Abstract

Background:Neck pain accounts for a large part of western country´s total health care costs which emphasizes the need for effective rehabilitation interventions. There has in recent years been an increasing interest around the world to investigate the role of impaired neck sensorimotor control as a contributing factor to long term or recurring neck pain. There is however a lack of feasible and accurate objective methods for the assessment of movement behavior, including proprioception tests of the neck in the clinic today. The purpose of this observational study was to investigate test- retest reliability of such a test using a laser pointer and an automatic scoring system of the test results.

Methods:Sixty participants performed a tracking task of a zig-zag pattern in four different directions with a laser pointer attached to their head as accurately as possible at two different test occasions. Each trial was video recorded and analyzed with a specifically tailored image processing pipeline for automatic quantification of the test. The four main outcome variables were acuity, velocity, number of times off the target line and finally time to complete the test.

Results:The results of intra session repeatability between test occasion one and occasion two showed acceptable intra class correlation (ICC) values (0.67-0.76) for acuity and good to excellent for the other outcome variables (0.82-0.95). SEM values were quite high for all outcome variables, indicating that relative high values are needed to ensure that changes between measurement occasions are relevant. Wilcoxon signed ranks did not indicate any systematic bias with a learning effect for acuity, but for the other outcome variables it did.

Furthermore, there was a clear negative correlation between acuity and velocity, indicating a speed-accuracy trade off commonly found in manual tasks.

Conclusions:This study indicates that this specific test involving a tracking task of a zig-zag pattern with a laser pointer and automatic scoring of acuity from video recordings is a reliable and feasible test for assessment of sensorimotor control of the neck in the clinic. We suggest that further knowledge should be gained when the speed-accuracy trade off we found during the test are accounted for.

Keywords:Neck, Laser pointer, Proprioception, Tracking task

Chronic neck pain is associated with sensorimotor dysfunctions, which may develop symptoms, affect daily activities, and prevent recovery. Feasible, reliable, and valid objective methods for the assessment of sensorimotor functions are important to identify movement impairments and guide interventions. The aim of this study was to investigate the discriminative validity of a clinical cervical movement sense test, using a laser pointer and an automatic video-based scoring system. Individuals with chronic neck pain of idiopathic onset (INP), traumatic onset (TNP), and healthy controls (CON) were tested. Associations between movement sense and neck disability were examined and the repeatability of the test was investigated. A total of 106 participants (26 INP, 28 TNP, and 52 CON) were included in a cross-sectional study. Acuity, Speed, Time, and NormAcuity (i.e., normalized acuity by dividing acuity with movement time) were used as outcome measures. ANOVAs were used for group comparisons and Pearson correlations for associations between movement sense variables and neck disability index (NDI). Notably, 60 of the participants (30 CON, 17 INP, and 13 TNP) performed the test on a second occasion to explore test-retest reliability. Results revealed a reduced NormAcuity for both INP and TNP compared with CON (p < 0.05). The neck pain groups had similar Acuity but longer Time compared with CON. Among TNP, there was a fair positive correlation between Acuity and NDI, while there was a negative correlation between Acuity and NDI among INP. Reliability measures showed good to excellent ICC values between tests, but standard error of measurements (SEM) and minimal detectable change (MDC) scores were high. The results showed that NormAcuity is a valuable measure to identify disturbed cervical movement sense among INP and TNP. While Acuity was similar between the groups, different strategies, such as longer Time, to perform the task among neck patient groups were used. Few differences were identified between the neck pain groups, but altered strategies may exist. Reliability was acceptable, and the test is feasible to perform in the clinic. However, the technical complexity of the automated image analysis is a concern. Future developments will provide more feasible solutions.