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PROPRIOCEPTIVE ACUITY IN THE ABSENCE OF SENSORY FEEDBACK USING AN ISCHEMIC NERVE BLOCK

K Lee
L Ettinger

Abstract

K. Lee, L. Ettinger

Willamette University, Salem, OR

PURPOSE: Our laboratory was the first to document proprioceptive disruption in patients with Type II Diabetes Mellitus (T2DM) with and without peripheral neuropathy (PN). The cause of proprioceptive disruption is unknown. Evidence suggests two likely mechanisms involving the sensory receptors and nerves as well as cerebral disruption altering the processing of sensory information are likely in this population (Ryu 2019, Ettinger 2018). Separating the afferent signaling from the processing would give insight as to which mechanism is more likely disrupted in patients with T2DM. In the present study, an ischemic nerve block was used to disrupt the generation of afferent signals while the processing of sensory information was unmanipulated. We hypothesized that during the block, non-diabetics would demonstrate proprioceptive errors that were consistent with those measured in patients with T2DM. METHODS: A tourniquet block (40 mmHg above systolic blood pressure), was imposed on the brachium of 5 non-T2DM participants (21.5 years). A magnetic tracking device (Polhemus Fastrak, Colchester, VT) was used for measuring arm motion. For joint position sense (JPS) subjects were outfitted with a head-mounted display, which allowed the subjects to see a virtual representation of the target position while preventing visual feedback from their hand. Target angles 50°, 70°, and 90° of shoulder elevation were selected. All targets were repeated 4 times and were randomized. The center of the screen contained a box representing a ±1° boundary of the target. The arm was virtually represented as a red dot. The subject was then asked to hold the red dot in the target and then memorize the “location of their arm in space.” Afterwards the participant was asked to return to where the perceived target location was. All methodology for JPS testing was repeated between the ischemic and control conditions which were randomized prior to participation. RESULTS: Preliminary results indicate higher proprioceptive errors in the ischemic conditions at most target angles.

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