Proprioception: Balance and Phantom Limbs
24 Phantom Limbs
Learning Objectives
Know what a phantom limb is.
Be able to describe three possible reasons that people experience phantom limbs or phantom pain.
Be able to describe how mirror boxes are used to treat phantom limb pain.
Know what congenital limb deficiency is.
Be able to explain why individuals with congenital limb deficiency experience phantom limb pain.
In this section, the focus of learning is to understand more about phantom limbs. Very few people have personal experience with phantom limbs because it requires for a limb to be absent. There are numerous causes of this ranging from car accidents where someone loses a limb to a birth defect where a child is born with only one arm or leg. Now, I think everyone is wondering, what is a phantom limb? A phantom limb is the sensation of feeling various things in a limb that is not there (e.g. a tingling sensation in an area where a limb no longer exists).
There are multiple complications that could be caused in experiencing sensations in limbs that are no longer existent. One of the main complications is phantom pain, which is a painful sensation in phantom limbs. There are three different ways that an individual could experience phantom pain. The first is called Neuroma, which is a physical source of pain caused by scarring on nerve endings. Sometimes, neuroma can be treated by surgery to remove the growth/tumor on the nerve, although the neuroma might re-grow after surgery, so the treatment is not always effective. The treatments for Cortical causes of phantom pain are less obvious. The first Cortical cause is negative sensory deprivation. For example, if the last thing a person felt on their arm before it got amputated was pain, the person’s brain could be stuck in that state. The second Cortical cause is sensory reorganization, and the issue here is that nerves from an amputated limb could grow back and infiltrate a different area of the body causing pain.
There is new technology being used, though, that can help people struggling from phantom pain with Cortical causes called mirror boxes. Mirror boxes are treatments that rewire the brain to portray a lack of sensory responses as not being painful. It allows a person’s brain to not think of an absence of sensory responses as pain and it allows the person to be at ease rather than feeling pain.
Moreover, you may be wondering how an individual could experience pain in a missing limb if they have never had one. Congenital limb deficiency is when an individual is born without a limb, failing to fully develop the limb in the uterus. There have been reports of these individuals having phantom pain in a limb they never had. The working theory for this is that the human body has a neural network that underlies the body schema (an organism’s internal model of it’s body and position of limbs) that develops regardless of whether or not it had received sensory input from a particular limb. Evidence e