Though often unnoticed, there are more than 2 million people living with limb amputation due trauma, disease, cancer, and malformation across the US. Not only is the process of losing a limb challenging for adjusting to daily actions of living and lifestyle, but 60-80% of amputees also experience Phantom Limb Pain (PLP). Phantom Limb Pain is pain sensation to a limb, organ, or tissue following amputation. It can feel as intense as if the area was never amputated. Patients who experience PLP describe stinging, aching, piercing and burning sensations. For many years, patients were hesitant to mention such pain and it was left untreated. While intial understandings of PLP suggested the pain was psychological or that the lost limb itself was causing the pain, modern studies suggest otherwise. Now it is hypothesized that a combination of peripheral, central neural and psychogenic mechanisms are in place. As a result, the pain may be sourced from changes to the neuron at the amputation stump, upregulation of receptors at the spinal cord, or brain cortical reorganization (where parts of the brain that normally recognize pain are reordered following the amputation). With no cure, a variety of therapies are used to mediate PLP. These include medication to block pain, surgery to remodel the stump or neurons, and other techniques using stimulation, biofeedback and cognitive behavioral therapy. A new innovative technology called the Next-gen Device is creating a prosthetic with an implanted stimulator that connects to the damaged nerve endings to reinstitute connections and ultimately reduce PLP . Though amputation is avoided as much as possible, it is still used as the best solution for certain conditions. As a result, finding new approaches to help prevent harm in such cases and promote equal oppertunities for high quality of life even with disability is critical.
Subedi, B., & Grossberg, G. T. (2011). Phantom limb pain: mechanisms and treatment approaches. Pain research and treatment, 2011, 864605. https://doi.org/10.1155/2011/864605
Kaur, A., & Guan, Y. (2018). Phantom limb pain: A literature review. Chinese journal of traumatology = Zhonghua chuang shang za zhi, 21(6), 366–368. https://doi.org/10.1016/j.cjtee.2018.04.006
Hey Kat, I remember back in my undergrad I took this neuroscience course and we talked about phantom limb pain in conjunction with REM Sleep. During that conversation we discussed how during REM sleep when we have active control of our dreams, symptoms of phantom limb pain magically disappear. I found this old article that discussed that during REM sleep muscle atonia is absent. Which basically means muscle activity is inhibited. What could be done for these PLP's patients is discovery how to induce REM sleep in the person, without them actually being asleep. Studying REM sleep is difficult and not much is really known, but if we could understand why REM sleep is causing muscle atonia, which prevents phantom limb pain from being present, could be a possible future therapeutic treatment or even cures for these amputee's. I wonder if those new neuronal connections that are being made in the amputee are in some way being affected by some random Long Term Potentiation. We discussed a lot in that TBL about LTP and how some neurons circuitry can invade new area's, but what if because of the amputation our bodies are pretending to signal to that missing area because of LTP. The stimulus isn't really there but we still think our arm or leg is there. I don't know just something curious that popped in my head.
ReplyDeleteVetrugno, R., Arnulf, I., & Montagna, P. (2009). Disappearance of "phantom limb" and amputated arm usage during dreaming in REM sleep behaviour disorder. BMJ case reports, 2009, bcr09.2008.0851. https://doi.org/10.1136/bcr.09.2008.0851
This was a very interesting read. Personally, a family friend suffers from this exact situation which makes it even more interesting to me. I've had extensive conversations with him about the sensations of feeling like you still have a leg, but there's nothing there. Even more curiously, the mechanism in which he lost his leg was the result of an IED explosion. Unfortunately, the pain for him can at times be unbearable and he is often reliant on pain killers for comfort.
ReplyDeleteA member of my family has also suffered an amputation injury, in which he cut off his pinky finger doing construction work. Curiously enough, he doesn't experience phantom pain as my family friend does. This has always stumped me, but I never made a correlation until I began doing some research after reading your post. I did some further reading of the first article you referenced, and it says perhaps the mechanism of amputation, and whether or not there was pre-amputation pain, could result in the effects of phantom limb pain. The IED explosion resulted in a "mangled" injury as I'm sure you can imagine, and thus amputation was necessary post-injury. Perhaps the activation of these nerves prior to amputation could be why he suffers such intense pain. On the other hand, my family member's amputation was swift and quick. Perhaps the mechanism of amputation caused the nerve ends to be cauterized which is why he doesn't suffer the phantom pain.
Subedi, B., & Grossberg, G. T. (2011). Phantom limb pain: mechanisms and treatment approaches. Pain research and treatment, 2011, 864605. https://doi.org/10.1155/2011/864605