NP: Phantom Pain

PsychologyCode Series – Article 4 [ Originally Written on July 30, 2013 ]
Neuroplasticity: Phantom Pain

Today we are going to talk about something ghostly – The Phantom. As we talked about earlier, what we experience (our perception) is a complex product built from memories of the past, information from the present, and expectations about the future. Our brain does its best to build an experience of reality from all of these sources. However, when the brain loses input from certain organs it ends up needing to rely on other sources, and when it does this it is more likely that it will make mistakes. While normally the brain can learn from its mistakes and correct itself, without some sort of feedback to recognize the errors its self-correction process can become very challenging. In fact, sometimes these mistakes result in a perception false perception, such as a ghost or phantom.

During the war, many soldiers underwent amputations in order to prevent infections from certain wartime injuries. In a lot of cases, the soldiers lost appendage was not the worst part of an amputation. Many times they would wake up one morning only to realize they could feel their arm, for instance. They would even feel their ‘phantom’ hand reach out to open doors, or to attempt to catch them when they fell.  The worst part of this was that many times their phantom would return with all the pain it experiences during the moment of the incident. It would seem that this persistence of memory was being projected from the brain into an all too real experience. Some patients suffering from this condition also experienced their phantom clenching its phantom fingernails into the phantom hand, and others who did not experience intense pain still experienced their phantom as a paralyzed dead weight. With no sensory feedback to tell the brain that the hand no longer was there it simply stewed in these perceptions. These symptoms were first reported before the acceptance of neuroplasticity, and because of this doctors did not have any solutions to offer. In fact, doctors at the time were not even likely to appreciate the realness of this perceived pain. Sure the pain may have been psychological, but it still felt as real as any other type of pain.

A doctor by the name of Vilayanur S. Ramachandran had theorized about the connection between phantom limbs and neuroplasticity. He believed that the phantom experience was a result of the lack of sensory feedback. With no information relating to the ‘status’ of the hand, the brain had to make sense or fill in the missing information in another way, such as projecting memories or interpreting the lack of sensory information as paralysis. Vilayanur believed these phenomena were occurring because the brain was not receiving information any sensory information to tell it otherwise. He thought that if this illusion seemed so real then maybe another illusion could be used to invalidate this false phantom perception. He constructed a simple device called a mirror box which was designed to trick the brain into thinking it was receiving real sensory information from the missing limb. Below is a very rough sketch of the mirror box. The mirror would reflect the image of the functional hand in order to produce an illusion that their amputated hand had returned.

A box with a mirror was used to reflect the image of a patient’s function hand into the space where the patient’s phantom was perceived.

When patients used this mirror box miraculously they perceived their phantom hand as if it had come back to life. The perceptions of clenching, pain, and the paralyzed dead weight feeling all subsided. What was even more remarkable is that after continual treatment with the mirror box many patients would awake one morning and find that their phantom had vanished. While the mirror box technique was not effective for every patient the results were still very astonishing. Modern techniques have also been developed using a virtual reality device in order to produce the illusion of sensory feedback from the missing limb.

The brain is pretty good at figuring things out, however, when it gets stuck sometimes all it needs is a simple nudge in the right direction to help it along.

More Information:

The Mirror Cure for Phantom Pain
Phantom-Limb Pain Eased with Virtual Reality
Mirror Therapy for Phantom Limb Pain