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Powered wheelchair users, who are paralyzed from the neck down, can control their chair by sipping or puffing air into a straw mounted on their wheelchair to execute four basic commands that drive the chair. But, a new assistive technology, called the Tongue Drive System, can allow users to access computers and execute commands for their wheelchairs at speeds that were significantly faster than those recorded in sip-and-puff wheelchairs, but with equal accuracy.

The Tongue Drive System is controlled by the position of the user’s tongue. A magnetic tongue stud lets them use their tongue as a joystick to drive the wheelchair. Sensors in the tongue stud relay the tongue’s position to a headset, which then executes up to six commands based on the tongue position.

The research team had subjects complete a set of tasks commonly used in similar clinical trials. They compared how able-bodied subjects were able to execute commands either with the Tongue Drive System or with a keypad and mouse. For example, targets randomly appeared on a computer screen and the subjects had to move the cursor to click on the target. Scientists are able to calculate how much information is transferred from a person’s brain to the computer as they perform a point-and-click task. The performance gap narrowed throughout the trial between the keypad and mouse and the Tongue Drive System.

For the first time, the research team showed that people with tetraplegia can maneuver a wheelchair better with the Tongue Drive System than with the sip-and-puff system. On average, the performance of 11 subjects with tetraplegia using the Tongue Drive System was three times faster than their performance with the sip-and-puff system, but with the same level of accuracy, even though more than half of the patients had years of daily experience with sip-and-puff technology.

The idea for piercing the tongue with the magnet was the inspiration of Anne Laumann, MD, professor of dermatology at Feinberg and a lead investigator of the Northwestern trial. She had read about an early stage of Tongue Drive System using a glued-on tongue magnet. The problem was the magnet fell off after a few hours and aspiration of the loose magnet was a real danger to these users.

Experiments on the Tongue Drive System to date have been done in the lab or hospital. In future studies, scientists will test how the Tongue Drive System performs outside of the controlled clinical environment. The research team hopes to test how patients maneuver with the Tongue Drive System in their homes and other environments.

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