Neurophysiologie Clinique/Clinical Neurophysiology (2014) 44, 301—304
Disponible en ligne sur
ScienceDirect www.sciencedirect.com
EDITORIAL/ÉDITORIAL
Neurophysiology of conversive disorders Neurophysiologie clinique et conversion
KEYWORDS Conversion; Hysteria; Lying; Malingering; Cognitive neuropsychiatry; Expertise; Forensic
MOTS CLÉS Conversion ; Hystérie ; Mensonge ; Simulation ; Neuropsychiatrie cognitive ; Expertise ; Médicolégal
This special NCCN issue on ‘‘conversion disorders’’ brings together several lectures that were given during the winter meeting of the ‘‘Société de neurophysiologie clinique de langue franc ¸aise’’, which was held in Paris in January 2013. This meeting was exceptional in many respects, notably its eclecticism: both fundamental and clinical presentations given by neurologists, psychiatrists, and psychologists. This meeting was also enhanced by a lecture given by the American novelist Siri Hustvedt, whom I thank warmly for having participated in this issue. There are several reasons to devote a special issue of a Neurophysiological Journal to ‘‘conversive disorders’’, even if only two out of its 13 papers are specifically devoted to clinical neurophysiology (CN), either as a diagnostic tool in http://dx.doi.org/10.1016/j.neucli.2014.09.062 0987-7053/© 2014 Published by Elsevier Masson SAS.
psychogenic movement disorders (Emmanuelle Apartis) or as a possible adjunct to therapeutics (Dominique Parain). Among these reasons, I would like to briefly emphasize three aspects: • the current CN contribution for the assessment of neural information processing in conversive disorders; • an update on some forensic applications of CN; • and the history of conversive disorders as an illustration of the emergence of neuropsychiatry as an autonomous discipline, helping re-define the domains of both neurology and psychiatry.
Neural information processing in conversive disorders Paradoxically, most papers dealing with CN in conversive disorders are limited to single-case studies. Therefore, most advice on the usefulness of CN as a diagnostic tool in conversive disorders are limited to ‘‘expert opinions’’ rather than evidence. The most likely explanation of this paradox is methodological: given the absence of a gold standard and the retrospective character of most diagnoses of conversive disorders, it is almost impossible to amass suitably homogeneous populations of conversive patients meeting publication criteria. There are only two neurophysiological quasi-evidences. Firstly, the ‘‘exogenous’’ components of evoked potentials are normal in sensory deficits, and motor evoked potentials are normal in motor deficits of conversive origin. Secondly, P300 seems to be altered in sensory deficits of conversive origin, which differentiates this situation from malingering (Fig. 1). However, CN has not succeeded in explaining what happens between reception at the cortical level and conscious perception. This could be considered as surprising
302
Editorial/Éditorial
Figure 1 Neurophysiological detection of malingering. P300 recording in a 59-year-old patient declaring a total hearing loss of left ear following head trauma; behavioural discrepancies, suspicion of simulation. Analysis time: 1 second. A: (left waveforms) left ear stimulation, the subject is instructed to move the left finger in response to rare stimuli; there are no gestures and the subject declares that he didn’t hear any stimulus: there is a normal N100 —P200 complex, indicating preserved reception at least by the primary auditory cortex, no further differentiation between frequent and rare stimuli; (right waveforms) we notice the patient that although there was no gesture of the left hand, we could not rule out that there was, indeed, a small gesture of the left foot; we tell him we will repeat the recording in order to check it; the N100 —P200 complex is unchanged but there is now a readily reproducible P300 , whose appearance is explained by the production of a no—go response by this patient who must absolutely avoid to respond to well-perceived stimuli he pretends not to perceive. B: (analysis time: 500 msec) comparison between responses obtained to right ear stimulation (declared normal, left waveforms) and left ear stimulation (declared cophotic: right waveforms): note that both responses are strictly comparable. In this case, P300 recording demonstrates that left ear stimuli were not only correctly received by the auditory cortex but also considered as significant, which implies that there were, indeed, consciously perceived. This makes a diagnosis of malingering most highly probable. Adapted from [1], with permission of the first editor.
and frustrating, given the huge arsenal of available neurophysiological tools for the study of the successive steps between cortical reception and perception. Given this failure of CN, one is tempted to look to other functional methods, i.e., functional neuroimaging, a topic that is dealt with in three papers by Patrik Vuilleumier,
Valerie Voon and Catherine Thomas. These papers should be compared with that of Audrey Vanhaudenhuyse on the neurophysiology of hypnosis. All articles converge toward the hypothesis that both conversion disorders and hypnosis might result from an altered access to internal motor or sensory representations of the self, with a key role for
Editorial/Éditorial
303
the ventromedial prefrontal cortex in conversive disorders (integrating information with affective relevance) and for the precuneus (sensory or agency representations) in both conversive disorders and hypnosis. Hopefully, these hypotheses obtained through costly techniques of limited access should inspire the design of new neurophysiological, more bedside accessible, paradigms.
compensation) or unconscious (internal reward associated with playing out the sick role) character of intentionality. We present a case in which this conscious and intentional character of lying could, with the highest degree of confidence, be demonstrated neurophysiologically (Fig. 1).
Forensic implications: objectivation and lying
As shown in the papers of Siri Hustvedt and Marc Crommelinck on historical perspectives, one remarkable feature of the conversive disorder has been its successive affiliation first to the neurological domain and then to the psychiatric one, followed by ‘‘its gradual reinstatement within the field of neurology and CN’’. This latter field, including studies of ‘‘brain software’’, actually corresponds to ‘‘neuropsychiatry’’. Thus, this special NCCN issue illustrates the emergence of neuropsychiatry as an autonomous discipline re-defining the respective domains of neurology and psychiatry. As pointed out by Siri Hustvedt and Marc Crommelinck, two factors contributed to the emergence of neuropsychiatry: the turning point of cognitive neurosciences during the 1960s and 1970s; and, two decades later on, the meteoric progress of functional imaging techniques, particularly positron emission tomography (PET) and functional MRI (fMRI). Far from disposing of the need for CN, the rapid development of both PET and MRI have contributed to enhance the role of CN in at least three ways:
The objectivation of a deficit consists of its demonstration through non-invasive methods whose results cannot be influenced by the patient’s own initiative. This is classically performed through using structural (structural imaging) or functional (patient history, neurological or neuropsychological examination, CN, non-invasive functional imaging) methods. By definition, a deficit corresponds to a functional entity, whose evaluation can only be achieved through a functional method. Though cerebral computerised tomography (CT) or magnetic resonance imaging (MRI) can objectivize a structural lesion, or provide indirect arguments in favour of a pathophysiological process compatible with a given functional deficit, these techniques do not objectivize the deficit itself and, a fortiori, do not allow its quantification. So to what extent can a functional technique be considered as ‘‘objective’’? Sometimes, the response is evident. Thus, for an experienced neurologist, a Babinski sign, clonus, dysconjugate eye movements or cogwheel rigidity, for example, clearly correspond to well-identified nervous dysfunction and cannot be intentionally produced. The same holds true for nerve-conduction or needle-EMG studies, evoked potentials, and EEG. Of course the neurologist or the neurophysiologist should ensure that these functional alterations are, indeed, related to the deficit he wants to objectivize. Sometimes, a functional technique becomes objective after it has been sophisticated to the point that even a well-informed patient is unable to voluntarily provide a semiological pattern that would be compatible with the deficit he wants to put forward. Several interesting examples are provided in the paper of Jon Stone, dealing with functional neurological deficits, and in that of Markus Reuber showing how a careful examination of patient’s story may help differentiate epileptic from non-epileptic psychogenic seizures. Neurophysiologically, the paper of Emmanuelle Apartis shows how specific examination strategies coupled with careful recording techniques help identify psychogenic tremor or myoclonus. The issue of lying, i.e., ‘‘to make a believed-false statement to another person with the intention that the statement be believed to be true’’ is central to the medicolegal process. In his paper ‘‘Lying in Neuropsychology’’, Xavier Seron attempts to situate the notion of ‘‘malingering’’ with respect to ‘‘factitious’’ and ‘‘somatoform’’ disorders. While the boundary between ‘‘malingering’’ and ‘‘somatoform’’ disorders looks rather evident, based on intentionality, this last criterion doesn’t help differentiate ‘‘malingering’’ from ‘‘factitious’’ disorders, in which case one should introduce as a second criterion the conscious (search for financial or material
The emergence of neuropsychiatry
• by underlining the importance of functional assessment; • by increasing the yield of CN by providing the anatomical constraints that CN lacks to solve the inverse problem; • by highlighting the specific weaknesses of functional neuroimaging methods (cost, low accessibility, poor temporal resolution), functional imaging techniques like PET and fMRI have helped better define niche for CN. Seen like this, I consider that neuropsychiatry actually merges the domains of both functional neurology and cognitive neuropsychiatry. Whether or not neuropsychiatry as an autonomous entity will limit the prerogatives of neurologists and psychiatrists will depend on how the two disciplines react to its emergence. In my opinion, both neurologists and psychiatrists are welcome in this domain, provided that they accept to make the intellectual effort required to improve their knowledge of brain software and its relation to cognitive neurosciences. If they agree to do this, neuropsychiatry can provide both specialties with alternative explanations and tools, helping them solve problems that were previously inaccessible based on isolated structural or psychodynamic models. Moreover, there undoubtedly remains a very specific space for psychiatry, which the emergence of neuropsychiatry could help better define. Thus, the paper of Lisa Ouss on children and adolescents demonstrates the relative fruitlessness of the neurobiological approach and underlines the interest of a psychodynamic model in the understanding of the genesis of conversive disorders; and the paper of Olivier Cottencin underlines the key role of the psychiatrist as a coordinator with other specialists and general practitioners for treatments that often require long-term intervention.
304
Final comment Before leaving you to read this special issue, I would like to thank Caroline Perchet who just finished her 17-year term as an Editorial Assistant. Caroline, you played a key role in the continuity of the Journal when I took over from Luis Garcia Larrea in 2005, and you helped me quite efficiently in the gradual transition from paper to electronics. Thank you for your cheerful and efficient collaboration. I also take this opportunity to introduce Dr Aileen McGonigal, and thank her for the critical role she played in the preparation of this issue. As a native English speaker and a UK-trained neurologist working in France, Aileen worked with all the French authors to improve the English texts. Much more than a role as translator, her collaboration was unanimously acknowledged by all her interlocutors and myself for her scientific input. It has been my greatest
Editorial/Éditorial pleasure to learn her acceptance to work as the Managing Editor of NCCN. Welcome Aileen, I trust that you will play a key role in the future development of our Journal.
Reference [1] Guérit JM. Neurophysiologie clinique et neurologie. In: Seron X, Vanderlinden M, editors. Traité de neuropsychologie clinique de l’adulte. Louvain-la-Neuve: de Boeck & Solal; 2014. p. 41—60.
chief editor, NCCN J.-M. Guérit Clinique Edith Cavell, rue Edith Cavell, 32, 1180 Brussels, Belgium E-mail address: [email protected]
Disponible en ligne sur
ScienceDirect www.sciencedirect.com
EDITORIAL/ÉDITORIAL
Neurophysiology of conversive disorders Neurophysiologie clinique et conversion
KEYWORDS Conversion; Hysteria; Lying; Malingering; Cognitive neuropsychiatry; Expertise; Forensic
MOTS CLÉS Conversion ; Hystérie ; Mensonge ; Simulation ; Neuropsychiatrie cognitive ; Expertise ; Médicolégal
This special NCCN issue on ‘‘conversion disorders’’ brings together several lectures that were given during the winter meeting of the ‘‘Société de neurophysiologie clinique de langue franc ¸aise’’, which was held in Paris in January 2013. This meeting was exceptional in many respects, notably its eclecticism: both fundamental and clinical presentations given by neurologists, psychiatrists, and psychologists. This meeting was also enhanced by a lecture given by the American novelist Siri Hustvedt, whom I thank warmly for having participated in this issue. There are several reasons to devote a special issue of a Neurophysiological Journal to ‘‘conversive disorders’’, even if only two out of its 13 papers are specifically devoted to clinical neurophysiology (CN), either as a diagnostic tool in http://dx.doi.org/10.1016/j.neucli.2014.09.062 0987-7053/© 2014 Published by Elsevier Masson SAS.
psychogenic movement disorders (Emmanuelle Apartis) or as a possible adjunct to therapeutics (Dominique Parain). Among these reasons, I would like to briefly emphasize three aspects: • the current CN contribution for the assessment of neural information processing in conversive disorders; • an update on some forensic applications of CN; • and the history of conversive disorders as an illustration of the emergence of neuropsychiatry as an autonomous discipline, helping re-define the domains of both neurology and psychiatry.
Neural information processing in conversive disorders Paradoxically, most papers dealing with CN in conversive disorders are limited to single-case studies. Therefore, most advice on the usefulness of CN as a diagnostic tool in conversive disorders are limited to ‘‘expert opinions’’ rather than evidence. The most likely explanation of this paradox is methodological: given the absence of a gold standard and the retrospective character of most diagnoses of conversive disorders, it is almost impossible to amass suitably homogeneous populations of conversive patients meeting publication criteria. There are only two neurophysiological quasi-evidences. Firstly, the ‘‘exogenous’’ components of evoked potentials are normal in sensory deficits, and motor evoked potentials are normal in motor deficits of conversive origin. Secondly, P300 seems to be altered in sensory deficits of conversive origin, which differentiates this situation from malingering (Fig. 1). However, CN has not succeeded in explaining what happens between reception at the cortical level and conscious perception. This could be considered as surprising
302
Editorial/Éditorial
Figure 1 Neurophysiological detection of malingering. P300 recording in a 59-year-old patient declaring a total hearing loss of left ear following head trauma; behavioural discrepancies, suspicion of simulation. Analysis time: 1 second. A: (left waveforms) left ear stimulation, the subject is instructed to move the left finger in response to rare stimuli; there are no gestures and the subject declares that he didn’t hear any stimulus: there is a normal N100 —P200 complex, indicating preserved reception at least by the primary auditory cortex, no further differentiation between frequent and rare stimuli; (right waveforms) we notice the patient that although there was no gesture of the left hand, we could not rule out that there was, indeed, a small gesture of the left foot; we tell him we will repeat the recording in order to check it; the N100 —P200 complex is unchanged but there is now a readily reproducible P300 , whose appearance is explained by the production of a no—go response by this patient who must absolutely avoid to respond to well-perceived stimuli he pretends not to perceive. B: (analysis time: 500 msec) comparison between responses obtained to right ear stimulation (declared normal, left waveforms) and left ear stimulation (declared cophotic: right waveforms): note that both responses are strictly comparable. In this case, P300 recording demonstrates that left ear stimuli were not only correctly received by the auditory cortex but also considered as significant, which implies that there were, indeed, consciously perceived. This makes a diagnosis of malingering most highly probable. Adapted from [1], with permission of the first editor.
and frustrating, given the huge arsenal of available neurophysiological tools for the study of the successive steps between cortical reception and perception. Given this failure of CN, one is tempted to look to other functional methods, i.e., functional neuroimaging, a topic that is dealt with in three papers by Patrik Vuilleumier,
Valerie Voon and Catherine Thomas. These papers should be compared with that of Audrey Vanhaudenhuyse on the neurophysiology of hypnosis. All articles converge toward the hypothesis that both conversion disorders and hypnosis might result from an altered access to internal motor or sensory representations of the self, with a key role for
Editorial/Éditorial
303
the ventromedial prefrontal cortex in conversive disorders (integrating information with affective relevance) and for the precuneus (sensory or agency representations) in both conversive disorders and hypnosis. Hopefully, these hypotheses obtained through costly techniques of limited access should inspire the design of new neurophysiological, more bedside accessible, paradigms.
compensation) or unconscious (internal reward associated with playing out the sick role) character of intentionality. We present a case in which this conscious and intentional character of lying could, with the highest degree of confidence, be demonstrated neurophysiologically (Fig. 1).
Forensic implications: objectivation and lying
As shown in the papers of Siri Hustvedt and Marc Crommelinck on historical perspectives, one remarkable feature of the conversive disorder has been its successive affiliation first to the neurological domain and then to the psychiatric one, followed by ‘‘its gradual reinstatement within the field of neurology and CN’’. This latter field, including studies of ‘‘brain software’’, actually corresponds to ‘‘neuropsychiatry’’. Thus, this special NCCN issue illustrates the emergence of neuropsychiatry as an autonomous discipline re-defining the respective domains of neurology and psychiatry. As pointed out by Siri Hustvedt and Marc Crommelinck, two factors contributed to the emergence of neuropsychiatry: the turning point of cognitive neurosciences during the 1960s and 1970s; and, two decades later on, the meteoric progress of functional imaging techniques, particularly positron emission tomography (PET) and functional MRI (fMRI). Far from disposing of the need for CN, the rapid development of both PET and MRI have contributed to enhance the role of CN in at least three ways:
The objectivation of a deficit consists of its demonstration through non-invasive methods whose results cannot be influenced by the patient’s own initiative. This is classically performed through using structural (structural imaging) or functional (patient history, neurological or neuropsychological examination, CN, non-invasive functional imaging) methods. By definition, a deficit corresponds to a functional entity, whose evaluation can only be achieved through a functional method. Though cerebral computerised tomography (CT) or magnetic resonance imaging (MRI) can objectivize a structural lesion, or provide indirect arguments in favour of a pathophysiological process compatible with a given functional deficit, these techniques do not objectivize the deficit itself and, a fortiori, do not allow its quantification. So to what extent can a functional technique be considered as ‘‘objective’’? Sometimes, the response is evident. Thus, for an experienced neurologist, a Babinski sign, clonus, dysconjugate eye movements or cogwheel rigidity, for example, clearly correspond to well-identified nervous dysfunction and cannot be intentionally produced. The same holds true for nerve-conduction or needle-EMG studies, evoked potentials, and EEG. Of course the neurologist or the neurophysiologist should ensure that these functional alterations are, indeed, related to the deficit he wants to objectivize. Sometimes, a functional technique becomes objective after it has been sophisticated to the point that even a well-informed patient is unable to voluntarily provide a semiological pattern that would be compatible with the deficit he wants to put forward. Several interesting examples are provided in the paper of Jon Stone, dealing with functional neurological deficits, and in that of Markus Reuber showing how a careful examination of patient’s story may help differentiate epileptic from non-epileptic psychogenic seizures. Neurophysiologically, the paper of Emmanuelle Apartis shows how specific examination strategies coupled with careful recording techniques help identify psychogenic tremor or myoclonus. The issue of lying, i.e., ‘‘to make a believed-false statement to another person with the intention that the statement be believed to be true’’ is central to the medicolegal process. In his paper ‘‘Lying in Neuropsychology’’, Xavier Seron attempts to situate the notion of ‘‘malingering’’ with respect to ‘‘factitious’’ and ‘‘somatoform’’ disorders. While the boundary between ‘‘malingering’’ and ‘‘somatoform’’ disorders looks rather evident, based on intentionality, this last criterion doesn’t help differentiate ‘‘malingering’’ from ‘‘factitious’’ disorders, in which case one should introduce as a second criterion the conscious (search for financial or material
The emergence of neuropsychiatry
• by underlining the importance of functional assessment; • by increasing the yield of CN by providing the anatomical constraints that CN lacks to solve the inverse problem; • by highlighting the specific weaknesses of functional neuroimaging methods (cost, low accessibility, poor temporal resolution), functional imaging techniques like PET and fMRI have helped better define niche for CN. Seen like this, I consider that neuropsychiatry actually merges the domains of both functional neurology and cognitive neuropsychiatry. Whether or not neuropsychiatry as an autonomous entity will limit the prerogatives of neurologists and psychiatrists will depend on how the two disciplines react to its emergence. In my opinion, both neurologists and psychiatrists are welcome in this domain, provided that they accept to make the intellectual effort required to improve their knowledge of brain software and its relation to cognitive neurosciences. If they agree to do this, neuropsychiatry can provide both specialties with alternative explanations and tools, helping them solve problems that were previously inaccessible based on isolated structural or psychodynamic models. Moreover, there undoubtedly remains a very specific space for psychiatry, which the emergence of neuropsychiatry could help better define. Thus, the paper of Lisa Ouss on children and adolescents demonstrates the relative fruitlessness of the neurobiological approach and underlines the interest of a psychodynamic model in the understanding of the genesis of conversive disorders; and the paper of Olivier Cottencin underlines the key role of the psychiatrist as a coordinator with other specialists and general practitioners for treatments that often require long-term intervention.
304
Final comment Before leaving you to read this special issue, I would like to thank Caroline Perchet who just finished her 17-year term as an Editorial Assistant. Caroline, you played a key role in the continuity of the Journal when I took over from Luis Garcia Larrea in 2005, and you helped me quite efficiently in the gradual transition from paper to electronics. Thank you for your cheerful and efficient collaboration. I also take this opportunity to introduce Dr Aileen McGonigal, and thank her for the critical role she played in the preparation of this issue. As a native English speaker and a UK-trained neurologist working in France, Aileen worked with all the French authors to improve the English texts. Much more than a role as translator, her collaboration was unanimously acknowledged by all her interlocutors and myself for her scientific input. It has been my greatest
Editorial/Éditorial pleasure to learn her acceptance to work as the Managing Editor of NCCN. Welcome Aileen, I trust that you will play a key role in the future development of our Journal.
Reference [1] Guérit JM. Neurophysiologie clinique et neurologie. In: Seron X, Vanderlinden M, editors. Traité de neuropsychologie clinique de l’adulte. Louvain-la-Neuve: de Boeck & Solal; 2014. p. 41—60.
chief editor, NCCN J.-M. Guérit Clinique Edith Cavell, rue Edith Cavell, 32, 1180 Brussels, Belgium E-mail address: [email protected]
