Evaluation of eye, head and trunk coordination during target tracking tasks

A pilot study on the evaluation of eye, head, and trunk coordination in subjects with chronic whiplash during a target-tracking task - A driving context approach

BACKGROUND

Motor vehicle accidents (MVA) are the most common causes of whiplash injuries. Difficulties with driving and changes in driving behavior are reported by subjects with chronic whiplash associated disorders (WAD). Proper eye and head coordination is required for driving tasks. Disturbances of eye and head coordination were found in these subjects with chronic WAD.

OBJECTIVES

The objective of this pilot study is to evaluate eye, head and trunk coordination in subjects with chronic WAD due to MVA and healthy controls during a target-tracking task using a functionally oriented approach in the context of driving.

DESIGN

Cross-sectional.

METHOD

The subjects performed target tracking tasks that reproduced eye and head movements required while driving. Head and trunk motion was captured using a motion capture system and eye movement was captured with an eye-tracker. Response time, time to target, and eye, head, and trunk contribution of movement were measured.

RESULTS/FINDINGS

Subjects with chronic WAD presented delayed response time and time to reach the targets with both eyes and head compared to the control group, and tended to compensate the lack of neck motion with increased eye motion.

CONCLUSIONS

This study shows indications of impairments of eye and head coordination in chronic WAD due to MVA when compared to healthy subjects. These alterations may have implications for driving safety.

Validation of Inertial Measurement Units for Upper Body Kinematics

The purpose of this study was to validate a commercially available inertial measurement unit (IMU) system against a standard lab-based motion capture system for the measurement of shoulder elevation, elbow flexion, trunk flexion/extension, and neck flexion/extension kinematics. The validation analyses were applied to 6 surgical faculty members performing a standard, simulated surgical training task that mimics minimally invasive surgery. Three-dimensional joint kinematics were simultaneously recorded by an optical motion capture system and an IMU system with 6 sensors placed on the head, chest, and bilateral upper and lower arms. The sensor-to-segment axes alignment was accomplished manually. The IMU neck and trunk IMU flexion/extension angles were accurate to within 2.9 ± 0.9 degrees and 1.6 ± 1.1°, respectively. The IMU shoulder elevation measure was accurate to within 6.8 ± 2.7° and the elbow flexion measure was accurate to within 8.2 ± 2.8°. In the Bland-Altman analyses, there were no significant systematic errors present; however, there was a significant inversely proportional error across all joints. As the gold standard measurement increased, the IMU underestimated the magnitude of the joint angle. This study reports acceptable accuracy of a commercially available IMU system; however, results should be interpreted as protocol specific.