The POSSUM system | Action Medical Research

Touching Lives - September 2004

The POSSUM system

There’s never been a good time to sustain a spinal injury, with all the life-changing consequences entailed. But your chances of rehabilitation and of leading a normal, independent life are better now than they’ve ever been, thanks in part to forward thinking grants awarded by Action Medical Research in the 1960s.

One man who was closely involved in the revolution of care for spinal injury patients is Dr John Silver. In 1955 he was sent to work at Dr Ludwig Guttmann’s pioneering National Spinal Injuries Centre at Stoke Mandeville Hospital.

Dr Silver takes up the story: “Guttmann’s unit was a fantastic place to work. He was a hugely exciting and stimulating man to work for. You did feel like you were in the middle of something special. It was a youthful environment to work in because the patients tended to be young. And because Guttmann himself was a refugee [from Nazi Germany — Ed.] he tended to employ other refugees. It certainly wasn’t the usual straight-laced environment you found in teaching hospitals at the time!”

Athletes in wheelchairs

Action Medical Research funded Dr Silver in 1962 to investigate the physiology of spinal injury patients. “So much was unknown about spinal injury patients at the time — how their bodies regulated temperature, how their breathing mechanisms were affected, how their bodies regulated salt and water. A broken spinal cord affects so many of the body’s natural mechanisms. My research helped our understanding, and did affect how patients were managed.”

The Charity also funded Dr Guttmann in his pioneering work to rehabilitate patients through sport. Though some disabled First World War veterans took part in sports activities at the famous Royal Star & Garter Home, it was Guttmann who did the most to bring disabled athletics into being. Before then the idea of athletes in wheelchairs was pretty much unfathomable. But it took off!

In 1948 Guttmann organised the first competition for his patients. Four years later competitors from Holland joined the games and the international movement, now known as the Paralympics, was born. Olympic style games for athletes with a disability were organised for the first time in Rome in 1960.

I am able

Thus Action Medical Research was closely involved as Stoke Mandeville began to acquire its worldwide reputation for clinical excellence. In 1961 the Charity funded two other researchers, Reg Maling and Derek Clarkson, to develop POSSUM — or ‘Patient Operator Selector Mechanisms’. Happily, ‘Possum’ in Latin means ‘I am able’.

Messrs Maling and Clarkson observed that patients at Stoke Mandeville lay in their beds, totally paralysed and unable to attract the attention of medical staff except by blowing a whistle hanging over their beds. They felt that if patients were able to control the air in their mouths enough to blow on a whistle, then the same process could be used to operate micro-switches and thereby enable them to control any number of electrical appliances. In fact, from a mechanical point of view, the mouth is a remarkably good pneumatic controller, capable of very precise applications of pressure.

“We were delighted with the grant,” says Reg, now aged 76. “It meant that we were able to make much more rapid progress than would otherwise have been possible.” Within six months of the grant award the first POSSUM instrument was made, giving the patient control over bells, lights, radios, telephones and televisions.

As the technology was refined, so more advanced applications were implemented, such as the POSSUM ‘sip-and-puff’ typewriter, and the technology was internationally recognised, winning major scientific awards. “We made a real difference,” Reg continues. “I remember one lady who had literally only a flicker of movement in one toe. She went on to write a beautiful book of poems — it was quite extraordinary.”


It was realised that there was a great need for this type of equipment to rehabilitate patients and to allow them the greatest possible degree of independent living. A company was set up to develop and manufacture the equipment, and this company, Possum Controls Ltd, still exists today, providing innovative products to enhance the quality of life of disabled people.

“Maling and Clarkson were at the cutting edge,” confirms Dr Silver. “They were the first in the field, and they revolutionised patients’ lives. Action Medical Research put in one of its biggest grants at the time to allow them to make this vital contribution to the rehabilitation of spinal injury patients.”

Action Medical Research is proud of its long association with the world-leading National Spinal Injuries Centre at Stoke Mandeville, and continues to fund research there to this day.

Dr John Silver’s book ‘History of the Treatment of Spinal Injuries’ is published by Kluwer.

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