Electro-oculographic measures in patients with chronic whiplash and healthy subjects: a comparative study.

BACKGROUND: Despite their high incidence, costs, and long lasting disability, whiplash associated disorders (WAD) lack an identifiable objective pathology that explains their acute or chronic symptoms. OBJECTIVE: In view of previous suggestions of a possible effect of neck torsion on several electro-oculography (EOG) parameters, the main objective of this study was to examine their applicability in differentiating patients from uninvolved subjects. METHODS: Smooth pursuit and saccadic eye movements were assessed in 26 patients with chronic WAD and 23 healthy subjects. All tests were executed in three neck positions: neutral and rotations to left and right. RESULTS: Neck torsion did not influence eye movement performance of either the WAD or healthy groups. However, compared with the healthy group, patients with WAD had significantly lower smooth pursuit velocity gain (SPVG) (p = 0.01) and prolonged saccadic latency (p = 0.001), irrespective of neck position. CONCLUSIONS: Despite scattered differences that reached significance, the electro-oculographic measures used in this study do not seem to offer a clinically relevant method for differentiating between patients with WAD and normal subjects.

Cervical circumduction in normal subjects: a study of maximal versus feigned effort.

The feasibility of using the coefficient of variation in conjunction with motion parameters derived from head circumduction to obtain a compact criterion for differentiating maximal from feigned cervical motion was evaluated. Twenty-five healthy subjects were measured twice during a period of 3 weeks using an ultrasonography-based motion analysis system. Subjects were asked to produce maximal motion of the spine as well as to feign limitation. Extracted from the displayed traces of head circumduction, the angular values of the primary motions of flexion, extension, right and left lateral flexion, as well as their additive score (AS) were determined. No test-retest differences were indicated. The average range of motion (ROM) was significantly smaller and the coefficient of variation of the ROM was significantly larger in the feigned compared with the maximal performance in both tests. However, tolerance interval analysis indicated that the coefficient of variation could not effectively separate between the effort levels, being particularly deficient with respect to AS. In addition, a differential sensitivity in identifying false-negative cases as a function of the movement paradigm was revealed. This study indicates that in healthy subjects, the use of a complex cervical movement such as circumduction cannot serve for differentiating between maximal and feigned performance using the coefficient of variation. The results may also point out the existence of a mechanism for adjusting proportional reductions among the primary cervical motions that result in excellent repeatability even in feigned efforts.

Maximal versus feigned active cervical motion in healthy patients: the coefficient of variation as an indicator for sincerity of effort.

STUDY DESIGN: Maximal and submaximal (feigned) cervical motions in healthy patients were compared. OBJECTIVE: To test the efficiency of the coefficient of variation in differentiating maximal (sincere) from submaximal (feigned) cervical motion in healthy patients. SUMMARY OF BACKGROUND DATA: Although limitation of cervical motion is a recognized impairment, no well-founded approach for verifying the degree to which a patient is maximizing his or her performance is available currently. METHODS: A new ultrasound-based system for three-dimensional motion analysis of the head was used to test 25 healthy patients (22 women and 3 men) ages 26 to 48 years. During the first test, (Test 1), the patients were asked initially to move the head maximally at a self-determined velocity in all the primary directions: flexion, extension, right and left rotation, and right and left lateral flexion. They then were presented with a short vignette describing a fictitious accident and asked, using the same protocol, to perform the same types of cervical motions as if they had experienced an injury. No further instructions were provided. A retest (Test 2) in reverse order (feigned effort first) took place 1 to 16 weeks (mean, 3.3 weeks) later. RESULTS: The range of motion and average velocity were significantly smaller (P = 0.0001) in the feigned than in the maximal performance in all directions and on both tests. Feigned range of motion and velocity also were significantly reduced in Test 2 (P = 0.006), as compared with those in Test 1 (P = 0.0001). The range of motion coefficient of variation in the feigned performance (CVf) remained stable on the retest, but was significantly larger on both tests (P < 0.001) than the corresponding CV derived from maximal performance (CVm). Furthermore, a case-by-case analysis showed that whereas the American Medical Association guidelines identified only 16% of the feigned cases, the use of CVf and CVm resulted in a corresponding rate of 87%. Tolerance intervals at 95% and 99% indicated total separation between the distributions of CVf and CVm, respectively. The average velocity-based CVf and CVm were not of a comparable differentiating power. CONCLUSIONS: This study indicates that in healthy patients, feigned performance may be differentiated from maximal (sincere) performance effectively and reproducibly using the coefficient of variation.

Reproducibility and instrument validity of a new ultrasonography-based system for measuring cervical spine kinematics.

OBJECTIVE: To report instrument validity of CMS 70P, a new ultrasonography-based system for spatial kinematic analysis of the spine and its application in studying the reproducibility of cervical motion findings in healthy subjects. BACKGROUND: Reproducibility of cervical motion has been investigated using various instruments and consisting in most cases of short test-retest time intervals of between minutes to days. METHODS: Performance of the instrument was validated against a digital inclinometer, at ranges of motion compatible with actual cervical motion. To study reproducibility, 25 healthy individuals, 22 women and 3 men aged 26-48 were tested twice within an average time interval of 3.3 weeks. Performed in the seated position and at a self-determined pace, cervical motion was defined in terms of head motion relative to a sternal (reference) system, in all six primary motions: flexion, extension, right rotation, left rotation, right lateral flexion and left lateral flexion. RESULTS: The system exhibited excellent agreement with the digital inclinometer, establishing its instrument validity for testing cervical motion. No significant differences were indicated between the test and retest for both the net maximal displacements and average velocities. The correlation coefficients for the single plane motions (e.g. flexion+extension) were higher than those derived for the primary motions, and ranged between 0.78 (sagittal plane) and 0.88 (frontal plane). The magnitude of the standard error of the measurement reflected the same trend with the lowest value recorded for the frontal plane. The self-selected velocity at which these motions were performed was similar in the frontal and saggital planes but was significantly higher for the transverse plane (rotations). CONCLUSIONS: This study indicates that spanned over time intervals that are measured in weeks, cervical motion findings derived from the CMS 70P are well reproducible. Findings also imply the need for a more stringent control of subject positioning and stabilization. RELEVANCE: Reduction of range of motion and average is typically observed in various pathologies of the cervical spine and is regarded, together with pain, as a major impairment. Therefore, valid assessment of cervical motion which is essential for follow-up and treatment outcome strongly depends on reproducibility of the findings. This study indicates that acceptable reproducibility is maintained over periods of time which are clinically meaningful using the system described herewith.