Detecting feigned cognitive impairment using pupillometry on the Warrington Recognition Memory Test for Words.

OBJECTIVE: Pupillometry provides information about physiological and psychological processes related to cognitive load, familiarity, and deception, and it is outside of conscious control. This study examined pupillary dilation patterns during a performance validity test (PVT) among adults with true and feigned impairment of traumatic brain injury (TBI). PARTICIPANTS AND METHODS: Participants were 214 adults in three groups: adults with bona fide moderate to severe TBI (TBI; n = 51), healthy comparisons instructed to perform their best (HC; n = 72), and healthy adults instructed and incentivized to simulate cognitive impairment due to TBI (SIM; n = 91). The Recognition Memory Test (RMT) was administered in the context of a comprehensive neuropsychological battery. Three pupillary indices were evaluated. Two pure pupil dilation (PD) indices assessed a simple measure of baseline arousal (PD-Baseline) and a nuanced measure of dynamic engagement (PD-Range). A pupillary-behavioral index was also evaluated. Dilation-response inconsistency (DRI) captured the frequency with which examinees displayed a pupillary familiarity response to the correct answer but selected the unfamiliar stimulus (incorrect answer). RESULTS: All three indices differed significantly among the groups, with medium-to-large effect sizes. PD-Baseline appeared sensitive to oculomotor dysfunction due to TBI; adults with TBI displayed significantly lower chronic arousal as compared to the two groups of healthy adults (SIM, HC). Dynamic engagement (PD-Range) yielded a hierarchical structure such that SIM were more dynamically engaged than TBI followed by HC. As predicted, simulators engaged in DRI significantly more frequently than other groups. Moreover, subgroup analyses indicated that DRI differed significantly for simulators who scored in the invalid range on the RMT (n = 45) versus adults with genuine TBI who scored invalidly (n = 15). CONCLUSIONS: The findings support continued research on the application of pupillometry to performance validity assessment: Overall, the findings highlight the promise of biometric indices in multimethod assessments of performance validity.

Verbal fluency and digit span variables as performance validity indicators in experimentally induced malingering and real world patients with TBI.

Objective: This study was designed to examine the classification accuracy of verbal fluency (VF) measures as performance validity tests (PVT).Method: Student volunteers were assigned to the control (n = 57) or experimental malingering (n = 24) condition. An archival sample of 77 patients with TBI served as a clinical comparison.Results: Among students, FAS T-score ≤29 produced a good combination of sensitivity (.40-.42) and specificity (.89-.95). Animals T-score ≤31 had superior sensitivity (.53-.71) at .86-.93 specificity. VF tests performed similarly to commonly used PVTs embedded within Digit Span: RDS ≤7 (.54-.80 sensitivity at .93-.97 specificity) and age-corrected scaled score (ACSS) ≤6 (.54-.67 sensitivity at .94-.96 specificity). In the clinical sample, specificity was lower at liberal cutoffs [animals T-score ≤31 (.89-.91), RDS ≤7 (.86-.89) and ACSS ≤6 (.86-.96)], but comparable at conservative cutoffs [animals T-score ≤29 (.94-.96), RDS ≤6 (.95-.98) and ACSS ≤5 (.92-.96)].Conclusions: Among students, VF measures had higher signal detection performance than previously reported in clinical samples, likely due to the absence of genuine impairment. The superior classification accuracy of animal relative to letter fluency was replicated. Results suggest that existing validity cutoffs can be extended to cognitively high functioning examinees, and emphasize the importance of population-specific cutoffs.

Psychological Symptoms and Rates of Performance Validity Improve Following Trauma-Focused Treatment in Veterans with PTSD and History of Mild-to-Moderate TBI.

OBJECTIVE: Iraq and Afghanistan Veterans with posttraumatic stress disorder (PTSD) and traumatic brain injury (TBI) history have high rates of performance validity test (PVT) failure. The study aimed to determine whether those with scores in the invalid versus valid range on PVTs show similar benefit from psychotherapy and if psychotherapy improves PVT performance. METHOD: Veterans (N = 100) with PTSD, mild-to-moderate TBI history, and cognitive complaints underwent neuropsychological testing at baseline, post-treatment, and 3-month post-treatment. Veterans were randomly assigned to cognitive processing therapy (CPT) or a novel hybrid intervention integrating CPT with TBI psychoeducation and cognitive rehabilitation strategies from Cognitive Symptom Management and Rehabilitation Therapy (CogSMART). Performance below standard cutoffs on any PVT trial across three different PVT measures was considered invalid (PVT-Fail), whereas performance above cutoffs on all measures was considered valid (PVT-Pass). RESULTS: Although both PVT groups exhibited clinically significant improvement in PTSD symptoms, the PVT-Pass group demonstrated greater symptom reduction than the PVT-Fail group. Measures of post-concussive and depressive symptoms improved to a similar degree across groups. Treatment condition did not moderate these results. Rate of valid test performance increased from baseline to follow-up across conditions, with a stronger effect in the SMART-CPT compared to CPT condition. CONCLUSION: Both PVT groups experienced improved psychological symptoms following treatment. Veterans who failed PVTs at baseline demonstrated better test engagement following treatment, resulting in higher rates of valid PVTs at follow-up. Veterans with invalid PVTs should be enrolled in trauma-focused treatment and may benefit from neuropsychological assessment after, rather than before, treatment.

Health histories and medical evaluations of patients with complaints of chemosensory dysfunction.

Key elements for understanding, assessing, and treating a patient with a complaint of chemosensory dysfunction include establishing a relevant medical history and performing a focused medical examination. This age-old medical approach combines the utilization of associated tests and the results of chemosensory testing to establish a diagnosis and plan for medical management. Chemosensory testing is critical to establish the degree of dysfunction, the veracity and accuracy of a patient's self-report, the efficacy of treatments, and the degree to which spontaneous recovery occurs. In common with most medical disorders, it is incumbent upon the physician to determine, as best as possible, the time of onset of the symptom, its severity, precipitating factors, comorbidities, and fluctuations over time to understand the underlying pathophysiology. Importantly, distinguishing between "taste" loss due to decreased flavor sensations secondary to olfactory system compromise and "taste" loss due to true taste bud-mediated sensory alterations is critical. Unfortunately, this distinction is often underappreciated by medical professionals and laypersons alike, resulting in needless referrals within the medical community, including those related to imaging and gastroenterological testing. This chapter outlines the basic elements of the medical history and assessment of patients with complaints of chemosensory dysfunction, including a discussion on how to detect malingering.

Assessing susceptibility of a temporal discounting task to faking.

OBJECTIVE: Temporal discounting describes the devaluation of delayed rewards. Because temporal discounting is predictive of substance misuse, its clinical assessment could improve prevention (e.g., identifying at-risk youth) and treatment (e.g., predicting relapse). However, if discounting rates can be faked (e.g., to avoid treatment), their clinical utility may be limited. For the first time, we measured the influence of deception in a temporal discounting task. METHOD: We recruited 200 participants (44% female, Mage= 33) through Amazon Mechanical Turk. Participants completed a discounting assessment with instructions to (a) respond honestly, (b) fake good (i.e., simulate better versions of themselves), or (c) fake bad. RESULTS: Generalized linear mixed effects analysis showed that in Experiment 1, nonclinical samples faked good ( Mhyperbolic discounting rate= 0.002) or bad ( M= 0.086) compared to the Honest group ( M= 0.008). In Experiment 2, cigarette smokers faked good ( M= 0.003) compared to the Honest group ( M= 0.025). CONCLUSIONS: Temporal discounting transects the disciplines of psychology, biology, and behavioral economics. Before its promise as an endophenotype can be realized, assessments must be translated for clinical use. Opaquer temporal discounting tasks, or secondary measures of lying, may be required before temporal discounting can be confidently extended to clinical settings.

Eliciting Response Bias Within Forced Choice Tests to Detect Random Responders.

The Forced Choice Test (FCT) can be used to detect malingered loss of memory or sensory deficits. In this test, examinees are presented with two stimuli, one correct and one incorrect, in regards to a specific event or a perceptual discrimination task. The task is to select the correct answer alternative, or guess if it is unknown. Genuine impairment is associated with test scores that fall within chance performance. In contrast, malingered impairment is associated with purposeful avoidance of correct information, resulting in below chance performance. However, a substantial proportion of malingerers intentionally randomize their responses, and are missed by the test. Here we examine whether a 'runs test' and a 'within test response 'bias' have diagnostic value to detect this intentional randomization. We instructed 73 examinees to malinger red/green blindness and subjected them to a FCT. For half of the examinees we manipulated the ambiguity between answer alternatives over the test trials in order to elicit a response bias. Compared to a sample of 10,000 cases of computer generated genuine performance, the runs test and response bias both detected malingered performance better than chance.

The Honest Palm Sign: Detecting Incomplete Effort on Physical Examination.

BACKGROUND: We investigated a simple, novel diagnostic test for detecting incomplete effort during the motor portion of the neurological examination. METHODS: The results from the honest palm sign (HPS) were evaluated for 162 consecutive neuro-oncology patients who had undergone upper extremity strength testing. Deltoid, bicep, and wrist extensor strength was assessed in all patients. During the examination, patients were repeatedly encouraged to "try as hard as possible" and to "resist with all your strength." The absence of nail prints on the palms constituted a positive HPS test result (i.e., indicative of incomplete effort). The presence of nail prints constituted a negative HPS test result (i.e., indicative of full effort). RESULTS: A total of 162 patients were tested. Their mean age was 55.5 ± 14.9 years, the median Karnofsky performance scale score was 80 (range, 60-100), and 63 patients (39%) were men. Of the 162 patients, 102 (63%) had malignant gliomas, 28 (17%) had brain metastases, 21 (13%) had other primary brain tumors, and 11 (6.8%) had primary central nervous system lymphomas. Of the 162 patients, 48 (30%) had positive HPS test results. The test sensitivity (84.6%), specificity (75.2%), positive likelihood ratio (3.41), and negative likelihood ratio (0.205) were good. After excluding 33 patients with characteristics that rendered them unsuitable for testing, the results from the remaining 129 patients were analyzed. The sensitivity was unchanged (84.6%), but the specificity (96.6%), positive likelihood ratio (24.5), and negative likelihood ratio (0.16) improved dramatically. CONCLUSIONS: The HPS test is a simple, sensitive, and very specific test for detecting incomplete effort during the motor portion of neurological evaluations.

Illness Perceptions Predict Cognitive Performance Validity.

OBJECTIVES: The aim of this study was to investigate the relationship of psychological variables to cognitive performance validity test (PVT) results in mixed forensic and nonforensic clinical samples. METHODS: Participants included 183 adults who underwent comprehensive neuropsychological examination. Criterion groups were formed, that is, Credible Group or Noncredible Group, based upon their performance on the Word Memory Test and other stand-alone and embedded PVT measures. RESULTS: Multivariate logistic regression analysis identified three significant predictors of cognitive performance validity. These included two psychological constructs, for example, Cogniphobia (perception that cognitive effort will exacerbate neurological symptoms), and Symptom Identity (perception that current symptoms are the result of illness or injury), and one contextual factor (forensic). While there was no interaction between these factors, elevated scores were most often observed in the forensic sample, suggesting that these independently contributing intrinsic psychological factors are more likely to occur in a forensic environment. CONCLUSIONS: Illness perceptions were significant predictors of cognitive performance validity particularly when they reached very elevated levels. Extreme elevations were more common among participants in the forensic sample, and potential reasons for this pattern are explored. (JINS, 2018, 24, 735-745).

Detecting Symptom Exaggeration in College Students Seeking ADHD Treatment: Performance Validity Assessment Using the NV-MSVT and IVA-Plus.

The symptoms of ADHD are highly subjective, and there is ample empirical evidence that demonstrates the ease with which impairments in attention can be feigned on many commonly used subjective and objective measures of attention. We examined the combination of two assessment measures, NV-MSVT and IVA+, to screen for performance validity and ADHD symptoms in college students. Results indicated that the NV-MSVT was effective in differentiating between students with potential high impairment, such as ADHD, and possible malingerers. In addition, in vivo clinical data (N = 350) resulted in lower validity cut-off scores on the IVA+ than had been previously suggested. Clinical implications and future research are also discussed.

Grip strength feigning is hard to detect: an exploratory study.

Detecting submaximal effort when testing grip strength is difficult. Research so far has focused on the discrimination between sincere and feigning healthy participants, whereas the clinically relevant distinction is between injured patients and feigning participants. The aim of our study was to compare rapid exchange grip and isometric grip strength testing in 41 participants feigning weakness with 39 patients with decreased hand function. Various parameters that describe grip strength were recorded and tested for differences between the groups. Only the maximum grip strength during rapid exchange grip was found to be significantly higher in feigning participants compared with patients, but this cannot be used for decision-making on an individual basis. We found no parameters that are useful for the detection of feigned weakness in an individual case. LEVEL OF EVIDENCE: III.

Conversion, Factitious Disorder and Malingering: A Distinct Pattern or a Continuum?

This chapter is aimed at highlighting the recent findings concerning physiopathology, diagnosis, and management of conversion, factitious disorder, and malingering. Conversion disorder is the unintentional production of neurological symptom, whereas malingering and factitious disorder represent the voluntary production of symptoms with internal or external incentives. They have a close history and this has been frequently confounded. Practitioners are often confronted to medically unexplained symptoms; they represent almost 30% of neurologist's consultation. The first challenge is to detect them, and recent studies have confirmed the importance of "positive" clinical bedside signs based on incoherence and discordance, such as the Hoover's sign for the diagnosis of conversion disorder. Functional neuroimaging has allowed a better understanding of the pathophysiology, and highlighted abnormal cerebral activation patterns in conversion disorder in relation to motor, emotional, and limbic networks, different from feigners. This supports the theory evoked by Charcot of a "psychodynamic lesion," which is also reflected by the new term introduced in the DSM-5: functional neurological disorder. Multidisciplinary therapy is recommended with behavioral cognitive therapy, antidepressant to treat frequent comorbid anxiety or depression, and physiotherapy. Factitious disorder and malingering should be clearly delineated from conversion disorder. Factitious disorder should be considered as a mental illness and more research on its physiopathology and treatment is needed, when malingering is a non-medical condition encountered in medico-legal cases.

The Dancing Manias: Psychogenic Illness as a Social Phenomenon.

The dancing mania erupted in the 14th century in the wake of the Black Death, and recurred for centuries in central Europe - particularly Germany, the Netherlands, and Belgium - finally abating in the early 17th century. The term "dancing mania" was derived from "choreomania," a concatenation of choros (dance) and mania (madness). A variant, tarantism, was prevalent in southern Italy from the 15th to the 17th centuries, and was attributed at the time to bites from the tarantula spider. Affected individuals participated in continuous, prolonged, erratic, often frenzied and sometimes erotic, dancing. In the 14th century, the dancing mania was linked to a corruption of the festival of St. John's Day by ancient pagan customs, but by the 16th century it was commonly considered an ordeal sent by a saint, or a punishment from God for people's sins. Consequently, during outbreaks in the 14th and 15th centuries, the dancing mania was considered an issue for magistrates and priests, not physicians, even though the disorder proved intractable to decrees and exorcisms. However, in the 16th century Paracelsus discounted the idea that the saints caused or interceded in the cure of the dancing mania; he instead suggested a psychogenic or malingered etiology, and this reformulation brought the dancing mania within the purview of physicians. Paracelsus advocated various mystical, psychological, and pharmacological approaches, depending on the presumptive etiologic factors with individual patients. Only music provided any relief for tarantism. Later authors suggested that the dancing mania was a mass stress-induced psychosis, a mass psychogenic illness, a culturally determined form of ritualized behavior, a manifestation of religious ecstasy, or even the result of food poisoning caused by the toxic and psychoactive chemical products of ergot fungi. In reality, dancing manias did not have a single cause, but component causes likely included psychogenic illness, malingering, and ritualized behaviors.

Relationship of Reaction Time to Perception of a Stimulus and Volitionally Delayed Response.

BACKGROUND AND OBJECTIVE: Initiation of response in a simple reaction time (RT) task may precede conscious perception of the stimulus. Since volitionally delayed responses may require conscious perception of the stimulus before response initiation, it has been hypothesized that volitionally delayed responses will markedly delay RT. METHODS: We conducted two experiments with separate groups of healthy volunteers (n=16; n=13) who performed computerized simple and choice RT tasks. In the standard condition, we instructed the participants to respond to a visual stimulus by pushing a button as quickly as possible. In the second condition, we instructed the participants to respond after a slight volitional delay. The second experiment had an additional volitional delay condition in which we asked participants to delay their responses by an estimated 50% above their usual standard response. RESULTS: We found marked delays and increased variability when participants volitionally delayed their responses, averaging 322 ms for standard and 861 ms for delayed simple RTs (267% increase), and 650 ms for standard and 1018 ms for delayed choice RTs (157% increase). Effects did not differ across age, sex, or handedness. However, a minority of participants did not meaningfully delay their RT during the volitional delay conditions. CONCLUSIONS: On average, participants had marked delays when they tried to delay their responses slightly, but a subset of participants exhibited essentially no delay despite trying to delay. We suggest some potential mechanisms that future investigations might delineate.

A method for identifying color vision deficiency malingering.

PURPOSE: To propose a new test to identify color vision deficiency malingering. METHODS: An online survey was distributed to 130 truly color vision deficient participants and 160 participants willing to simulate color vision deficiency. The survey contained three sets of six color-adjusted versions of the standard Ishihara color plates each, as well as one set of six control plates. The plates that best discriminated both participant groups were selected for a "balanced" test emphasizing both sensitivity and specificity. A "specific" test that prioritized high specificity was also created by selecting from these plates. Statistical measures of the test (sensitivity, specificity, and Youden index) were assessed at each possible cut-off threshold, and a receiver operating characteristic (ROC) function with its area under the curve (AUC) charted. RESULTS: The redshift plate set was identified as having the highest difference of means between groups (-58%, CI: -64 to -52%), as well as the widest gap between group modes. Statistical measures of the "balanced" test show an optimal cut-off of at least two incorrectly identified plates to suggest malingering (Youden index: 0.773, sensitivity: 83.3%, specificity: 94.0%, AUC of ROC 0.918). The "specific" test was able to identify color vision deficiency simulators with a specificity of 100% when using a cut-off of at least two incorrectly identified plates (Youden index 0.599, sensitivity 59.9%, specificity 100%, AUC of ROC 0.881). CONCLUSIONS: Our proposed test for identifying color vision deficiency malingering demonstrates a high degree of reliability with AUCs of 0.918 and 0.881 for the "balanced" and "specific" tests, respectively. A cut-off threshold of at least two missed plates on the "specific" test was able to identify color vision deficiency simulators with 100% specificity.

Religious stigmata as malingering artifact: Report of a case and review of the literature.

RATIONALE: Artifacts or simulated diseases are self-inflicted conditions caused by various means and for different purposes. Disease simulation can be motivated, among other things, by illegal purposes, to escape from civil duties or prison sentences, for example, or to exploit specific situations in order to receive a range of benefits. In such cases, the simulator is fully aware of his or her actions and intentions. DIAGNOSES, INTERVENTIONS AND OUTCOMES: We report the case of a 42-year-old woman who, for 3 consecutive years, showed religious stigmata on the forehead and on the dorsal surface of hands and feet immediately before Easter. Lesions showed an acute onset, manifested as erosions and ulcerations, and healed a few days after Easter. Stigmata were immediately made public and every year faithful and curious people went in procession to the house of the patient, offering different kinds of gifts. After intervention of the police authority in the early days of the third episode, the patient and her family repented of their actions. Cutaneous lesions healed in few days and similar events did not occur during the following 2 years. LESSONS: Regardless of personal beliefs, the possibility that stigmata could be self-inflicted for illegal or profit purposes should always be considered.

Computerized Analysis of Verbal Fluency: Normative Data and the Effects of Repeated Testing, Simulated Malingering, and Traumatic Brain Injury.

In verbal fluency (VF) tests, subjects articulate words in a specified category during a short test period (typically 60 s). Verbal fluency tests are widely used to study language development and to evaluate memory retrieval in neuropsychiatric disorders. Performance is usually measured as the total number of correct words retrieved. Here, we describe the properties of a computerized VF (C-VF) test that tallies correct words and repetitions while providing additional lexical measures of word frequency, syllable count, and typicality. In addition, the C-VF permits (1) the analysis of the rate of responding over time, and (2) the analysis of the semantic relationships between words using a new method, Explicit Semantic Analysis (ESA), as well as the established semantic clustering and switching measures developed by Troyer et al. (1997). In Experiment 1, we gathered normative data from 180 subjects ranging in age from 18 to 82 years in semantic ("animals") and phonemic (letter "F") conditions. The number of words retrieved in 90 s correlated with education and daily hours of computer-use. The rate of word production declined sharply over time during both tests. In semantic conditions, correct-word scores correlated strongly with the number of ESA and Troyer-defined semantic switches as well as with an ESA-defined semantic organization index (SOI). In phonemic conditions, ESA revealed significant semantic influences in the sequence of words retrieved. In Experiment 2, we examined the test-retest reliability of different measures across three weekly tests in 40 young subjects. Different categories were used for each semantic ("animals", "parts of the body", and "foods") and phonemic (letters "F", "A", and "S") condition. After regressing out the influences of education and computer-use, we found that correct-word z-scores in the first session did not differ from those of the subjects in Experiment 1. Word production was uniformly greater in semantic than phonemic conditions. Intraclass correlation coefficients (ICCs) of correct-word z-scores were higher for phonemic (0.91) than semantic (0.77) tests. In semantic conditions, good reliability was also seen for the SOI (ICC = 0.68) and ESA-defined switches in semantic categories (ICC = 0.62). In Experiment 3, we examined the performance of subjects from Experiment 2 when instructed to malinger: 38% showed abnormal (p< 0.05) performance in semantic conditions. Simulated malingerers with abnormal scores could be distinguished with 80% sensitivity and 89% specificity from subjects with abnormal scores in Experiment 1 using lexical, temporal, and semantic measures. In Experiment 4, we tested patients with mild and severe traumatic brain injury (mTBI and sTBI). Patients with mTBI performed within the normal range, while patients with sTBI showed significant impairments in correct-word z-scores and category shifts. The lexical, temporal, and semantic measures of the C-VF provide an automated and comprehensive description of verbal fluency performance.

Pattern-reversal visual evoked potentials as a diagnostic tool for ocular malingering.

PURPOSE:: To investigate the contributions of transient pattern-reversal visual evoked potentials in the diagnosis of ocular malingering at a Brazilian university hospital. METHODS:: Adult patients with suspected malingering in one or both eyes were referred for visual evoked potential testing. Data from patients' medical records were reviewed and analyzed retrospectively. Data analysis included the distance optotype visual acuity based on a ETDRS retro-illuminated chart and the transient pattern-reversal visual evoked potential parameters of latency (milliseconds) and amplitude (microvolts) for the P100 component, using checkerboards with visual subtenses of 15' and 60'. Motivations for malingering were noted. RESULTS:: The 20 subjects included 11 (55%) women. Patient ages ranged from 21 to 61 years (mean= 45.05 ± 11.76 years; median= 49 years). In 8 patients (6 women), both eyes exhibited reduced visual acuity with normal pattern-reversal visually evoked potential parameters (pure malingerers). The remaining 12 patients (7 men) exhibited reduced vision in only 1 eye, with simulated reduced vision in the contralateral eye (exaggerators). Financial motivation was noted in 18 patients (9 men). CONCLUSION:: Normal pattern-reversal visually evoked potential parameters with suspected ocular malingering were observed in a 20 patient cohort. This electrophysiological technique appeared to be useful as a measure of visual pathway integrity in this specific population.

Pattern-reversal visual evoked potentials as a diagnostic tool for ocular malingering / Potenciais visuais evocados por padrões reversos como uma ferramenta diagnóstica de simulação

ABSTRACT Purpose: To investigate the contributions of transient pattern-reversal visual evoked potentials in the diagnosis of ocular malingering at a Brazilian university hospital. Methods: Adult patients with suspected malingering in one or both eyes were referred for visual evoked potential testing. Data from patients' medical records were reviewed and analyzed retrospectively. Data analysis included the distance optotype visual acuity based on a ETDRS retro-illuminated chart and the transient pattern-reversal visual evoked potential parameters of latency (milliseconds) and amplitude (microvolts) for the P100 component, using checkerboards with visual subtenses of 15' and 60'. Motivations for malingering were noted. Results: The 20 subjects included 11 (55%) women. Patient ages ranged from 21 to 61 years (mean= 45.05 ± 11.76 years; median= 49 years). In 8 patients (6 women), both eyes exhibited reduced visual acuity with normal pattern-reversal visually evoked potential parameters (pure malingerers). The remaining 12 patients (7 men) exhibited reduced vision in only 1 eye, with simulated reduced vision in the contralateral eye (exaggerators). Financial motivation was noted in 18 patients (9 men). Conclusion: Normal pattern-reversal visually evoked potential parameters with suspected ocular malingering were observed in a 20 patient cohort. This electrophysiological technique appeared to be useful as a measure of visual pathway integrity in this specific population.

RESUMO Objetivo: Investigar a contribuição dos potenciais visuais evocados por padrões reversos no diagnóstico de simulação de baixa de visão em um hospital universitário do Brasil. Métodos: Um grupo de pacientes adultos com suspeita de simulação de baixa de visão em um ou ambos os olhos foi avaliado e os dados analisados retrospectivamente. Foram medidos: acuidade visual de optotipos informada para longe utilizando a tabela ETDRS, parâmetros dos potenciais visuais evocados por padrões reversos de latência (milissegundos) e amplitude (microvolts) para o componente P100 com estímulos de ângulos visuais de 15' e 60'. A motivação do paciente para a simulação foi anotada. Resultados: Os participantes foram 20 indivíduos com 11 (55%) do sexo feminino. A idade variou de 21 a 61 anos (média= 45,05 ± 11,76 anos; mediana= 49 anos). Em 8 pacientes (6 mulheres) ambos os olhos tinham acuidade visual reduzida com parâmetros dos potenciais visuais evocados por padrão reverso normais para ambos os olhos (simuladores puros). Uma subsérie separada de 12 pacientes (7 homens) tinha visão reduzida em apenas um olho e estavam simulando redução da visão no outro olho (exacerbadores). A motivação financeira foi observada em 18 pacientes (9 homens). Conclusões: Parâmetros dos potenciais visuais evocados por padrões reversos normais foram encontrados neste grupo de 20 pacientes com suspeita de simulação. Esta técnica eletrofisiológica pode ser útil como uma medida da integridade do sistema visual nesta população de doentes.

Pattern visual evoked potentials for identifying malingering.

PURPOSE: To investigate the efficacy of pattern visual evoked potentials (VEPs) in evaluating objective visual acuity (VA) and discriminating malingerers. METHODS: Two hundred and forty-nine eyes of 249 patients aged 20-65 years were included. There were 147 eyes with macular diseases (group 1) and 102 eyes with optic nerve diseases (group 2). Amplitudes and latencies were analyzed and correlated with best-corrected visual acuity by a regression analysis. We found the best-correlated mode of pattern VEP, determined the relations, and then calculated the pattern VEP-estimated VA (PVEP-VA) of all 249 eyes, another 30 malingering eyes, 13 eyes with macular diseases, and 17 eyes with optic nerve diseases, and used a receiver operating characteristic (ROC) curve to determine a cutoff for acceptable variance between PVEP-VA and subjective VA to discriminate malingerers. RESULTS: The best correlation was between the amplitude of 50' checkerboard size (Amp50') and VA in every group. Significant correlation was between Amp50' and VA, where p < 0.0001 in group 1 and p = 0.020 in group 2. A logarithmic curve best fitted the correlation in the regression analysis, where y = 1.731 - 1.569x (R(2) = 0.611, p < 0.0001) in group 1 and y = 2.413 - 2.169x (R(2) = 0.531, p < 0.0001) in group 2 [x: log(Amp50'), y: PVEP-VA (logMAR)]. By using the relations and ROC curve, we determined a variance value of 0.4041 (logMAR) with 100% sensitivity and 94.0% specificity in group 1 and 0.3658 with 70.6% sensitivity and 50.5% specificity in group 2 to discriminate malingerers. CONCLUSIONS: The pattern VEP amplitude of 50' checkerboard size was useful to assess VA and can be helpful in discriminating malingering from real disability.