Where next for EMG within the patient care pathway?
Authors: Amedeo Leproni and Rob Morgan
Electromyography (EMG) is a field which has been researched and applied in the world of healthcare for decades, having reached technological maturity for diagnostic use. Great strides have been made in developing hardware and software system components making this technology highly useful and applicable in diagnosis, assistive technology, and robotic rehabilitation.
The continuum of care is an approach to complete patient recovery where treatment continues after leaving the hospital or the clinic. EMG may prove a key component in bringing the continuum of care out of clinical environments and into the home by providing medical professionals with remote real-time patient information for use in telemedicine.
What is Electromyography (EMG) and its core features?
EMG is the measurement of biopotential signals in skeletal muscles. The nervous system enacts the decision to contract a certain muscle through a nerve impulse, starting in the brain, passing through the nerves and finally reaching the muscle through innervation. Innervation disseminates an action potential throughout the muscle whereby all the muscle fibres contract. EMG records this action potential. Due to the physical context in which EMG is recorded, the recorded signals contain overwhelming interference and noise. However, decades of research and development have produced clean and amplified biopotential signals that provide very useful insights on the state of muscle contraction.
Some key features of EMG recording are outlined:
Muscular contractions can be voluntary if the nervous system is at least partially working, but as an effect of various health conditions, may become involuntary. This distinction is important because greater levels of assistive care can be provided when patients have some motor control, whereas a narrower range of solutions can be provided through EMG when contractions are involuntary.
EMG implementation types
Within the context of healthcare, there are a few avenues in which EMG can make impactful contributions. These are namely diagnosis, assistive technology, and rehabilitation technology.
EMG is a very useful tool to help medical practitioners diagnose a range of disorders affecting muscles, innervation, peripheral nerves, motor neurons, or nerve roots. Some examples of these conditions are muscle dystrophy, carpal tunnel syndrome, multiple sclerosis or a herniated disk. It is possible to have EMG examinations in many hospitals and clinics. Diagnostic EMG primarily involves needle electrodes rather than surface electrodes and is typically carried out together with a nerve conduction study (NCS).
- Assistive technology
Within the world of assistive technology, upper limb prosthetics is an area of particular focus. These are not yet ubiquitous due to their many shortcomings – with high cost at the forefront of the list. However, with the advent of 3D printing, some manufacturers have begun to tackle the mission of affordable, functional prosthetics. A pioneer in this sector, for example, is Open Bionics, with custom fitted bionic arms costing approximately £10,000. These use EMG sensors to differentiate sets of two hand gestures, placing one on the anterior and one on the posterior residual forearm muscles. The system is very robust, though the restricted scope of classification only enables the detection of two hand gestures at a time. This is a humble beginning in the quest to replicate the biological dexterity of the human hand. Open Bionics have opened the door to both technological advancements of affordable upper limb prosthesis and social acceptability of prosthetics, achieving the latter through partnerships with Disney, Marvel and Lucasfilm to bring beloved characters onto their children’s prosthetic arm covers. In the next decade, academic findings on the optimisation of hand gesture recognition using EMG will consolidate and trickle into industry. We can expect to see active prostheses become more sophisticated in their ability to differentiate multiple nuanced hand gestures, creating better performing and more intuitive devices for users.
- Rehabilitation robotics
Rehabilitation robotics are most intuitive when paired with EMG sensors in applications such as robotic aids and even exoskeletons, as well as giving physiotherapists a way of monitoring muscular progress. The company Hocoma, for example, has clinics containing state of the art rehabilitation machines. EMG is implemented within these as a control signal in human-computer interface to inform the robotic system on when and how to assist patient movements. In later stages of rehabilitation, it can be used to inform the system on how to resist user movements with the aim of building strength. Another example is Cyberdyne’s HAL exoskeleton, where EMG is used to intuitively control the patient’s walking direction and pace. For both companies, the extremely high costs of these robotics systems confine them to professional clinics to be used by many patients rather than privately owned. These robotic systems can be expected to evolve slowly as rigorous improvements in cost, weight, control, and safety are required before they can leave the clinical setting.
Looking ahead at EMG in the continuum of care
For there to be effective convalescence after illness or injury, the patient must continue treatment and rehabilitation beyond the doors of the clinical environment. It is challenging to appropriately implement a continuum of care at home due to the absence of contact with medical professionals and often patient motivation or capability, as well as the economic and time constraints associated with regular trips to the clinic. Across the medical industry we can see telemedicine solutions taking an increasingly important role in continuing healthcare from the home. Our medical development team see that EMG has the potential to be a very effective complementary technology to telemedicine by providing medical professionals with real-time patient data to perform diagnoses and progress tracking during recovery and rehabilitation sessions.
Internet connected EMG sensors are ubiquitous in the research sector and can be expected to make an appearance in telemedicine if the next decade sees remote care develop traction; we can already see glucometers, oximeters, and blood pressure cuffs in use at home being accessed remotely by practitioners. There is every reason to believe that EMG sensor systems will be among these devices, assuming they can be designed in a commercially viable way - alongside the development of the supporting infrastructure - the market drive certainly exists.
Further down the line, rehabilitation robotics could develop into affordable, intuitive, safe devices in which integrated EMG sensors will allow for independent use at home. EMG can also be expected to play an increasingly important role as more advanced assistive devices, such as prosthetics, become more sophisticated and affordable.
Given our strong track record in medical devices and deep understanding of EMG technology, we would be pleased to talk to you about using EMG technologies in your healthcare solution, email us: [email protected].