Hysterical conversion and brain function

Laboratory for Behavioral Neurology and Imaging of Cognition, Clinic of Neurology, University University of Geneva, Geneva, Switzerland.
Progress in brain research (Impact Factor: 2.83). 02/2005; 150:309-29. DOI: 10.1016/S0079-6123(05)50023-2
Source: PubMed


Hysterical conversion disorders represent "functional" or unexplained neurological deficits such as paralysis or somatosensory losses that are not explained by organic lesions in the nervous system, but arise in the context of "psychogenic" stress or emotional conflicts. After more than a century of both clinical and theoretical interest, the exact nature of such emotional disorders responsible for hysterical symptoms, and their functional consequences on neural systems in the brain, still remain largely unknown. However, several recent studies have used functional brain imaging techniques (such as EEG, fMRI, PET, or SPECT) in the attempt to identify specific neural correlates associated with hysterical conversion symptoms. This article presents a general overview of these findings and of previous neuropsychologically based accounts of hysteria. Functional neuroimaging has revealed selective decreases in the activity of frontal and subcortical circuits involved in motor control during hysterical paralysis, decreases in somatosensory cortices during hysterical anesthesia, or decreases in visual cortex during hysterical blindness. Such changes are usually not accompanied by any significant changes in elementary stages of sensory or motor processing as measured by evoked potentials, although some changes in later stages of integration (such as P300 responses) have been reported. On the other hand, several neuroimaging results have shown increased activation in limbic regions, such as cingulate or orbitofrontal cortex during conversion symptoms affecting different sensory or motor modalities. Taken together, these data generally do not support previous proposals that hysteria might involve an exclusion of sensorimotor representations from awareness through attentional processes. They rather seem to point to a modulation of such representations by primary affective or stress-related factors, perhaps involving primitive reflexive mechanisms of protection and alertness that are partly independent of conscious control, and mediated by dynamic modulatory interactions between limbic and sensorimotor networks. A better understanding of the neuropsychobiological bases of hysterical conversion disorder might therefore be obtained by future imaging studies that compare different conversion symptoms and employ functional connectivity analyses. This should not only lead to improve clinical management of these patients, but also provide new insights on the brain mechanisms of self-awareness.

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Available from: Patrik Vuilleumier, Feb 04, 2015
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    • "It is distinguished from other " non-organic " movement disorders by a lack of conscious intention to deceive (Bass, 2001). Symptoms are thought to arise from underlying psychological stressors such as trauma or conflict, but the neural mechanisms remain unknown (Scott & Anson, 2009; Vuilleumier, 2005). The neurobiology underpinning conversion paresis and other conversion disorders remains mysterious. "
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    ABSTRACT: Conversion paresis is the presence of unexplained weakness without detectable neuropathology that is not feigned. To examine the 'abnormal preparation' and 'disrupted execution' hypotheses proposed to explain the movement deficits in conversion paresis, electroencephalographic, electromyographic and kinematic measures were recorded during motor preparation and execution. Six patients with unilateral upper limb conversion weakness, 24 participants feigning weakness and 12 control participants performed a 2-choice precued reaction time task. Precues provided advance information about the responding hand or finger. Patients and feigners demonstrated similar diminished force, longer movement time and extended duration of muscle activity in their symptomatic limb. Patients showed significantly suppressed contingent negative variation (CNV) amplitudes, but only when the symptomatic limb was precued. Despite the similarity in performance measures, this CNV suppression was not seen in feigners. Diminished CNV for symptomatic hand precues may reflect engagement of an inhibitory mechanism suppressing cortical activity related to preparatory processes. Copyright © 2015. Published by Elsevier B.V.
    Biological psychology 05/2015; 109. DOI:10.1016/j.biopsycho.2015.04.009 · 3.40 Impact Factor
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    • "The onset and exacerbation of CD symptoms have been linked to psychological factors like trauma or stress, suggesting that psychological mechanisms play an important role [2] [3]. Despite a long history of speculations about the causes of CD, the mechanisms behind the syndrome are not well understood [4] [5] [6]. Against this background, there is disagreement as to whether the name 'conversion disorder' is appropriate in the first place, since the term already implies a (as of yet unproven) specific psychological etiology [7]. "
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    ABSTRACT: Current theories of conversion disorder (CD) propose that motor symptoms are related to heightened self-monitoring and excessive cognitive control of movements. We tested this hypothesis using quantification of performance on a continuous perceptuo-motor task involving quiet standing. Twelve CD patients and matched controls maintained static balance on a force platform under various attention conditions: (1) with eyes open; (2) with eyes closed (requiring enhanced attention to proprioceptive information to regulate posture); and (3) while performing an attention demanding cognitive task. Compared to controls, CD patients displayed a greater decrease in postural stability in the 'eyes-closed' versus 'eyes-open' condition. In contrast, cognitive distraction led to a normalization of balance in CD. Moreover, sensitivity to the balance interventions correlated significantly with trauma reports and dissociative symptoms. These results indicate that attention plays a crucial role in postural control in CD. More specifically, patients seem to inadvertently use deliberate control of posture (i.e., cognitive investment) of an otherwise nearly automatized perceptuo-motor task. Attentional distraction resulted in a temporary normalization of balance, which may be used to train individuals with CD to guide their attention in a more effective way. Copyright © 2014 Elsevier Inc. All rights reserved.
    Journal of Psychosomatic Research 11/2014; 78(3). DOI:10.1016/j.jpsychores.2014.11.009 · 2.74 Impact Factor
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    • "Systematic scientific investigations to elucidate the neural mechanisms by which conversion disorders may alter motor or sensory functions began to appear in the late 60s and 70s, with the emergence of EEG recordings and the discovery of specific neurophysiological markers for different stages of perceptual processing and response making. While basic neurophysiological measures used in clinical assessment (such visual, somatosensory, auditory, or motor evoked potentials) are typically normal, and may thus help to establish the diagnosis of conversion disorder, some alterations have however been reported for more sophisticated measures associated with more complex task conditions or discriminative abilities (for more detailed review see [105] [106]). Most of these findings resemble modulations also known to be governed by attention, motivation, habituation , and/or expectation factors. "
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    ABSTRACT: Conversion disorders are defined as neurological symptoms arising without organic damage to the nervous system, presumably in relation to various emotional stress factors, but the exact neural substrates of these symptoms and the mechanisms responsible for their production remain poorly understood. In the past 15 years, novel insights have been gained with the advent of functional neuroimaging studies in patients suffering from conversion disorders in both motor and non-motor (e.g. somatosensory, visual) domains. Several studies have also compared brain activation patterns in conversion to those observed during hypnosis, where similar functional losses can be evoked by suggestion. The current review summarizes these recent results and the main neurobiological hypotheses proposed to account for conversion symptoms, in particular motor deficits. An emerging model points to an important role of ventromedial prefrontal cortex (VMPFC), precuneus, and perhaps other limbic structures (including amygdala), all frequently found to be hyperactivated in conversion disorders in parallel to impaired recruitment of primary motor and/or sensory pathways at the cortical or subcortical (basal ganglia) level. These findings are only partly shared with hypnosis, where increases in precuneus predominate, together with activation of attentional control systems, but without any activation of VMPFC. Both VMPFC and precuneus are key regions for access to internal representations about the self, integrating information from memory and imagery with affective relevance (in VMPFC) and sensory or agency representations (in precuneus). It is therefore postulated that conversion deficits might result from an alteration of conscious sensorimotor functions and self-awareness under the influence of affective and sensory representations generated in these regions, which might promote certain patterns of behaviors in response to self-relevant emotional states.
    Neurophysiologie Clinique/Clinical Neurophysiology 10/2014; 44(4). DOI:10.1016/j.neucli.2014.01.003 · 1.24 Impact Factor
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