A new advanced treatment for back pain

By Gabriella Kelly-Davies*
Wednesday, 11 August, 2021

A new advanced treatment for back pain

There is new hope on the horizon for people living with back pain, a leading cause of disability worldwide.

Four million Australians live with back pain — Coffs Harbour banana grower and motor mechanic Jaswir Grewal is one of them.

Jaswir has a decades-long history of crippling back pain caused by his strenuous work, especially the heavy lifting and bending required of a motor mechanic. In the past, pain ruled his life and “took over everything”. He endured three spinal fusion operations for ruptured lumbar discs, but they didn’t relieve his pain. Over time, Jaswir relied on increasing doses of oral opioids and fentanyl patches to get through the day, and he felt as if he was “falling into a dark hole”.

Jaswir eventually travelled to Sydney to the Michael J. Cousins Pain Management and Research Centre at Royal North Shore Hospital. Jaswir was pleased the trailblazing Australian pain medicine pioneer Professor Michael Cousins AO was his doctor. He knew Professor Cousins had pioneered new pain treatments for back pain and was hopeful there might be light at the end of the tunnel for him.

One pain management technique Professor Cousins watched as it evolved was spinal cord stimulation, which first emerged in the 1970s. Pain specialists weren’t sure why spinal cord stimulators reduced back pain in some patients and not others, but they believed the current produced by the device reduced the constant state of heightened reactivity or wind-up in the central nervous system of people with chronic pain.

Professor Cousins said a major problem for researchers and pain specialists, even thirty years after spinal cord stimulators first appeared, was they didn’t know how much stimulation provided pain relief.

“In its early days, spinal cord stimulation was rugged. It was a one-way system. You put in electrical pulses, but you didn’t know what happened to them unless the patient said, ‘Wow, it’s great, or it’s terrible’,” he said.

Another problem was the stimulation often became too strong and could cause intense pain.

“When this happens,” Professor Cousins explained, “most patients turn down the volume of stimulation to prevent painful surges, reducing the amount of pain relief they receive.”

He recalls one patient with a traditional spinal cord stimulator who used to grab a nearby wall or bookshelf to brace himself whenever he coughed. Professor Cousins said he did this because he received a massive overstimulation from a percussion wave travelling through the spinal cord — the spinal cord whipped.

“His experience was like having a little electric shock. In some people, it knocked them off their feet because it hurt so much. The patient ended up turning down the level of stimulation, reducing his pain relief, but preventing the unwanted overstimulation.”

Other patients have reported a thumping sensation associated with their stimulator. “The spinal cord contracts and swells with every heartbeat and this can increase the stimulation to a painful level,” Professor Cousins said. “In some patients, the older-style stimulators effectively turned off with every heartbeat. This meant it switched on, off, on, off, on, off all the time. The pins and needles and the thumping were the motion the spinal cord superimposed on the sensory input.”

Still, thousands of people around the world have benefited from traditional spinal cord stimulation. In a 2011 interview with Australian Doctor, Professor Cousins said in some patients, spinal stimulators make a life-changing improvement. “It can save them from going down the spiral of deterioration in mental and physical functioning that is so frequently seen in chronic pain.”

But, the devices have major limitations and pain specialists don’t know why they help some patients and not others.

The limitations of traditional spinal cord stimulators worried Professor Cousins, so in 2009 he partnered with scientist Dr John Parker to develop a more advanced form of spinal cord stimulation, which the pair hoped would address the problems associated with traditional stimulators. What followed was several years of gruelling early morning studies on sheep in the bowels of a hospital building at Royal North Shore Hospital in Sydney. Once the new stimulator, which had a built-in feedback loop, was ready to trial in patients, Professor Cousins and Dr Parker implanted it in a few patients for a week. It worked and provided essential information to further fine-tune the device.

In 2015, at one of Jaswir Grewal’s appointments at the pain clinic, Professor Cousins told him about the closed-loop stimulator. He explained the risks of surgery and that the new device might not work.

“Would you like to try it?” he asked. “You’d be the first person in the world to have it.”

Jaswir nodded. He accepted the risk because if it helped him his life would be irrevocably changed for the better.

On 13 October 2015, the pain specialist Dr Charles Brooker implanted Jaswir’s device. Professor Cousins assisted with the procedure. Before the surgery, Jaswir said his pain was an eight out of ten, but it was a two out of ten after the surgery.

“As soon as they turned it on, the pain in my back disappeared,” Jaswir said. “It gave me instant mental relief.”

Following Jaswir’s surgery, Professor Cousins supported him while he slowly tapered his opioid use. Now he is thrilled to be entirely drug-free.

“The stimulator has taken over my pain control,” Jaswir said. “It’s doing all the work of the opiates and other pain medications I took. My spinal cord stimulator is the best thing that ever happened to me.”

Dr Charles Brooker said that unlike previous spinal cord stimulators, the closed-loop technology sends signals back from the body to help guide treatment.

“The machine can adjust itself to produce whatever set level the patient wants,” he said. “That’s a big advance because previously, whenever people moved, or their heart was pulsating, various things would make the electrical signal waver up and down quite significantly. They would get shock sensations and not be able to live their lives effectively in many cases.”

“It was a true Eureka moment in pain medicine!” Professor Cousins said. “Conventional implants are blind to what’s happening. They pump out a signal. They can talk, but they can’t listen. In comparison, the closed-loop device enables a two-way conversation. It’s the first device where the stimulus adjusts in response to feedback from the patient’s nervous system, optimising the level of pain relief. So by listening, the device regulates the amount of stimulus to match the level of pain, giving a dose of pain relief tailored to the patient’s needs at the time.”

Repeated studies around the world have revealed the closed-loop stimulators provide significant pain relief in the majority of patients 18 months after implantation. These studies have revealed that overstimulation, shocks and thumping don’t occur with a closed-loop system, enabling patients to maintain a constant stream of stimulation and pain relief, even when they cough.

*Gabriella Kelly-Davies is studying biography writing as a PhD student at Sydney University. During National Pain Week 2021 and the Global Year about Back Pain, Painaustralia launched her biography of Dr Michael Cousins AO — Breaking Through the Pain Barrier: The Extraordinary Life of Dr Michael J. Cousins.

Image credit: ©stock.adobe.com/au/New Africa

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