July 27, 2010
‘Sniffing’ Technology Helps Disabled Move, Communicate
Doctors in Israel have developed a unique "sniffing" controller that allows people with severe disabilities to use their noses to write, surf the Web, and even navigate their wheelchairs.
The new technology might even be used in the future to create a sort of 'third hand' to assist healthy surgeons or pilots.
The device uses a "sniffing technology" that measures pressure changes in the nose from breathing in and out, and then translates these changes to electrical signals.
When tested on both healthy and quadriplegic volunteers, the system was easily mastered, with users easily able to drive a wheelchair around a complex path or play a computer game with nearly the same speed and accuracy of a mouse or joystick.
"The most stirring tests were those we did with locked-in syndrome patients. These are people with unimpaired cognitive function who are completely paralyzed "“ 'locked into' their bodies," said Noam Sobel, a professor of neurobiology at the Weizmann Institute in Rehovot, Israel.
"With the new system, they were able to communicate with family members, and even initiate communication with the outside. Some wrote poignant messages to their loved ones, sharing with them, for the first time in a very long time, their thoughts and feelings."
Sobel worked with other scientists from the Weizmann Institute and the Sackler faculty of medicine at Tel Aviv University to develop the new system.
The soft palate, the flexible divider that moves to direct air in or out through the mouth or nose, is controlled by cranial nerves that are "always very well conserved following severe injury," Sobel told the AFP news agency.
"That's why eye blinks can be used to communicate with severely injured people -- because eye blinks are also controlled by cranial nerves."
Since sniffing is a precise motor skill that is controlled, in part, by the soft palate, Sobel and his team theorized that the ability to sniff, or to control soft palate movement, might also be preserved even in the most acute cases of paralysis.
Functional magnetic resonance imaging supported their hypothesis, revealing that a number of brain areas contribute to soft palate control. The imaging showed a significant overlap between soft palate control and the language areas of the brain, suggesting that the use of sniffing to communicate might be intuitively learned.
To test their theory, the scientists created a device with a sensor that fits on the opening of the nostril and measures air pressure changes. For patients using respirators, the team developed a passive version of the device that diverts airflow to the patient's nostrils.
Preliminary tests showed that roughly three-quarters of the subjects on respirators were able to control their soft palate movement to operate the device. Tests with healthy volunteers showed that the device performed comparable with a mouse or joystick for playing computer games.
Professor Nachum Soroker of Loewenstein Hospital Rehabilitation Center in Raanana led the next stage of testing, in which quadriplegics and locked-in patients used the device.
The results were remarkable. 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.
She "started writing with this device at once, initially answering questions and after a few days generated her first post-stroke meaningful self-initiated communication that entailed a profound, personal message to her family," wrote the scientists in a report about the system published Monday in the Proceedings of the National Academy of Sciences.
Meanwhile, another patient who had been locked in since a traffic accident 18 years ago and was only able to communicate by blinking one eye was able to write his name within 20 minutes of being fitted with the device.
Another volunteer, a quadriplegic woman with severe multiple sclerosis, was able to write for the first time in 10 years. She also used the sniff-controller to move a cursor on a computer screen by sniffing, and now surfs the Web and write emails, wrote the scientists in their report.
"This device allowed us to communicate with very severely disabled individuals, even with individuals who could not blink," Sobel told AFP.
"We had one patient who couldn't blink at all and she sends us emails now by sniffing. That's pretty moving," he said.
Ten additional quadriplegic patients who took part in the tests were also able to operate a computer and write messages through sniffing.
The researchers were so encouraged by the results that they decided to devise a code to allow the sniff-controller to navigate an electric wheelchair.
In this case, two successive sniffs instruct the wheelchair to move forward, while two outward sniffs signal a reverse instruction. An outward sniff followed by an inward sniff tells the wheelchair to turn left, while in and then out turns it right.
Ten non-disabled volunteers easily navigated the sniff-driving wheelchair through a complex route, while a 30-year-old man who had been paralyzed from the neck down for six years performed just as well as the healthy participants by his second attempt, the report said.
"In other words, a quadriplegic person could use the sniff controller to drive an electric wheelchair with high precision following a total of only 15 minutes of practice," the authors wrote in their report.
The sniff-controller can interpret sniffs as in or out, strong or shallow and long or short, allowing a large enough number of combinations to create a complex 'language' with multiple signals.
Additional benefits of the system include its relatively low production costs, and its ease of use when compared with other brain-machine interfaces.
However, sniff-controlled technology is still in the development phase.
But if and when the device goes to commercial production, it would be very accessible to people, said Sobel.
The Weizmann Institute has already applied for a patent on the device.
"It should cost 10 or 20 dollars, not more," he told AFP.
"I'll be very happy if they make a buck but the real issue is, I hope someone will license it and develop it because this should go out into the world and help a lot of people."
"It's low-tech and simple, which is one of the things I like most about it."
On the Net:
- The full report, published Monday in the Proceedings of the National Academy of Sciences, can be viewed here.
- Weizmann Institute
- Tel Aviv University