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A new sniff-sensing device designed in Israel may help the severely paralyzed to communicate, surf the Net and steer their wheelchairs.

Sniffing is a precise motor skill that is controlled partly by the soft palate, which in turn is controlled by several nerves that connect directly through the braincase.

A stroke patient locked into her body for seven months unable to move or communicate was able to write an email to her family using a new device developed in Israel that allows severely disabled people to communicate and steer a wheelchair by sniffing.

The revolutionary new device identifies changes in air pressure inside the nostrils and translates these into electrical signals which can then be used either to write messages or to move a wheelchair.

"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," says Prof. Noam Sobel of the Weizmann Institute, who developed the device. "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."

Ability to sniff is preserved

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 braincase. 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) added support to the idea, showing that a number of brain areas contribute to soft palate 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, Sobel and his team, Dr. Anton Plotkin, Aharon Weissbrod and research student Lee Sela from the Weizmann Institute's Neurobiology Department, created a device with a sensor that fits on the opening of the nostrils and measures changes in air pressure.

For patients on respirators, the team developed a passive version of the device, which diverts airflow to the patient's nostrils.

Initial tests, carried out with healthy volunteers, showed 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.

The team found that the method of use is easily mastered, both by healthy volunteers and the disabled. Seventy-five percent of the subjects on respirators were able to control their soft palate movement to operate the device.

Simple to learn, cheap to produce

One patient who had been locked into his body after a traffic accident 18 years ago, wrote that the new device was much easier to use than one based on blinking. Another 10 patients, all quadriplegics, succeeded in operating a computer and writing messages through sniffing.

In addition to communication, the device can function as a steering mechanism for wheelchairs: Two successive sniffs 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, the researchers found that a patient paralyzed from the neck down could navigate a wheelchair through a complex route - sharp turns and all - as well as a non-disabled volunteer.

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.

Now Yeda Research and Development Company, the Weizmann's technology transfer arm, is exploring the possibility of commercializing the technology, which is not only simple to learn, but also relatively inexpensive to produce.

In future, Sobel, who has been involved in numerous studies related to the sense of smell, believes that this invention could also be useful in other areas, for instance as a control for a 'third arm' for surgeons and pilots.