Oculomotor performance in patients with neck pain: Does it matter which angle of neck torsion is used in smooth pursuit eye movement test and is the agreement between angles dependent on target movement amplitude and velocity?

Abstract

Background: Neck torsion manoeuvre is thought to affect eye movement control via afferent sensory drive in neck pain disorders patients. Literature reports inconsistencies regarding the angle of neck torsion most commonly used across the studies.

Objectives: The goal of this study was to determine the level of agreement in oculomotor performance between two most commonly used neck torsion angles during smooth pursuit neck torsion test (SPNT).

Design: A cross-sectional design was used in thirty-two neck pain patients and thirty-two healthy individuals.

Method: Gain and SPNT_diff were measured during SPNT test at 30° and 45° of neck torsion angle, at 30°, 40° and 50° of target movement amplitudes and three different target movement velocities (20°s^-1, 30°s^-1 and 40°s^-1) using eye tracking device. Bland-Altman plots and correlation analysis were used to study the agreement between the two angles.

Results: Small to medium correlations and wide bias confidence intervals suggest medium level of agreement in gain or SPNT_diff between the two neck torsion angles for chronic neck pain patients, but higher in healthy individuals. Higher agreement in gain was observed at lager target movement amplitudes and at slower target movement velocities, however this trend was not observed for SPNT_diff.

Conclusion: Level of agreement between the two angles in SPNT test depends on the amplitude and velocity of the moving target. In cases when subjects within the same study are not able to perform 45° of neck torsion, 50° amplitude and 20°s^-1 velocity of target movement are more suitable to reach higher agreement between the angles.

Keywords: Eye movement control; Neck pain; Proprioception; Smooth pursuit neck torsion test.