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Effort testing in patients with neurological symptoms unexplained by disease
Journal of Psychosomatic Research 65 (2008) 327 – 328
Commentary
Effort testing in patients with neurological symptoms unexplained by disease Jon Stone⁎ Department Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, UK Received 2 May 2008; received in revised form 6 May 2008; accepted 6 May 2008
When most people think about patients with neurological symptoms unexplained by disease (e.g., conversion symptoms such as paralysis or blackouts), one of several predictable themes usually emerge. Since the symptoms presented relate to a problem with the voluntary action of the nervous system, to what extent could these patients' symptoms be voluntarily or consciously manufactured? Can a disorder of voluntary action really be involuntary? Such questions do not hang so heavily over other symptoms unexplained by disease such as irritable bowel syndrome or chronic pain. This question has rarely been approached experimentally. Charcot [1] claimed to demonstrate the difference between hysterical catalepsy (sustained limb posturing) and malingered catalepsy with the use of tremor recordings. He thought the issue of simulation in ‘hysteria’ was ‘only a bugbear, before which the fearful and novice alone are stopped’. More recently, small studies have shown how poor doctors are at distinguishing ‘psychogenic’ or ‘hypnotic’ conversion symptoms from consciously simulated symptoms [2,3]. Some functional imaging [3–5], neurophysiological [6], and neuropsychological studies [7] have shown differences between simulated symptoms and conversion symptoms but with no consistent answers. At the bedside, all of the ‘positive’ physical signs of conversion symptoms also occur in
⁎ Department Clinical Neurosciences, Western General Hospital, Edinburgh EH4 2XU, UK. Tel.: +44 131 537 1167; fax: +44 0131 537 1132. E-mail address: [email protected]. 0022-3999/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2008.05.004
factitious states [8]. Hence, authors past and present have therefore placed weight on the detection of major inconsistencies in the history, a confession or marked discrepancies on covert surveillance to diagnose factitious neurological symptoms or malingering [9]. However, because these factors are unlikely to apply in everyday practice, the question of poor effort, exaggeration, or simulation usually remains. The study by Kemp et al. [10] in this issue of the journal—‘The base rate of effort test failure in patients with medically unexplained symptoms’—is therefore an especially welcome contribution to this area. Effort tests have been in routine use for many years. They are cognitive tests that are easier than they appear, so that even someone with severe cognitive impairment should be able to pass or score above chance. Three recent studies have found similar rates of effort test failure between patients with nonepileptic attacks and patients with epilepsy [11–13], whilst one did not [14]. However, this is the first study to compare a clinical population with conversion symptoms against subjects instructed to ‘malinger’. Patients with neurological symptoms unexplained by disease have high rates of cognitive symptoms even when this is not their main complaint (as evidenced by the figure of 71% of patients in this study). If part of the reason for weakness or other symptoms in these patients is a lack of effort, then it seems reasonable to assume that this might be reflected in a poor score on cognitive effort testing as well. It may come as a surprise (and a challenge) to some that Kemp et al. found a failure rate of only 11% in a sample of 43 of these patients, in contrast to 90% in a group of subjects instructed to be ‘mild’ malingerers. A failure rate of 11%, as defined by failing two or more tests, appears similar to that
328
Commentary / Journal of Psychosomatic Research 65 (2008) 327–328
seen in other general medical populations. The importance of not relying on one test is emphasized. Interestingly, the receipt of disability benefits bore no correlation to failure in effort testing. Cognitive effort testing is, of course, only a proxy measure of the degree of motoric ‘effort failure’ that may underlie other physical symptoms such as weakness and fatigue. Failure on cognitive effort tests may be specific to patients who present prominently with memory symptoms unexplained by disease. Indeed, all of the patients with unexplained symptoms who did fail had memory complaints. The study does not tell us whether patients with weakness, for example, have ‘effort failure’ when attempting to move their weak limb. It also does not exclude the possibilities (a) that such patients are compliant and effortful during testing but conscious in a desire to deceive at other times or (b) that the patient has genuine symptoms but willfully cannot be bothered to do the test properly. It is a study that would be useful if repeated in different populations, especially in a group of litigant patients with conversion symptoms. Henry Miller [15] thought that the detection of conscious versus unconscious intent depended on ‘nothing more infallible than one man's assessment of what is probably going on in another man's mind’. Perhaps neuroscience will never allow us to quantify the conscious intent of our patients. There are, however, common clinical features in patients with conversion symptoms that should persuade us that most of them are not simulating. These include consistent symptom descriptions between patients, bafflement and fear of symptoms, desire for investigations, and persistence of symptoms at follow-up. The study by Kemp et al. needs to be repeated in different clinical samples but does add some quantitative weight to the clinical impression that, whilst a proportion of patients with conversion symptoms may be exaggerating or even simulating, they appear to be a small minority.
References [1] Charcot JM. Clinical lectures on diseases of the nervous system, vol. 3. London: New Sydenham Society, 1889. [2] Lempert T, Brandt T, Dieterich M, Huppert D. How to identify psychogenic disorders of stance and gait. A video study in 37 patients. J Neurol 1991;238:140–6. [3] Ward NS, Oakley DA, Frackowiak RS, Halligan PW. Differential brain activations during intentionally simulated and subjectively experienced paralysis. Cogn Neuropsychiatry 2003;8:295–312. [4] Spence SA, Crimlisk HL, Cope H, Ron MA, Grasby PM. Discrete neurophysiological correlates in prefrontal cortex during hysterical and feigned disorder of movement. Lancet 2000;355:1243–4. [5] Stone J, Zeman A, Simonotto E, Meyer M, Azuma R, Flett S, et al. FMRI in patients with motor conversion symptoms and controls with simulated weakness. Psychosom Med 2007;69:961–9. [6] Lorenz J, Kunze K, Bromm B. Differentiation of conversive sensory loss and malingering by P300 in a modified oddball task. NeuroReport 1998;9:187–91. [7] Maruff P, Velakoulis D. The voluntary control of motor imagery. Imagined movements in individuals with feigned motor impairment and conversion disorder. Neuropsychologia 2000;38:1251–60. [8] Stone J, Zeman A, Sharpe M. Functional weakness and sensory disturbance. J Neurol Neurosurg Psychiatry 2002;73:241–5. [9] Bass C. Factitious disorders and malingering. In: Halligan P, Bass C, Marshall JC, editors. Contemporary approaches to the study of hysteria. Oxford: Oxford University Press, 2001. [10] Kemp S, Coughlan AK, Rowbottom C, Wilkinson K, Teggart V, Baker G. The base rate of effort test failure in patients with medically unexplained symptoms. J Psychosom Res 2008;65:319–25. [11] Hill SK, Ryan LM, Kennedy CH. The relationship between measures of declarative memory and the test of memory malingering in patients with and without temporal lobe dysfunction. J Forensic Neuropsychol 2003;3:1–18. [12] Cragar DE, Berry DT, Fakhoury TA, Cibula JE, Schmitt FA. Performance of patients with epilepsy or psychogenic non-epileptic seizures on four measures of effort. Clin Neuropsychol 2006;20: 552–66. [13] Dodrill CB. Do patients with psychogenic nonepileptic seizures produce trustworthy findings on neuropsychological tests? Epilepsia 2008;49:691–5. [14] Drane DL, Williamson DJ, Stroup ES, Holmes MD, Jung M, Koerner E, et al. Cognitive impairment is not equal in patients with epileptic and psychogenic nonepileptic seizures. Epilepsia 2006;47:1879–86. [15] Miller H. Accident neurosis II. Br Med J 1961;i:992–8.
Commentary
Effort testing in patients with neurological symptoms unexplained by disease Jon Stone⁎ Department Clinical Neurosciences, University of Edinburgh, Western General Hospital, Edinburgh, UK Received 2 May 2008; received in revised form 6 May 2008; accepted 6 May 2008
When most people think about patients with neurological symptoms unexplained by disease (e.g., conversion symptoms such as paralysis or blackouts), one of several predictable themes usually emerge. Since the symptoms presented relate to a problem with the voluntary action of the nervous system, to what extent could these patients' symptoms be voluntarily or consciously manufactured? Can a disorder of voluntary action really be involuntary? Such questions do not hang so heavily over other symptoms unexplained by disease such as irritable bowel syndrome or chronic pain. This question has rarely been approached experimentally. Charcot [1] claimed to demonstrate the difference between hysterical catalepsy (sustained limb posturing) and malingered catalepsy with the use of tremor recordings. He thought the issue of simulation in ‘hysteria’ was ‘only a bugbear, before which the fearful and novice alone are stopped’. More recently, small studies have shown how poor doctors are at distinguishing ‘psychogenic’ or ‘hypnotic’ conversion symptoms from consciously simulated symptoms [2,3]. Some functional imaging [3–5], neurophysiological [6], and neuropsychological studies [7] have shown differences between simulated symptoms and conversion symptoms but with no consistent answers. At the bedside, all of the ‘positive’ physical signs of conversion symptoms also occur in
⁎ Department Clinical Neurosciences, Western General Hospital, Edinburgh EH4 2XU, UK. Tel.: +44 131 537 1167; fax: +44 0131 537 1132. E-mail address: [email protected]. 0022-3999/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2008.05.004
factitious states [8]. Hence, authors past and present have therefore placed weight on the detection of major inconsistencies in the history, a confession or marked discrepancies on covert surveillance to diagnose factitious neurological symptoms or malingering [9]. However, because these factors are unlikely to apply in everyday practice, the question of poor effort, exaggeration, or simulation usually remains. The study by Kemp et al. [10] in this issue of the journal—‘The base rate of effort test failure in patients with medically unexplained symptoms’—is therefore an especially welcome contribution to this area. Effort tests have been in routine use for many years. They are cognitive tests that are easier than they appear, so that even someone with severe cognitive impairment should be able to pass or score above chance. Three recent studies have found similar rates of effort test failure between patients with nonepileptic attacks and patients with epilepsy [11–13], whilst one did not [14]. However, this is the first study to compare a clinical population with conversion symptoms against subjects instructed to ‘malinger’. Patients with neurological symptoms unexplained by disease have high rates of cognitive symptoms even when this is not their main complaint (as evidenced by the figure of 71% of patients in this study). If part of the reason for weakness or other symptoms in these patients is a lack of effort, then it seems reasonable to assume that this might be reflected in a poor score on cognitive effort testing as well. It may come as a surprise (and a challenge) to some that Kemp et al. found a failure rate of only 11% in a sample of 43 of these patients, in contrast to 90% in a group of subjects instructed to be ‘mild’ malingerers. A failure rate of 11%, as defined by failing two or more tests, appears similar to that
328
Commentary / Journal of Psychosomatic Research 65 (2008) 327–328
seen in other general medical populations. The importance of not relying on one test is emphasized. Interestingly, the receipt of disability benefits bore no correlation to failure in effort testing. Cognitive effort testing is, of course, only a proxy measure of the degree of motoric ‘effort failure’ that may underlie other physical symptoms such as weakness and fatigue. Failure on cognitive effort tests may be specific to patients who present prominently with memory symptoms unexplained by disease. Indeed, all of the patients with unexplained symptoms who did fail had memory complaints. The study does not tell us whether patients with weakness, for example, have ‘effort failure’ when attempting to move their weak limb. It also does not exclude the possibilities (a) that such patients are compliant and effortful during testing but conscious in a desire to deceive at other times or (b) that the patient has genuine symptoms but willfully cannot be bothered to do the test properly. It is a study that would be useful if repeated in different populations, especially in a group of litigant patients with conversion symptoms. Henry Miller [15] thought that the detection of conscious versus unconscious intent depended on ‘nothing more infallible than one man's assessment of what is probably going on in another man's mind’. Perhaps neuroscience will never allow us to quantify the conscious intent of our patients. There are, however, common clinical features in patients with conversion symptoms that should persuade us that most of them are not simulating. These include consistent symptom descriptions between patients, bafflement and fear of symptoms, desire for investigations, and persistence of symptoms at follow-up. The study by Kemp et al. needs to be repeated in different clinical samples but does add some quantitative weight to the clinical impression that, whilst a proportion of patients with conversion symptoms may be exaggerating or even simulating, they appear to be a small minority.
References [1] Charcot JM. Clinical lectures on diseases of the nervous system, vol. 3. London: New Sydenham Society, 1889. [2] Lempert T, Brandt T, Dieterich M, Huppert D. How to identify psychogenic disorders of stance and gait. A video study in 37 patients. J Neurol 1991;238:140–6. [3] Ward NS, Oakley DA, Frackowiak RS, Halligan PW. Differential brain activations during intentionally simulated and subjectively experienced paralysis. Cogn Neuropsychiatry 2003;8:295–312. [4] Spence SA, Crimlisk HL, Cope H, Ron MA, Grasby PM. Discrete neurophysiological correlates in prefrontal cortex during hysterical and feigned disorder of movement. Lancet 2000;355:1243–4. [5] Stone J, Zeman A, Simonotto E, Meyer M, Azuma R, Flett S, et al. FMRI in patients with motor conversion symptoms and controls with simulated weakness. Psychosom Med 2007;69:961–9. [6] Lorenz J, Kunze K, Bromm B. Differentiation of conversive sensory loss and malingering by P300 in a modified oddball task. NeuroReport 1998;9:187–91. [7] Maruff P, Velakoulis D. The voluntary control of motor imagery. Imagined movements in individuals with feigned motor impairment and conversion disorder. Neuropsychologia 2000;38:1251–60. [8] Stone J, Zeman A, Sharpe M. Functional weakness and sensory disturbance. J Neurol Neurosurg Psychiatry 2002;73:241–5. [9] Bass C. Factitious disorders and malingering. In: Halligan P, Bass C, Marshall JC, editors. Contemporary approaches to the study of hysteria. Oxford: Oxford University Press, 2001. [10] Kemp S, Coughlan AK, Rowbottom C, Wilkinson K, Teggart V, Baker G. The base rate of effort test failure in patients with medically unexplained symptoms. J Psychosom Res 2008;65:319–25. [11] Hill SK, Ryan LM, Kennedy CH. The relationship between measures of declarative memory and the test of memory malingering in patients with and without temporal lobe dysfunction. J Forensic Neuropsychol 2003;3:1–18. [12] Cragar DE, Berry DT, Fakhoury TA, Cibula JE, Schmitt FA. Performance of patients with epilepsy or psychogenic non-epileptic seizures on four measures of effort. Clin Neuropsychol 2006;20: 552–66. [13] Dodrill CB. Do patients with psychogenic nonepileptic seizures produce trustworthy findings on neuropsychological tests? Epilepsia 2008;49:691–5. [14] Drane DL, Williamson DJ, Stroup ES, Holmes MD, Jung M, Koerner E, et al. Cognitive impairment is not equal in patients with epileptic and psychogenic nonepileptic seizures. Epilepsia 2006;47:1879–86. [15] Miller H. Accident neurosis II. Br Med J 1961;i:992–8.