Section Issues On Medicine: Medical practice