1. Background/Objective
A Comparison of Neuropsychological and Balance Performance Validity Testing
Patrick Armistead-Jehle, Ph.D., ABPP-CN1, Beth J. Lange, MD, FRSCS (C)2, Paul Green, Ph.D3.
1Fort Leavenworth, KS, 2Calgary, Canada, 3Alberta, Canada
Background/Objective
Performance validity testing in the context of neuropsychological assessment is well established. While such measures are also available with balance testing; little research has investigated these two domains in concert. The purpose of this study was to compare scores on two measures of performance validity across cognitive and balance modalities.
Computerized Dynamic Posturography (CDP). One’s ability to maintain balance results from the integration of inputs from the visual, somatosensory, and vestibular systems. CDP is an assessment technique that separates the influences of each of these systems in examinees with reported balance and dizziness problems. With CDP testing, the examinee stands on a movable surface that is located within a modifiable enclosure. Via standardized programs the surface can move within a horizontal plane and thus alter the angle on which the examinee stands; while the enclosure can be altered to manipulate the visual surround of the examinee. Standard protocols subject the examinee to different variations of support surface and/or visual stimuli and subsequently measure postural stability and motor reactions. With such conditions there is a gradient of difficulty that when violated suggest symptom exaggeration (for example Figure 1). For the current study Invalid CDP performance was determined using the Goebel et al (1997) criteria, suggesting an aphysiologic (non-organic) response.
Methods
A retrospective chart review was conducted on 78 subjects (92% male; average age = 44.5 years; [SD = 12.7]) seen independently by both a neuropsychologist and an otolaryngologist in the context of disability evaluations. Diagnostically, 47 subjects had a remote history of mild TBI, 21 had a remote history of moderate to severe TBI, 3 had remote histories of TBI of unknown severity, and 7 had other orthopedic or neurologic diagnoses. Each patient was administered the Word Memory Test (WMT) and completed standard protocols for Computerized Dynamic Posturography (CDP).
Image courtesy of Natus Medical Incorporated
Figure 1. The six conditions of the CDP Sensory Organization Test. The ability to maintain balance is increasingly difficult with each condition.
Conclusions
These results are among the first to demonstrate that symptom exaggeration crosses modalities within a compensation seeking sample. The data suggest that if symptom exaggeration occurs within one modality other modalities may also be exaggerated and should be independently evaluated.
Results
Thirty-nine subjects passed each measure and 16 failed each. Eleven subjects failed the WMT, but passed the CDP, while 12 subjects passed the WMT but failed the CDP. There was a 70.5% agreement between these two measures, which were significantly correlated (r= 0.35, p=.002). Chi-squared was statistically significant (χ2 = 9.8, p=.002).
Measures
Word Memory Test (WMT). The WMT is a computer administered test with multiple subtests designed to assess performance validity . Twenty semantically related work pairs are presented twice for examinees to learn. Directly after the learning trials Immediate Recognition (IR) memory is tested. Following a delay, Delayed Recognition (DR) memory is assessed. This is then followed by a serious of subtests comprising multiple choice, paired associate, and free recall formats. In addition to these five subtests, a consistency (CNS) score is calculated to gauge recall consistency across select trials. Failure on the WMT was defined as performance below the cut score on the IR, DR, and/or CNS subtests as defined in the test manual (Green, 2003).
References
Green, P. (2003). Green's Word Memory Test for Windows: User's manual. Edmonton, Canada: Green's Publishing.
Goebel, J.A., Sataloff, R.T., Hanson, J.M., Nashner, L.M., Hirshout, D.S. & Sokolow, C.C. (1997). Posturographic evidence of nonorganic sway patterns in normal subjects, patients, and suspected malingerers. Otolaryngology- Head and Neck Surgery, 117,
WMT – Pass
WMT - Fail
CDP – Pass 39 11
CDP - Fail 12 16
The views, opinions, and/or findings contained in this research are those of the authors and should not be construed as official Department of the Army or Department of Defense positions, policies, or decisions unless so designated by other official documentation