Help, hope for amputees with phantom limb pain

Katleho Limakatso recalls the incident clearly. It was August 2012; the physiotherapy student was wrapping up his work in the wards at Wynberg’s Victoria Hospital, almost on his way to catch a bus. Until a man’s sobbing stopped him short.

It was his left foot, he said, the burning pain was unbearable.

Limakatso’s first reaction was to help. But the University of Cape Town (UCT) student wasn’t expecting to find what he did. The patient was an amputee – his left leg had been removed. But he could still feel a stabbing pain in a foot he no longer had.

It was Limakatso’s first encounter with phantom limb pain, a debilitating condition affecting seven out of every 10 amputees in the aftermath of cardiovascular diseases like diabetes, and trauma. The condition is strongly associated with depression, poor sleep patterns and low quality of life.

He stood for a moment wondering, what kind of mysterious pain is this? How is it possible to feel pain in the absence of a limb? What can we do to treat it?

Though still a student, his curiosity was piqued; he needed to find answers.

Pain in the brain

Five years later, with a BSc(Hons) in physiotherapy, PG Diploma and MSc under his belt, Limakatso is now an assistant lecturer and a PhD candidate in the Chronic Pain Management Unit, based in the Department of Anaesthesia and Perioperative Medicine in the Faculty of Health Sciences.

 

“How is it possible to feel pain in the absence of a limb? What can we do to treat it?”

Phantom pain has been stigmatised as a psychological disorder, he said. People with this condition were thought to be mentally ill or faking their pain. However, recent studies using functional magnetic resonance imaging (fMRI) show that the condition is primarily driven by functional and structural changes in the areas of the brain that generate pain.

“For example, when an arm is amputated, you don’t see it or feel it. There’s no external input, which is key to maintaining the integrity of the brain area that controls the arm. As a result, the representation of that arm in the brain starts to shrink – if you don’t use it, you lose it.”

As it shrinks, the representation of neighbouring areas (usually the face) start to take over the area that previously controlled the amputated arm.

“One example to confirm this shifting is that of amputees who report sensations in their missing arm when they touch their cheeks or lips, usually while they are shaving or applying make-up,” Limakatso said.

These changes are associated with the severity of pain – the greater the changes, the greater the pain, he explained. Interestingly, studies also show that these changes can be reversed using simple treatment components, so providing pain relief.

Graded motor imagery programme

In 2018 Limakatso and his supervisor, Associate Professor Romy Parker, completed a randomised control trial investigating the effectiveness of graded motor imagery (GMI) for reducing phantom limb pain in amputees. This three-step intervention activates the areas of the brain that control movements of the amputated limb.

The treatment was initially developed by researchers in Australia. However, the UCT test is the first to be run in Africa and only the second study in the world to be completed. It was recently published in a journal paper.

Their study was conducted in the Victoria, Khayelitsha and Somerset hospitals. The aim of this was to target amputees from different South African cultural groups with varying levels of socio-economic status. In their study, 76% of the patients had undergone amputations because of complications of diabetes (infection and trauma are lesser causes of amputation).

The first phase of GMI focuses on left/right judgements, where patients retrain their ability to judge right from left limbs using an app.

 

“Research has shown that an amputee’s ability to know left from right is very poor, so we retrain them.”

“Research has shown that an amputee’s ability to know left from right is very poor, so we retrain them,” said Limakatso.

During this stage, right and left limbs in various positions are shown on the screen. The patient then identifies the side of the presented limb by pressing either the left or right key on the screen.

At the end of each trial, the app records the accuracy and time taken to complete the trial. A score of 80% or more usually indicates that the targeted area of the brain is still intact.

Steps two and three

The second stage relates to imagined movements, where patients imagine moving their amputated limb into different postures.

“By imagining movement, we are addressing changes in the premotor cortex, an area of the brain that’s responsible for planning movement,” he explained.

The third and last stage is mirror therapy, which is always interesting for patients, said Limakatso. Here the opposite healthy limb is mirrored back at the patient, who sees it as their amputated limb. The visual input from the mirror activates the primary motor cortex, an area of the brain responsible for executing movement.

“This also provides feedback that the movement was successful, thus resolving a visual-motor mismatch that often contributes to pain.”

It’s important to follow this sequence of three steps; these shouldn’t be done in isolation, he said.

The good news is that the treatment works and has been tested in an African population.

“It’s a huge development in pain management,” he said.

“Often pharmacological alternatives don’t work – and medication is expensive – and neither does surgery.”

The next step would be to run a large multicentre trial across South Africa.

Culture and pain

The results of the GMI programme have certainly been very encouraging.

 

“Some patients who had over 5/10 pain severity achieved a total pain relief, 0/10, by the end of the treatment.”

“Some patients who had over 5/10 pain severity achieved a total pain relief, 0/10, by the end of the treatment. These patients were followed up for six months and they had maintained their pain scores.”

What also stood out for Limakatso is the role of culture in determining causes of pain. His Khayelitsha amputee patients often believe that unexplained pain (from a missing limb or appendage) is equated with bewitchment.

“It’s common in our culture; if you can’t explain suffering it’s either a divine punishment or you have been bewitched by an enemy.”

But he is now able to show, via the GMI programme and the results of the study, that the brain is the generator of the pain.

As an indication of just how much of a blueprint the brain provides is that, during the mirroring exercise, patients said they could feel the non-existent limb getting fatigued and heavy and asked to rest.

“It’s real,” said Limakatso.

“And if lactic acid causes muscle fatigue as it has been proposed, why are they feeling tired in a non-existent limb? Or is it all a construct of the brain?”

That, however, is another topic for future research.

“Our main aim with this study has been to create awareness that phantom limb pain is not a psychological condition; it’s real pain.

“We need to inform patients and healthcare practitioners that it can be easily assessed and managed using the graded motor imagery programme. And that this treatment is affordable, accessible and effective.”

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