Posturographic performance in patients with the potential for secondary gain

Posturographic performance in patients with the potential for secondary gain GERARD GIANOLI, MD, SEAN MCWILLIAMS, BS, JAMES SOILEAU, MD, and PETER BELAFSKY, MD, PhD,

New Orleans and Baton Rouge, Louisiana

OBJECTIVES: To determine the incidence of nonorganic sway patterns on computerized dynamic posturography (CDP) among patients with potential secondary gain compared with patients without any obvious secondary gain. METHODS: A retrospective chart review of 100 patients who underwent clinical evaluation, audiometry, electronystagmography, and CDP was undertaken. Group 1 consisted of 50 patients who were randomly selected from a group who had pending lawsuits, worker’s compensation claims, or disability claims. Group 2 consisted of 50 randomly selected patients who had no pending legal status, worker’s compensation claims, or disability claims. Previously published criteria for nonorganic sway patterns were then applied to each group. Statistical analysis was performed. RESULTS: The average age of group 1 patients was 43.8 years compared with 63.2 years for group 2 patients (P < 0.0001). Among group 1 patients 50% had normal audiovestibular evaluations compared with only 4% of group 2 patients (P < 0.0001). Nonorganic sway patterns were found in 76% of group 1 patients, but only in 8% of group 2 patients (P < 0.0001). CONCLUSION: Patients who have the potential for secondary gain are generally younger and have a much higher prevalence of normal audiovestibular evaluations and a much higher prevalence of nonorganic sway patterns on CDP. A high degree of clinical suspicion should be maintained when evaluating the dizzy patient who has a pending lawsuit,

From the Department of Otolaryngology–Head and Neck Surgery, Tulane University Medical School (Drs Gianoli and Belafsky and Mr McWilliams). Dr Soileau is in private practice Baton Rouge, LA. Presented at the Annual Meeting of the American Academy of Otolaryngology–Head Neck Surgery, San Antonio, TX, September 13-16, 1998. Reprint requests: Gerard J. Gianoli, MD, Department of Otolaryngology–Head and Neck Surgery, Tulane University Medical School, 1430 Tulane Ave, SL-59, New Orleans, LA 70112-2699. Copyright © 2000 by the American Academy of Otolaryngology– Head and Neck Surgery Foundation, Inc. 0194-5998/2000/$12.00 + 0 23/1/98916

worker’s compensation claim, or disability claim. (Otolaryngol Head Neck Surg 2000;122:11-8.) Malingering . . . is the false and fraudulent simulation or exaggeration of physical or mental disease or defect, performed in order to obtain money or drugs or to evade duty or criminal responsibility, or for other reasons that may be readily understood by an objective observer from the individual’s circumstances, rather than from learning the individual’s psychology.—W. F. Gorman1

D

izziness is a frequent chief reported symptom for patients presenting to otolaryngologists and primary care physicians. According to the National Ambulatory Medical Care Service, nearly 8 million patients were seen by all physicians for dizziness in 1985.2 In a 1989 study3 dizziness was found to be the third most common symptom bringing patients to the physician’s office. Dizziness has been found to increase in prevalence with aging and has been found to be the most commonly reported symptom among patients 75 years of age and older.4 Dizziness is also frequently reported by litigants who have had accidental or job-related injuries. Worker’s compensation claims, disability claims, and lawsuits are filed for financial compensation because of this symptom. The difficulty in objective evaluation of dizziness and the specter of monetary compensation can lead to exaggeration of the severity of symptoms or to frank malingering. Objective measures of vestibular function, such as electronystagmography (ENG) and rotational studies, have been helpful in demonstrating organic lesions of the vestibulo-ocular reflex in such patients. However, they do not answer the question of whether the lesions were preexisting and whether there is any symptom magnification. Conversely, a normal ENG and normal rotational studies do not measure every aspect of the vestibular system and cannot eliminate the possibility of a vestibular lesion. Computerized dynamic posturography (CDP) has been used as a tool to measure the vestibulospinal reflex arc of the vestibular system.5 Recent studies have demonstrated that CDP is useful in evaluating suspected malingerers.6-9 Specific patterns of aphysiologic per11

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Table 2. Initial clinical diagnosis before testing Diagnosis

Group 1 (%)

Group 2 (%)

74 16 8 0 2

32 44 16 2 6

Dizziness of unknown cause* BPPV* Unilateral vestibular lesion Perilymphatic fistula Meniere’s disease BPPV, Benign paroxysmal positional vertigo. *P < 0.05.

Fig 1. Audiometric evaluations (P < 0.05).

Table 1. SOTs

Platform

Eyes open

Eyes closed

Swayed visual reference

Fixed Swayed

1 4

2 5

3 6

formance, nonorganic sway, or physiologically inconsistent performance have been identified. Prior CDP studies have evaluated these patterns typically by comparing the performance of patients with known vestibular lesions and healthy volunteers who had been asked to feign dizziness during testing. To the best of our knowledge, no one has ever evaluated the incidence of these patterns in a population of patients who have a monetary incentive for poor performance. The purpose of this study was to (1) compare the prevalence of aphysiologic sway patterns in a group of patients reporting dizziness who had a monetary incentive for poor performance and (2) determine the impact of secondary gain on CDP performance. METHODS AND MATERIAL This study was a retrospective analysis of 100 patients chosen randomly from our files by one of the authors (S.M.), a medical student who was unfamiliar with any of the patients and who was blinded to the CDP results during chart selection. Of these, 50 patients (group 1) had pending lawsuits, worker’s compensation claims, or disability claims. The other 50 (group 2) had no known legal claim or other identifiable opportunity for secondary gain. Additionally, the patients met the following criteria for inclusion in the study: (1) clinical

evaluation by history and physical examination, (2) chief reported symptom of dizziness or vertigo, (3) completion of CDP, audiometry, and ENG. Patients were excluded if they lacked complete information. Information analyzed from the chart included age, sex, initial clinical diagnosis after history and physical examination, and audiometry, ENG, and CDP results. Additionally, all patients had undergone radiographic evaluation with MRI and/or CT with no significant abnormalities identified in either group. Basic comprehensive audiometry was performed in all patients. Results were listed as normal for all patients who had either normal scores or symmetric hearing loss. An asymmetric hearing loss on either pure-tone testing or speech discrimination testing was listed as being abnormal. Asymmetric pure-tone scores were defined as more than 2 consecutive octave frequencies on pure-tone testing with a ≥15-dB difference in results. Asymmetric speech discrimination was defined as a difference of ≥ 15% between ears. ENG testing was evaluated separately by caloric testing and noncaloric testing. Unilateral weakness > 25% or directional preponderance > 30% was considered an abnormal test result for ENG caloric testing. The noncaloric testing consisted of spontaneous, gaze, saccade, pursuit, positional, and DixHallpike tests. If any abnormalities were noted on these tests, the results of the ENG noncaloric testing were considered abnormal. CDP was performed in accordance with instructions detailed by Nashner.10 All tests were performed on an Equitest System (NeuroCom International). Sensory organization test (SOT) protocols were analyzed for comparison between groups (Table 1). All patients completed 3 trials of each SOT. Scores for performance were recorded for each individual SOT as well as an average score for each subtest and a composite score for the entire testing session. The motor coordination test was not evaluated for comparison between groups in this study because of the difficulty in quantifying this information. CDP results were analyzed by the criteria listed below. Normal scores were obtained from the 1991 EquiTest System Data Interpretation Manual. 1. Mean SOT performance scores for all 3 trials on each scenario.

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Fig 2. ENG results: Caloric testing (left) and noncaloric testing (right) (P < 0.05).

2. Substandard performance on SOTs 1 and 2. 3. Goebel formula9 for comparison of SOTs 1 and 2 and SOTs 5 and 6. This was an analysis to determine better performance on the more difficult trials of SOTs 5 and 6 compared with SOTs 1 and 2. The formula for comparison was as follows: [(SOT 1 – Norm 1) + (SOT 2 – Norm 2)] – [(SOT 5 – Norm 5) + (SOT 6 – Norm 6)]. 4. Comparison between scores on SOTs 1 and 2 and SOTs 5 and 6 by the following formula: (Av SOT 1) + (Av SOT 2) – (Av SOT 5) + (Av SOT 6) 2 2 5. Intertrial variability of SOT scores. The range of score variability was noted for each patient. 6. Anteroposterior (AP) sway > 5°. Presence and number of sways > 5° were noted for each trial and each SOT. 7. Lateral sway > 1.25°. Presence and number of sways > 1.25° were noted for each trial and each SOT. 8. AP/lateral sway correlation—”circular sway.” This was defined as abnormal if a patient had abnormal sway in both the AP and lateral directions. 9. Falls on all 3 trials of an SOT. Additional information used in evaluating aphysiologic sway, but not included in the statistical analysis included the following. 1. Presence of severely abnormal composite scores and SOT patterns (especially abnormal score on SOT 1) in a patient who walks into the office without assistance. 2. Abnormal scores on SOTs 1 and 2 with normal Romberg testing. 3. Exaggerated and inconsistent motor responses to small platform translations.

In addition to the analysis of the above criteria, an experienced examiner who was unfamiliar with the clinical case made a subjective evaluation of the CDP results. The motor control test portion of CDP has been identified as a useful additional tool in evaluating nonphysiologic performance. This part of the test was used in our subjective evaluation, but it was not used for comparison between groups in our study because of the difficulty in quantifying this information. Each subject’s data were evaluated overall for nonorganic sway pattern by use of previously published criteria and clinical judgment. For example, if a patient had essentially normal scores throughout all SOTs except for a minimally abnormal score on SOT 1, overall the patient was judged to have an organic pattern. If, on the other hand, the patient had much poorer performance on SOT 1 than all subsequent SOTs with lateral sway noted, overall the patient was judged to have a nonorganic pattern. All data were recorded and coded into the SPSS 6.1 statistical program. An independent-samples t test was used to evaluate differences among continuous data between groups. A paired-samples t test was used to evaluate differences in posturography scores among individuals. The Pearson χ2 test was used to compare categorical data between groups, and the sign test was used to evaluate the distributions of 2 related (paired) categorical samples. A significance level of α = 0.05 was used to ascertain statistical significance for all tests. RESULTS

Group 1 consisted of 50 patients who had potential secondary gain as evidenced by a pending lawsuit, worker’s compensation claim, or disability claim. Group 2 contained 50 patients who had no identifiable

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Table 3. AP sway > 5° SOT

Group 1 (%)

Group 2 (%)

4 (P < 0.05, RR = 2.9) 5 (P < 0.05, RR = 3.72) 6 (P < 0.05, RR = 2.57)

42 54 42

20 24 22

79.5 ± 17.0 for SOT 2, and 75.0 ± 24.5 for SOT 3. In group 2, scores were 91.7 ± 4.6 for SOT 1, 87.0 ± 7.6 for SOT 2, and 85.5 ± 13.4 for SOT 3. Substandard performance on SOTs 1 and 2. Fig 3. Overall evaluation of CDP performance: Nonorganic versus organic sway patterns (P < 0.05).

source of secondary gain as described for the first group. The mean age for group 1 was 43.8 ± 12.4 years compared with 63.2 ± 15.7 years for group 2 (P < 0.0001). There was a male-to-female ratio of 1.5 in group 1 and 1.08 in group 2. This was not statistically significant, although there was a trend for more men in the secondary gain group. The initial clinical diagnoses are listed by group in Table 2. The most striking discrepancy is the higher number of “dizziness of unknown cause” diagnoses and the lower number of benign paroxysmal positional vertigo diagnoses in group 1. This was statistically significant (P < 0.05) for only these 2 diagnoses. Findings of the audiometric evaluations (Fig 1) were normal/symmetric in the majority of all patients in this study, but only 10% of group 1 had abnormal audiograms compared with 30% in group 2 (P < 0.05, relative risk [RR] = 3.86). ENG results (Fig 2) demonstrated significant differences in caloric and noncaloric testing between the 2 groups. In group 1, 60% had normal caloric test results compared with 24% in group 2 (P < 0.05, RR = 4.75), and noncaloric test results were normal in 72% of group 1 patients compared with only 22% in group 2 (P < 0.05, RR = 9.12). When audiometry and ENG are considered together, 50% of group 1 patients had normal findings on both tests compared with only 4% of group 1 patients (P < 0.0001). CDP Results Mean SOT performance. Mean composite scores were not significantly different (group 1, 58.2; group 2, 60.2). Individual SOT scores were not significantly different for SOTs 4, 5, and 6. However, SOTs 1, 2, and 3 demonstrated statistically significant (P < 0.05) lower scores for group 1 and much greater variability in scores. In group 1, scores were 88.4 ± 10.5 for SOT 1,

Group 1 was more likely to have abnormal scores on SOTs 1 and 2 (RR = 2.8, P < 0.05). Abnormal scores for SOT 1 were found in 38% of group 1 patients compared with only 18% of group 2 patients. Abnormal scores on SOT 2 were found in 40% of group 1 patients compared with only 18% of group 2 patients. Goebel formula for comparison of SOTs 1 and 2 and SOTs 5 and 6. Group 1 as a whole had higher

scores for SOTs 5 and 6 compared with SOTs 1 and 2 than did group 2. With the Goebel formula the average score for group 1 was 9.8 compared with 34.1 for group 2 (P < 0.05). Nearly half (48%) of group 1 patients had higher scores on SOTs 5 and 6 compared with about a third (34%) of group 2 patients with this formula. Formulaic comparison between scores on SOTs 1 and 2 and SOTs 5 and 6 (see criterion 4 above).

Group comparison of average scores demonstrated significantly (P < 0.05) lower scores (ie, better performance on SOTs 5 and 6 than SOTs 1 and 2) for group 1 (43.4) than group 2 (54.6). Half (50%) of all group 1 patients scored below 40, whereas only about one third (38%) of group 2 patients scored this low. Intertrial variability of SOT scores. Group 1 demonstrated 2-fold variability between individual trials on SOTs 1 and 2 compared with group 2. There was a mean variability of 9% (7.86 ± 15.2) for SOT 1 compared with 4% (3.62 ± 2.73) for group 2 (P = 0.055). For SOT 2, group 1 had a variability of 14% (11.26 ± 12.93) compared with 7.8% (6.76 ± 4.71) for group 2 (P < 0.05). There was no significant variability between groups for SOTs 3 to 6. AP sway > 5°. Group 1 demonstrated AP sways > 5° more than twice as often as group 2 for all SOTs. However, this was only statistically significant for SOTs 4, 5, and 6 (Table 3). Lateral sway > 1.25°. Group 1 demonstrated more lateral sway > 1.25° than group 2 for all SOTs. This was statistically significant only for SOTs 3, 4, 5, and 6, in which group 1 demonstrated > 2-fold incidence of lateral sway than group 2 (Table 4).

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Table 4. Lateral sway > 1.25°

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Table 5. Circular sway

SOT

Group 1 (%)

Group 2 (%)

SOT

Group 1 (%)

Group 2 (%)

3 (P < 0.05, RR = 3.46) 4 (P < 0.05, RR = 2.95) 5 (P < 0.05, RR = 4.69) 6 (P < 0.05, RR = 3.85)

32 36 54 52

12 16 20 22

4 (P < 0.05, RR = 2.17) 5 (P < 0.05, RR = 2.19) 6 (P < 0.05, RR = 2.28)

24 38 34

8 12 10

AP/Lateral sway correlation—”circular sway.”

Again, group 1 more frequently demonstrated circular sway for all SOTs than did group 2. This was statistically significant for SOTs 4, 5, and 6, where circular sway was present 3 times more often in group 1 than in group 2 (Table 5). Falls on all 3 trials of an SOT. Despite a much higher incidence of AP and lateral sway, group 1 was much less likely to demonstrate falls on SOTs 5 and 6. For SOT 5, only 10% of group 1 consistently fell compared with 30% in group 2 (P < 0.5, RR = 3.8). For SOT 6, 12% of group 1 patients consistently fell compared with 32% in group 2 (P < 0.05, RR = 3.5). Subjective evaluation of CDP performance by an experienced examiner resulted in the overall finding of nonorganic sway patterns almost exclusively in group 1. Group 1 demonstrated nonorganic sway patterns in 76% of patients compared with only 8% of patients in group 2 (P < 0.0001) (Fig 3). DISCUSSION

Diagnostic tests used to determine vestibular dysfunction have traditionally relied on evaluation of the horizontal vestibular-ocular reflex by ENG and rotational chair testing. Specifically, these tests, either singly or together, evaluate the reflex arc from the horizontal semicircular canal through the superior division of the vestibular nerve to the superior vestibular nucleus. The efferent limb goes through the oculomotor and abducens nerves for output to the medial and lateral rectus muscles, resulting in the measured nystagmus. These forms of testing, however, evaluate only a small portion of the vestibular system. For the most part, they do not evaluate input from the posterior and superior semicircular canals; the inferior division of the vestibular nerve; the medial, lateral, and inferior vestibular nuclei; outputs for the vertical vestibular-ocular reflex; or the vestibulospinal reflex. Information concerning overall balance function from ENG and rotational chair testing is also lacking. Information regarding the state of vestibular compensation can be gleaned from rotational chair testing and minimally from ENG testing, but neither contributes any information regarding the functional status of a patient. A normal evaluation with

ENG and rotational chair testing does not exclude the possibility of a vestibular lesion, nor does it identify a malingerer. Conversely, an abnormal ENG or rotational chair result does not exclude the possibility of exaggeration of symptoms/disability. CDP is helpful in evaluating the vestibulospinal reflex arc along with other components for balance. This is accomplished by objectively measuring postural sway under varying conditions of visual and somatosensory input. Results of individual tests are compared with age-matched normative data. CDP has been shown to be a reliable and valid test of postural stability5 and has been shown to identify balance dysfunction despite normal caloric test results.11 Nonorganic sway patterns seen on posturography are believed to be the result of anxiety, inability to follow test instructions, or outright malingering. Several studies have demonstrated the ability of posturography to identify nonorganic sway patterns. Uimomen et al6 studied the ability of static posturography to distinguish “simulated vertigo” from acute vertigo caused by vestibular neuritis. Although sway velocity and sway area were not able to distinguish pathologic from simulated vertigo, the Romberg quotient based on sway velocity could distinguish these groups. However, their study demonstrated no better identification of simulated vertigo with static posturography than observation by a trained clinician (sensitivity 77%, specificity 71%). Another study using static posturography by Guidetti8 reported successful identification of exaggerated sway by correlation of AP and lateral sway components. A greater degree of success in identifying nonorganic sway patterns has been found with CDP. Cevette et al,7 using CDP, were able to distinguish a group of 22 suspected malingerers from a group of normal age-matched controls and a group of patients with vestibular dysfunction. This distinction was made with 2 criteria: (1) overall better performance on SOTs 5 and 6 compared with SOTs 1 and 2; and (2) greater intertrial variability. Although a tendency for greater intertrial variability was noted among malingerers, this was not believed to be a useful criterion for distinguishing pathologic from aphysiologic sway patterns. However, 95.5% of the malingerers were accurately identified with the criterion

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of better performance on SOTs 5 and 6 compared with SOTs 1 and 2. This criterion was referred to as the hallmark of aphysiologic performance because it is physiologically inconsistent that a patient will perform relatively better on the most difficult trials (SOTs 5 and 6) than on the easiest trials (SOTs 1 and 2). Goebel et al9 studied different criteria in 3 groups of patients: healthy controls, patients with vestibular dysfunction, and healthy subjects instructed to feign imbalance. Three of their criteria were significantly different for the malingering group than for the normal and patient groups: (1) substandard performance on SOT 1 (sensitivity 72%, specificity 96%); (2) exaggerated motor responses to small platform translations (sensitivity 32%, specificity 95%); and (3) inconsistent responses to small and large platform translations (sensitivity 72%, specificity 95%). SOT 1 is the easiest of all tests to perform (standing on a fixed platform with eyes open and a stable visual reference). This should be performed with ease by virtually any patient who can walk into the room unsupported. Platform translations result in an immediate reflex response followed by stabilization of posture in the normal and pathologic conditions. Significant deviations suggest voluntary alterations in posture. Other criteria that Goebel et al9 found not to be useful in distinguishing aphysiologic sway patterns included better scores on SOTs 5 and 6 compared with SOTs 1 and 2. They believed this might have been related to the use of “best score” for each trial rather than the average score. Two other criteria not found to be useful were excessive AP (>7.5°) and lateral sway (>2.5°) without falls. It was believed that this likely would have been useful if the magnitude of acceptable sway would have been reduced. For this reason, we evaluated sway without falls > 5° for AP sway and > 1.25° of lateral sway in our study. To the best of our knowledge, no one has ever studied the prevalence of nonorganic sway patterns in a population of patients with secondary gain. Our group 1 patients all had incentive for poor performance on CDP because of pending litigation, worker’s compensation claims, or disability claims. The age of this secondary gain group was significantly younger than our patient group. There were 1.5 times more men than women in this group, although this was not statistically significant. This likely reflects the general characteristics of the litigious population and not the vestibular patient population. A characteristic indicator of the secondary gain group was their initial clinical impression. Thirty-seven (74%) of our secondary gain group defied clinical diag-

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nosis (ie, dizziness of unknown cause) on their initial office visit compared with only 32% of the patient group. Symptom magnification and contrived symptoms could be the result of the large number of patients whose disease cannot be classified at their initial office visit. Audiometric evaluation was 3 times more likely to be normal or symmetric in the secondary gain group than in the patient group. ENG results identified significant discrepancies between the 2 groups. The secondary gain group was much more likely to have normal caloric test results (60% vs 24%) and normal noncaloric test results (72% vs 22%) than the patient group. Taken together, audiometry and ENG test results were normal in 50% of our secondary gain group but in only 2 patients (4%) in the patient group. Our CDP data demonstrate significant differences between the 2 groups tested, although it should be noted that there was no significant difference in mean composite scores between the groups. Abnormal AP, lateral, and circular sway were found to be 2 to 3 times more common among the patients with secondary gain. This difference was only significant for the more difficult trials (SOTs 4-6). The reason this was not a significant finding in the easier trials is likely because of the relatively fewer episodes of significant sway in those trials. Circular sway was seen almost exclusively in the secondary gain group and seems to be a very distinct characteristic of this group. Despite the significantly greater amount of AP, lateral, and circular sway among the secondary gain group, they were significantly less likely to fall on SOTs 5 and 6 by approximately one third. Intertrial variability was only significantly greater for the secondary gain group for SOT 1s and 2. Variability for SOTs 3 to 6 was almost identical for both groups. This illustrates the reproducibility of performance on SOTs 1 and 2 among patients in group 2 despite vestibular pathology, whereas the more difficult trials resulted in greater variability for both groups. Additionally, substandard performance on SOTs 1 and 2 was more than twice as common among the secondary gain group. Normative data for SOT scores on the easier trials (SOTs 1 and 2) are higher than the scores on the more difficult trials (SOTs 5 and 6). Performance in relation to the normative data should be relatively equivalent for any given healthy individual. When there is a vestibular disorder, the relative performance on SOTs 5 and 6 will be decreased in relation to that on SOTs 1 and 2. The reverse situation, better performance on SOTs 5 and 6 compared with 1 and 2, is physiologically inconsistent. Although no individual in our study groups had absolute performance better on the more difficult trials,

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approximately half of our secondary gain group performed relatively better on SOTs 5 and 6 compared with 1 and 2 in relation to normative data. However, a third of our patient group also performed similarly. The large number from the patient group with better performance on the more difficult trials is likely an age-related anomaly. Because there is a significant age discrepancy between the 2 groups studied, the normative data used for comparison are also significantly different. Although the normative data for SOTs 1 and 2 drop 1% to 2% for the older group compared with the younger group, the mean normal scores for SOTs 5 and 6 change 7% and 12%, respectively. This artificially increases the relative performance on the more difficult trials for the older patients. It is also interesting to note the relatively better overall performance on CDP testing in our group 2 patients despite the significant age discrepancy. Of course, the true number of malingerers in our secondary gain group is not known. Depending on the criteria we use, the number of malingerers could be estimated to be as low as 40% and as high as 76%. By comparison, the patient group could contain as many as 34% malingerers or as few as 4%. Because there is no test criterion that is ideal, clinical judgment should be used in assessing the presence of nonorganic sway patterns on CDP. It is not uncommon to see a patient who barely falls into one of the categories of nonorganic sway but who otherwise presents a clearly organic or normal sway pattern. The converse situation is also seen—the patient who fulfills many but not all of the criteria for nonorganic sway. This is why we included a subjective overall evaluation of the CDP. With an experienced clinician, 76% of our secondary gain group, but only 8% of our patient group, was judged to have nonorganic sway patterns. Obviously, the 4 patients (8%) in the patient group could be malingering for reasons that were not apparent at the time of our study, or possibly this could represent anxiety or some other psychogenic cause. In summary, the profile of a prototypical patient reporting dizziness that has obvious secondary gain and is malingering would be described as follows: a 40year-old man with an initial impression of “dizziness of uncertain cause,” normal or symmetric hearing, and normal ENG results. CDP findings would include substandard performance on SOTs 1 and 2 with a great degree of intertrial variability, relatively better performance on SOTs 5 and 6 compared to SOTs 1 and 2, and circular sway (AP sway > 5° and lateral sway > 1.25°) without falling. Of course, not all patients exhibit all of these characteristics, but these characteristics should be kept in mind when evaluating for possible malingering.

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Additionally, it is not uncommon in the clinical setting to encounter patients who have organic pathologies and exaggerate their symptoms for monetary gain. Such patients would not be as easily identified with the prototype detailed above. Binder and Rohling12 performed a meta-analysis on the impact of financial incentives on disability, symptoms, and objective findings in patients with closed head injuries. They found that patients with the less severe injuries were more likely to seek monetary compensation. They estimated that elimination of monetary incentives would reduce the number of patients reporting neuropsychological problems by 23%. Schmand et al13 found that patients who had sustained whiplash were twice as likely to demonstrate cognitive underperformance on testing when litigation was pending than when no litigation was pending. In their study 61% of patients with pending litigation had a positive score on the malingering test compared with only 29% among patients with no pending lawsuits. This is comparable with the results of our study. However, neither of these previous studies separated out patients who had monetary incentive but no pending litigation (ie, worker’s compensation, disability claims, or nonlitigants seeking insurance settlements), which would result in a higher percentage of underperformance in the control group and a lower number of underperformers in the litigation groups. Our study likely has a larger discrepancy of nonorganic findings in our secondary gain group because of our differing method of classification. We suspect that malingering is more prevalent among the symptoms of dizziness and cognitive difficulties in patients with whiplash or closed-head injuries than in those with other disabilities in general because they are perceived to be easier symptoms to feign. The high prevalence of normal audiometric and ENG evaluations in the secondary gain group (50% vs 4%) is strong circumstantial evidence of no existing pathology, but it does not exclude vestibular pathology among these patients. When this information is considered in light of the high number of nonorganic sway patterns on CDP testing (76% vs 8%) in a patient population at risk for poor performance, it becomes rather obvious that the secondary gain group contains many individuals malingering or significantly exaggerating their symptoms. It should also be noted that, although they are in the minority, there are still a large number of individuals who have organic sway patterns (24%) in the secondary gain group. A high degree of suspicion for malingering or symptom magnification should be maintained when evaluating the patient who reports dizziness and has potential secondary gain. This study

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emphasizes the need for formal objective evaluation of such patients. 3.

CONCLUSIONS

First, in this study patients with obvious secondary gain compared with those who had no obvious secondary gain were statistically more likely to (1) be younger (43.8 vs 63.2), (2) have an initial clinical impression of dizziness of uncertain cause (74% vs 32%), (3) have normal audiometry and ENG testing (50% vs 4%), and (4) have nonorganic sway patterns on CDP (76% vs 8%). Second, patients in this study with obvious secondary gain more frequently demonstrated CDP findings of (1) significant AP and lateral sway without falls on SOTs 4 to 6, (2) a circular sway pattern, and (3) poorer performance on SOTs 1 to 3 with greater intertrial variability. Third, a high degree of suspicion should be maintained when evaluating a patient reporting dizziness who has obvious potential for secondary gain—a pending lawsuit, worker’s compensation, or disability claim. Our study suggests a very high incidence of symptom magnification or outright malingering in this group of patients.

4.

5. 6. 7. 8. 9.

10. 11. 12.

REFERENCES 1. Gorman WF. Defining malingering. J Forensic Sci 1982;27:4017. 2. McLemore T, Delozier J. 1985 National ambulatory medical care survey. In: National Center for Health Statistics (Hyattsville,

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MD). Advance data from vital and health statistics. No. 128. Government Printing Office, Washington (DC); 1987. DHHS Publication No. (PHS) 87-1250. Kroenke K, Mangelsdorff D. Common symptoms in ambulatory care: incidence, evaluation, therapy, and outcome. Am J Med 1989;86:262-5. Koch H, Smith MC. Office-based ambulatory care for patients 75 years old and over. National Ambulatory Medical Care Survey 1980 and 1981. In: National Center for Health Statistics (Hyattsville, MD): Advance data from vital and health statistics. No. 110. Government Printing Office, Washington (DC); 1985. DHHS Publication No. (PHS) 85-1250. Monsell EM, Furman JM, Herdman SJ, et al. Computerized dynamic platform posturography. Otolaryngol Head Neck Surg 1997;117:394-8. Uimonen S, Laitakari K, Kiukaanniemi H, et al. Does posturography differentiate malingerers from vertiginous patients? J Vestib Res 1995;5:117-24. Cevette MJ, Puetz B, Marion MS, et al. Aphysiologic performance on dynamic posturography. Otolaryngol Head Neck Surg 1995;112:676-88. Guidetti G. Valuatizione medico-legale dei disturbi posturali. In: Cesarani A, Alpini D, editors. Aspetti medico-legali dei disturbi dell’equilirio. Milan, Italy: Bi & Gi Editori; 1991. p. 163-78. Goebel JA, Sataloff RT, Hanson JM, et al. Posturographic evidence of nonorganic sway patterns in normal subjects, patients, and suspected malingerers. Otolaryngol Head Neck Surg 1997; 117:293-302. Nashner LM. Computerized dynamic posturography. In: Jacobsen GP, Newman CW, Kartush JM, editors. Handbook of balance function testing. St Louis: Mosby 1993. p. 280-307. Goebel JA, Paige GD. Dynamic posturography and caloric test results in patients with and without vertigo. Otolaryngol Head Neck Surg 1989;100:553-8. Binder LM, Rohling ML. Money matters: a meta-analytic review of the effects of financial incentives on recovery after closedhead injury. Am J Psychiatry 1996;153:7-10. Schmand B, Lindeboom J, Schagen S, et al. Cognitive complaints in patients after whiplash injury: the impact of malingering. J Neurol Neurosurg Psychiatry 1998;64:339-43.

American Laryngological Association Annual Meeting

This meeting will be held as part of the Combined Otolaryngological Spring Meetings (COSM) May 13-14, 2000, in Orlando, FL, at the Marriott Orlando World Center. For further information, contact the Office of the Secretary, Robert H. Ossoff, DMD, MD, Department of Otolaryngology, Vanderbilt University Medical Center, S2100 MCN, Nashville, TN 37232-2559; phone, 615-322-7267; fax, 615-343-7604.