Phantom Pain Relief: Science’s Latest Breakthroughs

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Many people often deal with long-lasting sensations and pain linked to amputation surgery. There has been a lot of discussion among experts about what actually causes phantom limb pain. Because different studies look at various groups of people, it is harder to pin down the exact reasons.

Researchers took a closer look at earlier phantom limb pain studies to identify the different factors that put individuals at risk of developing pain and sensations post-amputation. Their findings were published in Frontiers in Pain Research in August 2024.

A closer look at the cause and cost of limb loss  

Every year in the U.S., around 185,000 people undergo amputations. The main reasons for these surgeries are vascular disease (which causes 82% of amputations), followed by trauma (16.4%), cancer (0.9%), and congenital issues (0.8%). Furthermore, amputations are more likely to happen to older adults, men, and people of color.

After losing a limb, the total healthcare costs for a patient over their lifetime can be incredibly high, averaging about $509,275. Additionally, 42% of these patients struggle to find work for up to seven years after the surgery, adding to their financial and emotional stress.

Many people with limb loss deal with ongoing changes in how they feel, including various types of pain. Besides the typical post-surgery pain, they might develop phantom limb pain, residual limb pain, and odd sensations like the feeling of the phantom limb retracting towards the residual limb (also known as telescoping phenomena).  

A study from 2020 found that as many as 82% of people who had an amputation experienced phantom limb pain within the first year. The chance of having this type of pain or sensation over a lifetime is also high, estimated to be between 76% and 87%. Additionally, about 25% of people with limb loss report experiencing telescoping.

Meanwhile, another research suggests that phantom limb pain might be lower, with estimates of around 64%.

Risk factors of phantom pain  

In the August 2024 review, researchers looked into the causes of phantom limb pain and grouped the risk factors into three stages: before surgery (pre-operative), during surgery (peri-operative), and after surgery (post-operative). The researchers also found that the important factors that contribute to this type of pain include age, ongoing health issues, and the surgical methods used.

Before Surgery (Pre-operative)  

The researchers split the risk factors before surgery into two categories: those that cannot be changed (non-modifiable) and those that can be changed (modifiable).

Non-modifiable factors include things like age, gender, and race. On the other hand, modifiable factors are aspects that patients can influence, such as:

• Lack of support from family or community

• The severity of chronic health problems, like diabetes

• Levels of pain experienced before the procedure

• Not receiving counseling before the surgery

• Having no history of congenital limb loss

• Previous mental health issues, such as anxiety or depression and a tendency to see things negatively (catastrophizing)

Over the past eight years, research has highlighted two key pre-operative risk factors for phantom limb pain. The first is that older patients tend to have a higher risk. The second is that patients who haven’t responded well to past pain treatments may have a lower ability to adapt after an amputation.

During Surgery (Peri-operative)  

The researchers also found that how the surgery is performed can influence phantom limb pain. Research shows that using advanced surgical techniques might help reduce the chances of developing this type of pain.

One traditional method often used during amputations is called traction neurectomy. In this procedure, the surgeon cuts a nerve while pulling it, allowing it to pull back further than the amputation site. This can sometimes lead to a painful nerve growth called a neuroma.

Although only a small percentage (4.2%) of chronic phantom limb pain is linked to these neuromas, studies from 2018 and 2022 suggest that newer surgical methods, which reconnect the severed nerve to a healthier nerve or preserve the nerve structure better, can lower the risk of both neuromas and phantom limb pain.

The type of surgery can influence phantom limb pain. Research shows that using advanced surgical techniques, like TMR and RPNI, might help reduce the chances of developing phantom limb pain.

One innovative technique is known as Targeted Muscle Reinnervation (TMR). In TMR, the surgeon reroutes a cut nerve to a healthy nearby muscle. This allows the muscle to pick up signals from the nerve, which can then be used to control prosthetic limbs.

Another method is called Regenerative Peripheral Nerve Interface (RPNI), where a piece of muscle from the amputated limb is placed around the cut nerve and positioned away from the surgical area.

Studies have shown that TMR and RPNI can significantly lower the chances of developing phantom limb pain to between 0% and 56%, compared to higher rates of 64% to 91% in traditional methods. Although the researchers noted that more extensive long-term studies are needed to confirm these findings, these early results emphasize the importance of discussing surgical options that can help minimize phantom limb pain.

After Surgery (Post-operative)  

After amputation surgery, the researchers found that the main risk factors for phantom limb pain include the level of pain felt after surgery, the length of the residual limb, the strength of the sensations felt, and the presence of telescoping. Phantom limb pain can sometimes start soon after the amputation, sometimes as quickly as seven days later.

Of the post-amputation patients reviewed, the researchers found that about 85% of those who undergo an amputation will experience phantom limb pain. Interestingly, while immediate post-surgery pain has some connection to phantom limb pain, the pain that occurs a bit later (sub-acute pain) is a stronger indicator of whether someone will continue to experience pain 12 months after the amputation.

The type of amputation also seems to be a risk factor. The researchers found that people with lower limb loss or limb loss in areas closer to the center of the body (proximal) are more likely to suffer from phantom limb pain. It’s not entirely clear why lower limb amputations lead to more pain than those of the upper limbs, but it’s possible that changes in how the brain and nervous system adapt (maladaptive plasticity) play a role. The central pattern generators, a group of neurons in the spinal cord, are important for controlling movement. Changes in how these systems work may contribute to phantom pain.

But some recent studies have suggested ways to ease phantom limb pain. A 2018 study found that using a prosthetic leg equipped with a biofeedback system could help reduce both the severity and frequency of the pain. Additionally, a 2020 study suggested that having the sensation of moving the phantom limb might protect against experiencing pain.

The bottom line  

Although phantom limb pain continues to be a significant challenge for many individuals with limb loss, researchers are starting to get a clearer picture of the risk factors involved and how modifiable factors can be avoided or minimized. The researchers in this review recommend continued research for a more nuanced understanding of this phenomenon.

However, with advances in surgical techniques such as TMR and RPNI, there is hope for reduced incidence of phantom limb pain in the future.

If you or someone you know is currently experiencing phantom limb pain, it’s crucial to consult with healthcare professionals who specialize in pain management or rehabilitation. They can provide personalized treatment plans, which may include medications, physical therapy, or alternative therapies like mirror therapy or acupuncture.

Additionally, engaging in support groups can offer emotional support and shared experiences that may help alleviate some of the mental health challenges associated with limb loss. Lastly, staying informed about new research developments can empower you to discuss potential options with your doctor.