Method and Apparatus for Measuring Limb Position Sense During Cyclic Limb Movement (20086)
INVENTION: Limb position sense (LPS) is the ability of a subject to detect the position of his/her arm or leg in space. During locomotion, limb position sense is regulated by sensory feedback to the nervous system from proprioceptors, which include cutaneous, vestibular, muscle and joint receptors. These propioceptors respond to locomotion and provide information on spatial positioning of the limbs. Such feedback is essential for the generation of the normal motor pattern, and can influence normal movement. Other research indicates that limb position sense becomes more acute with active movement and with multisegmental joint movement. Furthermore, results from other studies also show that the central nervous system processes the peripheral input differently at different points in a movement trajectory, and that LPS is althered during movement compared with static or near static positioning tasks. Currently, clinical measurement of proprioception is determined by two methods: single joint position placement and mirroring. These are static, single joint measurements that do not signify how proprioception effects movement. In addition, they do not directly test a person's ability to sense limb position during and ongoing functional movement, nor do they test LPS acuity during different phases in the trajectory of the movement. Recently, researchers at Northwestern University developed a method and a device that enable clinicians, for the first time, to match limb position sense acuity to actual functional movements. The methodology can be practiced using a modified standard pedaling ergometer (either arm or leg) equipped with a potentiometer or optical encoder. The advantages of the new methodology are illustrated in the following example. A blindfolded subject is given different positional targets of interest and asked to pedal on the ergometer. The subject is also instructed to give a vocal signal as soon as the subject feels that the target has been hit. The difference between the actual voice indicated position and the expected target position is calculated. This difference measurement can be used to compare normative values and also to indicate points in the movement trajectory where acuity is particularly impaired. This invention allows clinicians to better predict actual deficits in behavior, and to train individuals to improve LPS during an ongoing movement. It is even more critical for many athletes engaged in activities such as dancing, skating, gymnastics, pitching/throwing. Impaired LPS is thought to contribute to joint injuries and to conditions such as osteoarthritis. Furthermore, patients recovering from stroke and some kinds of surgeries must retrain their LPS in order to regain full range of motion.
FIELD OF APPLICATION: This invention is useful for neurobiologists, physical therapists, occupational therapists, health screeners etc. who diagnose, evaluate and/or train patients with impaired LPS.
ADVANTAGES: Allows measurement of LPS during functional movement of limbs. Can be used as an "add-on" to any existing bicycle or arm powered ergometer.
STAGE OF DEVELOPMENT: U. S. Patent No. 6,692,449 has issued and Northwestern is interested in licensing the technology for commercialization.
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