Neurostimulation offers new hope for chronic pain
The need
According to advocacy group Painaustralia, chronic pain affects more than . The economic and social impacts on those trying to manage their pain and associated issues – including depression, opioid dependency, and early retirement – is profound. Spinal cord stimulation can provide relief from pain related to nerve damage (neuropathic pain), but it is not the solution for all pain-types, including the pain that comes from damage to the skin, muscles, bones, or other tissues (nociceptive pain).
The solution
Associate Professor Mohit Shivdasani is co-leading a team of researchers in the development of an implant that uses a unique form of electrical current to stimulate peripheral nerves near the site where pain originates, aiming to directly block signals associated with pain from reaching the spinal cord and brain. This ‘electro-analgesic therapy’ could show promise for the relief of pain in a range of post-surgical scenarios.
It is not true to say that pain is all in the mind – and yet neural stimulation can play an important role in pain management, blocking the signals that inform the brain’s perceptions of pain, and providing much-needed relief to the millions who suffer from chronic pain.
For a large number of patients, spinal cord stimulation has, for many years, proven an effective technique for the management of pain caused by damage to the nervous system or ‘neuropathic pain’. As neurostimulation specialist Associate Professor Mohit Shivdasani explains, pain signals originating from the periphery travel through the spine to the brain. Spinal cord stimulation involves passing electrical current through the spine to indirectly block those signals, by means of an implanted electrical device. It is, says Mohit, the “gold standard” and is well serviced by a global cohort of commercial manufacturers and clinical specialists.
In search of solutions for the unmet need
Unlike pain caused by damage to the central nervous system, the pain caused by damage to peripheral nerves, skin, muscles, bones or other tissue, typically does not respond to spinal cord stimulation.
Mohit and colleagues from the School of Biomedical Engineering are currently working with members of the at Johns Hopkins University, researchers at the ʹڲƱ School of Biomedical Sciences, and pain interventionists at Royal North Shore Hospital to develop alternative neural stimulation devices capable of providing relief in circumstances where spinal cord stimulation is not effective. In clinical terms, it is an unmet need, and therefore a welcome challenge for the team. It also has profound human dimensions.
If we can suppress the pain during the first two weeks after surgery, then the patient will not have to rely on opioids, and the risk of developing opioid addiction is lower. That's a significant impact
“I've seen videos of people in chronic pain. It's just 24/7 agony,” says Mohit. “You can't focus on anything else because you're just in pain – and you're in pain because the signals are going crazy. You're experiencing pain because your brain is saying, ‘It's painful, it's painful, it's painful’. What we're doing is we're trying to block the signal from reaching the brain in the first place.”
Currently, the team are focussed on the extreme pain experienced by patients after knee replacement surgery, also known as ‘total knee arthroplasty’ (TKA). As Mohit notes, TKA is one of the most painful orthopaedic procedures and typically necessitates a long and, in most cases, excruciatingly painful period of rehabilitation. It is therefore not unusual for opioids to be used as part of the pain management strategy, with the high risk of ongoing opioid dependency.
The technique being explored by the team involves the use of a device, implanted close to the surgery site, that applies a unique form of direct electrical current to local peripheral nerves, blocking the neural signals associated with pain perception.
“If we can suppress pain during the first few weeks after surgery, then the patient will not have to rely on opioids, and the risk of developing opioid addiction is lower. That's a significant impact,” says Mohit.
The team has established proof-of-concept in animal testing and hopes to complete testing in humans within the next few years. As the work progresses, the team will be collaborating with industry partners with a view to the future commercialisation of what they have described as ‘electro-analgesic therapy’.
It is these collaborations, both with interdisciplinary colleagues and with external industry partners, that keep the career engineer so highly motivated.
Says Mohit: “I go to work every day, thinking: ‘What new thing am I going to learn today?’.”