NASA Spinoff

Medical Devices Assess, Treat Balance Disorders

Originating Technology/NASA Contribution

You may have heard the phrase “as difficult as walking and chewing gum” as a joking way of referring to something that is not difficult at all. Just walking, however, is not all that simple—physiologically speaking. Even standing upright is an undertaking requiring the complex cooperation of multiple motor and sensory systems including vision, the inner ear, somatosensation (sensation from the skin), and proprioception (the sense of the body’s parts in relation to each other). The compromised performance of any of these elements can lead to a balance disorder, which in some form affects nearly half of Americans at least once in their lifetimes, from the elderly, to those with neurological or vestibular (inner ear) dysfunction, to athletes with musculoskeletal injuries, to astronauts returning from space.

The effects of space flight on astronauts’ ability to balance has long been a focus of NASA research. This 1964 photo shows a NASA scientist testing astronaut John Glenn’s inner ear balance mechanism by running cool water into his ear and measuring the effect on Glenn’s eye motions.
Readjusting to Earth’s gravity has a significant impact on an astronaut’s ability to balance, a result of the brain switching to a different “model” for interpreting sensory input in normal gravity versus weightlessness. While acclimating, astronauts can experience headaches, motion sickness, and problems with perception. To help ease the transition and study the effects of weightlessness on the body, NASA has conducted many investigations into post-flight balance control, realizing this research can help treat patients with balance disorders on Earth as well.

In the 1960s, the NASA-sponsored Man Vehicle Laboratory at the Massachusetts Institute of Technology (MIT) studied the effects of prolonged space flight on astronauts. The lab’s work intrigued MIT doctoral candidate Lewis Nashner, who began conducting NASA-funded research on human movement and balance under the supervision of Dr. Larry Young in the MIT Department of Aeronautics and Astronautics. In 1982, Nashner’s work resulted in a noninvasive clinical technique for assessing the cooperative systems that allow the body to balance, commonly referred to as computerized dynamic posturography (CDP). CDP employs a series of dynamic protocols to isolate and assess balance function deficiencies. The technology was based on Nashner’s novel, engineering-inspired concept of balance as an adaptable collaboration between multiple sensory and motor systems. CDP proved useful not only for examining astronauts, but for anyone suffering from balance problems. Today, CDP is the standard medical tool for objectively evaluating balance control.


In 1984, Nashner founded NeuroCom International Inc., headquartered in Clackamas, Oregon, and continued his research to refine the clinical role of CDP. Within 2 years, the company had developed the EquiTest, the first commercially available CDP device. NASA has employed NeuroCom’s CDP systems for its research and continues to use EquiTest for the routine evaluation and balance rehabilitation of its astronauts at Kennedy Space Center and Johnson Space Center. NeuroCom’s EquiTest and Balance Master systems—the latter created based on CDP concepts to meet increasing demand from physical therapists—were first featured in Spinoff 1996.

“When I joined NeuroCom in 1988, the concepts of a systems approach to balance and vestibular rehabilitation were basically unknowns,” says Jon F. Peters, Ph.D., NeuroCom’s vice president and general manager. “Researchers were keen on the ideas, but it wasn’t common practice. Out of Dr. Nashner’s work grew a whole new approach for looking at these problems.”

Product Outcome

NeuroCom now has over 2,000 systems in use around the world in a variety of medical fields including neurology, geriatrics, otolaryngology (ear, nose, and throat specialists), orthopedics, and sports medicine.


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