Inhale, exhale and move forward

New invention enables quadriplegics to maneuver.

By
July 28, 2010 03:28
3 minute read.
A VOLUNTEER in a wheelchair is seen attached to a nasal tube as he tries out the new breath-controll

wheelchair 311. (photo credit: Weizmann Institute)

Quadriplegics like England’s Prof. Stephen Hawking who have difficulty even pressing buttons or moving a joystick will be able to navigate their wheelchairs and communicate with others more easily by inhaling or exhaling through the nose at a sniffing device invented at the Weizmann Institute of Science.

Prof. Noam Sobel, electronics engineers Dr. Anton Plotkin and Aharon Weissbrod, and research student Lee Sela developed the technology in the Rehovot institute’s neurobiology department, which announced the achievement on Tuesday.

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The unique device could replace the more tedious technology of blinking one’s eyelids to choose letters and piece together words, use a computer or steer an electric wheelchair.

Sniffing technology, said the developers, might even be used in the future to create a sort of “third hand,” to assist healthy surgeons or pilots.

The new system identifies changes in air pressure inside the nostrils and translates these into electrical signals. After the device was tested on both healthy volunteers and quadriplegics, the results showed that the method is easily mastered.

Users were able to navigate a wheelchair around a complex path or play a computer game with nearly the speed and accuracy of a mouse or joystick.

“The most stirring tests were those we did with locked-in syndrome patients,” said Sobel.

“These are people with unimpaired cognitive function who are completely paralyzed – ‘locked into’ – their bodies.

With the new system, they were able to communicate with family members,and even initiate communication with the outside world. Some wrote poignant messages to their loved ones, sharing with them – for the first time in a very long time – their thoughts and feelings.”

Four of those who participated in the experiments are already using the new writing system, and the Weizmann Institute’s technology transfer arm, Yeda Research and Development Company, Ltd., is investigating the possibilities for developing and distributing the technology.

Sniffing is a precise motor skill that is controlled, in part, by the soft palate – the flexible divider that moves to direct air in or out through the mouth or nose. The soft palate is controlled by several nerves that connect to it directly through the skull. This close link led Sobel and his scientific team to theorize that the ability to sniff – that is, to control soft palate movement – might be preserved even in the most acute cases of paralysis.

Functional magnetic resonance imaging (fMRI) provided evidence behind the idea, showing that a number of brain areas contribute to softpalate control. This imaging revealed a significant overlap between soft palate control and the language areas of the brain, hinting to the scientists that the use of sniffing to communicate might be learned intuitively.

To test their theory, the researchers created a device with a sensor that fits on the nostril’s opening and measures changes in air pressure. For patients on respirators, they developed a different version of the device, which diverts airflow to the patient’s nostrils.

About three-quarters of the subjects on respirators were able to control their soft-palate movement to operate the device.

Initial tests, carried out with healthy volunteers, demonstrated that the device compared favorably with a mouse or joystick for playing computer games. In the next stage, carried out in collaboration with Prof. Nachum Soroker of Loewenstein Hospital Rehabilitation Center in Ra’anana, quadriplegics and locked-in patients tested the device.

One patient who had been locked in for seven months following a stroke learned to use the device over a period of several days, writing her first message to her family. Another, who had been locked in since a traffic accident 18 years earlier, wrote that the new device was much easier to use than one based on blinking. Another 10 quadriplegics succeeded in operating a computer and writing messages via sniffing.

The device can also function as a sort of steering mechanism for wheelchairs: Two successive sniffs in tell it to go forward, two out mean reverse, out and then in turn it left, and in and out turn it right. After 15 minutes of practice, a subject who is paralyzed from the neck down managed to navigate a wheelchair through a complex route – sharp turns and all.

Sniffs can be in or out, strong or shallow, long or short; and this gives the device’s developers the opportunity to create a complex “language” with multiple signals.

The new system is relatively inexpensive to produce, Sobel suggests, and simple and quick to learn to operate in comparison with other brainmachine interfaces.


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