Effects of Type II Diabetes on Proprioception during a Reach to Pinch Task

Abstract

Older adults with type II diabetes (T2D) are at risk of developing nerve disorders that result in functional impairment. Most work in proprioceptive dysfunction in older adults with T2D has focused on functional deficits of the lower limb. The purpose of this study was to examine proprioceptive effects of T2D on the upper limb in older adults. Kinematic performance of a reach-to-pinch action toward a virtual target was assessed in a T2D group (60+ years old with T2D) and a healthy age- and sex-matched control group. Tactile and vibratory thresholds did not differ between T2D and controls. Task accuracy via mean pinch location was significantly worse for persons with T2D (pwT2D) with differences in wrist extension/flexion (ex/fl), wrist abduction/adduction (ab/ad), 1st carpometacarpal (CMC) ab/ad, 2nd metacarpophalangeal (MCP2) ex/fl, MCP2 ab/ad, and digit 1 and hand transport trajectories. Group differences persisted with consideration of body mass index; sex differences in task accuracy emerged. Findings indicate that proprioception of the upper extremity is altered in pwT2D such that they exhibit a unique aperture position and aiming strategy during a reach-to-pinch action. These findings characterize functional sensorimotor impairment of the upper limb in pwT2D with respect to workspaces without visual or tactile feedback.

Keywords: aging processes; kinematics; motor control; tactile; virtual environments.

Figure 1:

A) Close up view of hand marker placement with 6.4 mm spherical reflective markers. One marker each was located at the very tip of the distal phalanx of digit 1 and the very tip of the distal phalanx of digit 2. Two markers were placed on each side of the CMC, MCP1, IP1, MCP2. PIP2, and DIP2 joints. A “T” shaped marker cluster on the second metacarpal was used as a local hand reference coordinate system. B) Front view of set up of the reach-to-pinch task. Subjects viewed a virtual target in a mirror while performing a reach-to-pinch movement with their hand. The maneuver is performed without visual feedback of the moving arm and hand. C) Marker placement of the right arm and hand. In addition to hand markers, markers are located at right acromioclavicular joint, the lateral epicondyle, and the radial and ulnar styloid processes. D) View of virtual target and mirror setup.

Figure 2:

Comparison of mean ± SD of joint angles and coefficient of variation (CV) of mean joint angles between T2D and Control groups. Data are presented as: flexion (+), extension (−), adduction (+), and abduction (−). Significance at a minimum of p < 0.05 is denoted by *.

Figure 3:

Digit and hand path length accumulated over the pinch cycle; distances self-normalized by subject palm with, as per Nataraj et al., 2014. A) Mean digit 1 trajectory ± 1 SD. Blue lines indicate control data; red indicate T2D. B) Mean digit 2 trajectory ± 1 SD. C) Mean hand trajectory ± 1 SD. D) Coefficient of variation (CV) of end-point spatial location in the x-, y-, and z-directions for Control and T2D groups.

Figure 4:

Accuracy and aperture data. A-C) Mean endpoint pinch aperture and location for individual and mean T2D and Control subjects with respect to the virtual target location (grey). Center of each sphere indicates pinch contact location while the radius indicates pinch precision (+1 SD) about pinch contact location. + x forward, + y leftward, +z upward, relative to virtual target. D) Average aperture across the task, separated by males and females. The gray 20mm line indicates the target size. E) Aperture at pinch location, separated by males and females. The gray 20mm line indicates the target size. Significance at a minimum of p < 0.05 is denoted by *.