Functional brain imaging in a woman with spatial neglect due to conversion disorder

Modification of both functional neurological symptoms and neuroimaging patterns with a good anatomoclinical concordance: a case report

Background

In the nineteenth century, Jean Martin Charcot explained functional neurological disorder (formerly called conversion disorder) as a “psychodynamic” lesion. Numerous advances in neuroimaging have permitted identification of the neural underpinnings of this disorder.

Case presentation

Herein we describe a case of functional neurological disorder (FND) with initial left sensorimotor deficit, in-coordinated limb movements, neglect, clouded consciousness, slurred speech and a semiology of visual impairment. A single photon emission computed tomography (SPECT) showed a right thalamic hypoperfusion, which is rather concordant with the initial semiology. Later, the semiology changed, presenting with a predominantly neurovisual complex presentation. The second SPECT showed no more thalamic abnormalities but an hypoperfusion in the right temporo-occipital junction, right inferior parietal lobe and left superior frontal lobe, which is also rather concordant with the changing semiology.

Conclusions

This case illustrates the evolving neuroimaging patterns of FND but also the concordance between semiology and neuroimaging findings in FND supporting Charcot's theory of “dynamic lesion”.

The role of the anterior and midcingulate cortex in the neurobiology of functional neurologic disorder

Functional neurologic disorder (FND)/conversion disorder is a prevalent and disabling condition at the intersection of neurology and psychiatry. Clinicians often report feeling ill-equipped treating patients with FND, perpetuated by a historically limited understanding of neurobiologic disease mechanisms. In this review, we summarize the neuroimaging literature across the spectrum of sensorimotor FND, including functional imaging studies during rest, sensorimotor performance, and emotional-processing tasks as well as structural magnetic resonance imaging findings. Particular attention is given to studies implicating the anterior and middle cingulate cortex and related salience network structures (insula, amygdala, and periaqueductal gray) in the neurobiology of FND. Neuroimaging studies identify cingulo-insular functional alterations during rest, motor performance, and emotion processing in FND populations. The literature also supports that patients with FND exhibit heightened amygdalar and periaqueductal gray reactivity to emotionally valenced stimuli, enhanced coupling between amygdalar and motor control areas, and increased amygdalar volumes. The structural neuroimaging literature also implicates cingulo-insular areas in the pathophysiology of FND, though these findings require replication and clarification. While more research is needed to fully elucidate the pathophysiology of FND, salience network alterations appear present in some FND populations and can be contextualized using biopsychosocial models for FND.

Cortical thickness alterations linked to somatoform and psychological dissociation in functional neurological disorders

BACKGROUND

Links between dissociation and functional neurological disorder (FND)/conversion disorder are well-established, yet the pathophysiology of dissociation remains poorly understood. This MRI study investigated structural alterations associated with somatoform and psychological dissociation in FND. We hypothesized that multimodal, paralimbic cingulo-insular regions would relate to the severity of somatoform dissociation in patients with FND.

METHODS

FreeSurfer cortical thickness and subcortical volumetric analyses were performed in 26 patients with motor FND and 27 matched healthy controls. Patients with high dissociation as measured by the Somatoform Dissociation Questionnaire-20 (SDQ) or Dissociative Experiences Scale (DES) were compared to controls in stratified analyses. Within-group analyses were also performed with SDQ and DES scores in patients with FND. All cortical thickness analyses were whole-brain corrected at the cluster-wise level.

RESULTS

Patients with FND and high somatoform dissociation (SDQ > 35) showed reduced left caudal anterior cingulate cortex (ACC) cortical thickness compared to controls. In within-group analyses, SDQ scores inversely correlated with left caudal ACC cortical thickness in patients with FND. Depersonalization/derealization scores positively correlated with right lateral occipital cortical thickness. Both within-group findings remained statistically significant controlling for trait anxiety/depression, borderline personality disorder and post-traumatic stress disorder, adverse life events, and motor FND subtypes in post-hoc analyses.

CONCLUSION

Using complementary between-group and within-group analyses, an inverse association between somatoform dissociation and left caudal ACC cortical thickness was observed in patients with FND. A positive relationship was also appreciated between depersonalization/derealization severity and cortical thickness in visual association areas. These findings advance our neuropathobiological understanding of dissociation in FND. Hum Brain Mapp 39:428-439, 2018. © 2017 Wiley Periodicals, Inc.

Neural correlates of conversion disorder: overview and meta-analysis of neuroimaging studies on motor conversion disorder

BACKGROUND

Conversion Disorders (CD) are prevalent functional disorders. Although the pathogenesis is still not completely understood, an interaction of genetic, neurobiological, and psychosocial factors is quite likely. The aim of this study is to provide a systematic overview on imaging studies on CDs and investigate neuronal areas involved in Motor Conversion Disorders (MCD).

METHODS

A systematic literature search was conducted on CD. Subsequently a meta-analysis of functional neuroimaging studies on MCD was implemented using an Activation Likelihood Estimation (ALE). We calculated differences between patients and healthy controls as well as between affected versus unaffected sides in addition to an overall analysis in order to identify neuronal areas related to MCD.

RESULTS

Patients with MCD differ from healthy controls in the amygdala, superior temporal lobe, retrosplenial area, primary motor cortex, insula, red nucleus, thalamus, anterior as well as dorsolateral prefrontal and frontal cortex. When comparing affected versus unaffected sides, temporal cortex, dorsal anterior cingulate cortex, supramarginal gyrus, dorsal temporal lobe, anterior insula, primary somatosensory cortex, superior frontal gyrus and anterior prefrontal as well as frontal cortex show significant differences.

CONCLUSIONS

Neuronal areas seem to be involved in the pathogenesis, maintenance or as a result of MCD. Areas that are important for motor-planning, motor-selection or autonomic response seem to be especially relevant. Our results support the emotional unawareness theory but also underline the need of more support by conduction imaging studies on both CD and MCD.

Emotion-motion interactions in conversion disorder: an FMRI study

Objectives

To evaluate the neural correlates of implicit processing of negative emotions in motor conversion disorder (CD) patients.

Methods

An event related fMRI task was completed by 12 motor CD patients and 14 matched healthy controls using standardised stimuli of faces with fearful and sad emotional expressions in comparison to faces with neutral expressions. Temporal changes in the sensitivity to stimuli were also modelled and tested in the two groups.

Results

We found increased amygdala activation to negative emotions in CD compared to healthy controls in region of interest analyses, which persisted over time consistent with previous findings using emotional paradigms. Furthermore during whole brain analyses we found significantly increased activation in CD patients in areas involved in the ‘freeze response’ to fear (periaqueductal grey matter), and areas involved in self-awareness and motor control (cingulate gyrus and supplementary motor area).

Conclusions

In contrast to healthy controls, CD patients exhibited increased response amplitude to fearful stimuli over time, suggesting abnormal emotional regulation (failure of habituation / sensitization). Patients with CD also activated midbrain and frontal structures that could reflect an abnormal behavioral-motor response to negative including threatening stimuli. This suggests a mechanism linking emotions to motor dysfunction in CD.

An integrative neurocircuit perspective on psychogenic nonepileptic seizures and functional movement disorders: neural functional unawareness

Functional neurological disorder (conversion disorder) is a neurobehavioral condition frequently encountered by neurologists. Psychogenic nonepileptic seizure (PNES) and functional movement disorder (FMD) patients present to epileptologists and movement disorder specialists respectively, yet neurologists lack a neurobiological perspective through which to understand these enigmatic groups. Observational research studies suggest that PNES and FMD may represent variants of similar (or the same) conditions given that both groups exhibit a female predominance, have increased prevalence of mood-anxiety disorders, frequently endorse prior abuse, and share phenotypic characteristics. In this perspective article, neuroimaging studies in PNES and FMD are reviewed, and discussed using studies of emotional dysregulation, dissociation and psychological trauma in the context of motor control. Convergent neuroimaging findings implicate alterations in brain circuits mediating emotional expression, regulation and awareness (anterior cingulate and ventromedial prefrontal cortices, insula, amygdala, vermis), cognitive control and motor inhibition (dorsal anterior cingulate, dorsolateral prefrontal, inferior frontal cortices), self-referential processing and perceptual awareness (posterior parietal cortex, temporoparietal junction), and motor planning and coordination (supplementary motor area, cerebellum). Striatal-thalamic components of prefrontal-parietal networks may also play a role in pathophysiology. Aberrant medial prefrontal and amygdalar neuroplastic changes mediated by chronic stress may facilitate the development of functional neurological symptoms in a subset of patients. Improved biological understanding of PNES and FMD will likely reduce stigma and aid the identification of neuroimaging biomarkers guiding treatment development, selection, and prognosis. Additional research should investigate neurocircuit abnormalities within and across functional neurological disorder subtypes, as well as compare PNES and FMD with mood-anxiety-dissociative disorders.

Disturbed mental imagery of affected body-parts in patients with hysterical conversion paraplegia correlates with pathological limbic activity

Patients with conversion disorder generally suffer from a severe neurological deficit which cannot be attributed to a structural neurological damage. In two patients with acute conversion paraplegia, investigation with functional magnetic resonance imaging (fMRI) showed that the insular cortex, a limbic-related cortex involved in body-representation and subjective emotional experience, was activated not only during attempt to move the paralytic body-parts, but also during mental imagery of their movements. In addition, mental rotation of affected body-parts was found to be disturbed, as compared to unaffected body parts or external objects. fMRI during mental rotation of the paralytic body-part showed an activation of another limbic related region, the anterior cingulate cortex. These data suggest that conversion paraplegia is associated with pathological activity in limbic structures involved in body representation and a deficit in mental processing of the affected body-parts.

Brain circuits implicated in psychogenic paralysis in conversion disorders and hypnosis

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.

Unawareness of deficits in ischemic injury: role of the cingulate cortex

Reduced awareness of illness is a well-known phenomenon that has been studied in patients with vascular disease, but the precise nature of their executive dysfunction is an intriguing question that still has to be resolved. It would be particularly interesting to study patients with reduced awareness of disease possibly related to vascular lesions of the prefrontal cortex. Due to the clinical importance of the case, here we present a patient with a selective right anterior cingulate ischemic injury and impaired awareness of deficits. We suggest that the cingulo-frontal area dysfunction may represent one of the corresponding neurobiological substrates of his persistent unawareness, which has not yet been evaluated in the literature on patients with acquired brain injury (ABI).

Latency to first psychogenic nonepileptic seizure upon admission to inpatient EEG monitoring: evidence for semiological differences

Two hundred sixteen consecutive patients diagnosed with psychogenic nonepileptic seizures (PNES) admitted to the epilepsy monitoring unit at our institution over a 4.5-year period were retrospectively identified. PNES were classified into four semiological subcategories: major motor (n=123), minor motor (n=38), akinetic (n=32), and subjective/experiential (n=23). The median latency to first PNES for the entire population was 7 hours (range: <1 to 207 hours), confirming previous observations that the latency to first PNES on admission is often <24 hours. The novel observation is that latency to first PNES was dependent on type. The median latency to first PNES was significantly prolonged in both the minor motor (median=21 hours) and subjective/experiential (median=22 hours) groups as compared with the major motor (median=5 hours) and akinetic (median=4 hours) groups. Thus, patients with one of these two subtypes may require longer admissions to capture the event of interest and confirm the diagnosis.