Spinal Nerve Injury

The spinal cord is the communications link between the brain and rest of the body. It’s encased in the spinal column and is generally divided into four sections. There are 8 cervical nerves (C), in the area of the spinal cord from the base of the brain to the lower neck/top of the shoulders. Twelve thoracic nerves (T) are located between the shoulders to the bottom of the upper back. In the lower back, there are 5 lumbar nerves (L). At the lower end of the spine, there are five sacral nerves(S).

When disease or injury damages the spinal cord, the communications link to the brain may be impaired or broken. The level of impairment is often divided into one of two categories. Paraplegia is used to describe spinal cord damage somewhere between the second thoracic nerve (called T2) and the last sacral nerve (S5). Depending upon the location of the injury, patients may lose movement and/or sensory function in the chest, stomach, hips, legs, feet or toes. Tetraplegia (formerly called quadriplegia) is damage anywhere from the top of the spine (C1) to first thoracic nerve (T1). People with tetraplegia may have a loss of movement and/or sensation in head, neck, shoulders, upper chest, arms, hands or fingers.

According to the National Spinal Cord Injury Statistical Center, about 255,700 Americans are living with a spinal cord injury. Roughly 12,000 new cases occur every year. Close to 80 percent of patients are male. The most common causes of injury are motor vehicle crashes, falls, acts of violence and sporting/recreational activities.

Wheelchair Use in the U.S.

When mobility is limited or not possible, a wheelchair may be used to help a person get around. There are two basic types of wheelchairs – manual and power (sometimes referred to as electric wheelchairs). Manual wheelchairs are designed to be pushed – either by the user or someone else. They are generally lightweight and easy to transport. But they require physical strength to make the wheelchair move. Power wheelchairs are battery powered, so they don’t require physical strength to operate. They are typically steered with a joystick.

Many people who can’t use a manual wheelchair are able to get around with a power wheelchair. However, people with tetraplegia and those who have no use of their hands are unable to operate the controls to move and turn a power wheelchair.

One currently available system uses a straw and sip-and-puff technique to steer a power wheelchair. A user either sucks or blows air through the straw. The direction and strength of airflow is picked up by a sensor and sent to a computer, which translates the actions into programmed movement. The sip-and-puff technique is simple to learn, but slow and cumbersome, and it can be difficult for a user to achieve smooth movements. Patients on a ventilator do not have the ability to move air in and out of a straw.

The Tongue Drive System

Researchers at Georgia Technical Institute of Technology are developing a new way for users to control power wheelchairs, using a technology called the Tongue Drive System. Engineering Researcher, Maysam Ghovanloo, Ph.D., says the system uses a small magnet attached to the end of the tongue. As the tongue moves in specific directions, sensors on an external headset detect the position of the magnet. The information is sent from a wireless transmitter on the headset to a computer, which translates the information into programmed signals for movement of the wheelchair.

In initial testing at the Shepherd Center in Atlanta, researchers found users could quickly learn how to use the tongue drive system to operate a power wheelchair. They could even navigate the wheelchair through an obstacle course.

The tongue drive system is still in development and testing. Eventually, Ghovanloo envisions the magnet will be incorporated into a tongue piercing and the sensors embedded in a retainer-like device. That would keep the entire system out of sight and enable users to invisibly operate their wheelchairs. Ghovanloo says most people with spinal cord damage could use a tongue drive system because the nerve that controls tongue movement is rarely damaged. The tongue is also a powerful muscle that doesn’t tire easily.

For general information on choosing or using a wheelchair:

American Occupational Therapy Association

United Spinal Association

For information on spinal cord injury:

National Institute Neurological Disorders and Stroke

National Spinal Cord Injury Statistical Center

ThinkFirst: National Injury Prevention Foundation