Improving stimulated hand movement and gripping
Most of us take for granted the myriad of movements allowed by the complex network of muscles, tendons and nerves in our hands and arms. Not so the victims of spinal injury, particularly quadriplegics, who lose movement in all their limbs.
By far the most common victims of spinal cord injury are young men aged between 17 and 19 years. At a time when most people are beginning to assert some independence in their lives, the loss of function result from a high spinal cord injury increases dependence on others for even the most basic tasks.
Despite being highly disabled, people with quadriplegia have a predicted lifespan approaching non-injured persons.
To give them back some movement, however limited, is to restore a richly appreciated degree of independence over many years.
Leading the field in Australia, orchestrating research into improving stimulated hand movement, with a team of physiotherapists, hand surgeons, carers, biomedical engineers and research students, is Dr Tim Scott, an adjunct senior lecturer in Engineering at the University of Sydney, and Research Director of the Quadriplegic Hand Research Unit based at the Royal North Shore Hospital
"We have some great moments in the lab, when you see someone's hand move, which hasn't had that sort of movement for a long time," Dr Scott said. "It can get very emotional."
In time, Dr Scott hopes to be able to help victims of stroke and others with movement disorders, but he makes it clear the current focus is on helping those with spinal cord injury.
"We must carry out a lot of physiological testing, and the people have to be very motivated to get through the rehabilitation process successfully. With spinal injuries there is usually only one part of the body which is damaged, while the rest, although motionless, is often still intact and, with the right stimulus, capable of functioning."
Dr Scott recently returned from the US with a technological collaborative agreement that will allow him to undertake new clinical research using a 12-channel implanted stimulator device.
This will allow further innovative improvements to the provision of function to the hand and arm, and allow subjects to return home with a working hand which had been previously paralysed.
Through implantation, the device can provide grasp and release controlled by the user.
This state-of-the-art device is expected to build on movements already made possible with an eight-channel version, implanted and used successfully at Dr Scott's Unit since 1997.
"We have been fortunate to be able to send our subjects home with a working hand, enabling eating, drinking a glass of water, cleaning their teeth and combing their hair; basic every day tasks other people take for granted."
Hand surgeon, Dr Claudia Gschwind, and rehabilitation specialist, Dr Sue Rutkowski, provide medical support to the team. The hand surgery combines tendon transfers with electronic implants.
The surgeon moves still-active muscles into positions which allow the greatest amount of biomechanical function, while adding implants which can stimulate movements electronically.
Subjects can then use their shoulders to operate a joy stick which, combined with an external coil, triggers a range of movements in the opposite hand, while a microprocessor control box sits in their wheel chair.
Each device must be custom-fitted, carefully adapted to the subject's body and needs.
"We have been continuing research into hand function and implanted four people with these systems and they have worked beautifully."
Dr Scott graduated from the University with a degree in Science and Electrical Engineering, gained a PhD in physiology, also from Sydney, and won a fellowship from the Movement Disorder Foundation of Australia to work with world leader in the field of stimulating paralysed muscles using electricity, Professor Hunter Peckham of Case Western Reserve University in the US.
In a range of collaborative research projects, Dr Scott and PhD students have pioneered the implantation of bilateral systems, and have also been working on a variety of methods to improve hand function.
Muscle fatigue has also been under study, along with improvements in control of electronically stimulated hand grasps, much of the research supported by the Motor Accidents Authority of NSW.
Other research focuses on actuators, polymers developed at the University of Wollongong which shorten when a charge is applied, forming a type of artificial muscle. While they are not yet sufficiently developed to be implantable, they are being incorporated into an external glove, providing therapy through continuous passive movement, keeping the hand supple while allowing a "light pinch", particularly important following trauma, surgery, burns or paralysis.
"One of the most exciting aspects of our clinical research work is that we see the benefits of it in the clinic.
"Our team is small but specialised. It incorporates a mixture of people with strong clinical, engineering and research skills - the key to our success so far."
