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Artifact in Pediatric Oculomotor Findings during Videonystagmography: A Retrospective Analysis
Steven M Doettl1, Patrick N Plyler1, Devin L McCaslin2
1Department of Audiology and Speech Pathology, University of Tennessee Health Science Center, Knoxville, TN.
Background:
Accurate measurement of oculomotor function using videonystagmography (VNG) is imperative for diagnosis and management of patients with reported dizziness. The oculomotor evaluation during VNG utilizes video-oculography providing valuable information regarding the central structures and pathways that control eye movements. Artifact may have an effect on the overall validity and reliability of VNG oculomotor tracings and can result from patient and/or recording errors. It is postulated that artifact could occur more frequently in the pediatric population due to both patient and equipment factors.
Purpose:
The purpose of this study was to systematically evaluate the occurrence and impact of artifact on saccades, smooth pursuit, and optokinetic (OPK) testing in normal pediatric and adult subjects using commercially available clinical VNG equipment and standard clinical protocols for oculomotor testing.
Research Design:
The present study utilized a retrospective analysis of a repeated measures design.
Study Sample:
Oculomotor results from a total of 62 participants were analyzed. Portions of these data have been presented in a previous research study. Group 1 consisted of twenty-nine 4- to 6-yr-olds with an average age of 4.86 (SD = 0.88) yr. Group 2 consisted of thirty-three 22- to 44-yr-olds with an average age of 25.2 (SD = 5.34) yr.
Data Collection And Analysis:
Raw oculomotor recordings were analyzed "offline" by a single masked, trained investigator. Each tracing was evaluated for instances of artifact including eye blinks, eye closure, eyes moving in opposite direction of the target, eye tracking software problems, and overall poor morphology. The number of instances of artifact were noted and recorded for each participant in both groups. Individual eye movements not affected by artifact were included for final analysis. Artifact rejection techniques were also compared.
Results:
The results indicated increased artifact for the pediatric group for saccade and smooth pursuit testing. Additionally, a significant decrease in instances of artifact was noted with an increase in age in months for both saccade and smooth pursuit findings. OPK results did not indicate any significant difference in instances of artifact between the pediatric and adult groups or any decrease in instances of artifact with increasing age in the pediatric group. Artifact rejection technique did not have a significant effect on oculomotor measures for either age group.
Conclusions:
Pediatric patients exhibit increased instances of artifact during VNG oculomotor testing, specifically during saccade and smooth pursuit testing, at least for the 4- to 6-yr-old population. A general age effect was also noted in this age group, with decreased artifact noted with increasing age. Artifact rejection technique was not a significant factor suggesting standard compared based strategies may be sufficient for use in the pediatric population. Additional study into the effect of artifact on oculomotor results for infants to age 3 yr and ages 7- to 18-yr-old, in the disordered population, and with additional equipment manufacturers is needed to confirm these results and further describe the impact of artifact on oculomotor findings in the pediatric population.