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

Posterior cingulate cortex hyperactivity in conversion disorder: a PET/MRI study

Introduction

Several neuroimaging studies have been conducted to demonstrate the specific structural and functional brain correlations of conversion disorder. Although the findings of neuroimaging studies are not consistent, when evaluated as a whole, they suggest the presence of significant brain abnormalities. The aim of this study is to investigate brain metabolic activity through F-18 fluorodeoxyglucose PET/MRI in order to shed light on the neural correlates of conversion disorder.

Methods

20 patients diagnosed with conversion disorder were included in the study. Hamilton Depression and Anxiety Rating Scales, Somatosensory Amplification Scale and Somatoform Dissociation Scale were administered. Then, brain F-18 FDG-PET/MRI was performed..

Results

Hypermetabolism was found in posterior cingulate R, while glucose metabolisms of other brain regions were observed to be within the normal limits. When compared with the control group, statistically significant differences in z-scores were observed among all brain regions except for parietal superior R and cerebellum. No correlation was observed between the metabolisms of the left ACC and left medial PFC; left ACC and left temporal lateral cortex; cerebellum and left parietal inferior cortex despite the presence of positive correlations between these regions in the opposite hemisphere.

Discussion

Results of the study suggest a potential involvement of the DMN which is associated with arousal and self-referential processing as well as regions associated with motor intention and self-agency.

Association between brain metabolism and clinical course of motor functional neurological disorders

Features of resting brain metabolism in motor functional neurological disorder are poorly characterized. This study aimed to investigate the alterations of resting brain metabolism in a cohort of patients experiencing a first episode of motor functional neurological disorder with recent symptom onset, and their association with persistent disability after 3 months. Patients eligible for inclusion were diagnosed with first episode of motor functional neurological disorder, were free from bipolar disorder, substance use disorder, schizophrenia, psychogenic non-epileptic seizure or any chronic or acute organic neurological disorder. Exclusion criteria included current suicidal ideation, antipsychotic intake and previous history of functional neurological disorder. Nineteen patients were recruited in Psychiatry and Neurology departments from 2 hospitals. Resting brain metabolism measured with 18F-fluorodeoxyglucose positron emission computed tomography at baseline and 3 months was compared to 23 controls without neurological impairment. Disability was scored using Expanded Disability Status Scale and National Institutes of Health Stroke Scale score at baseline and 3 months. Correlations were calculated with Spearman correlation coefficient. Hypometabolism was found at baseline in bilateral frontal regions in patients versus controls, disappearing by 3 months. The patients with Expanded Disability Status Scale score improvement showed greater resting state activity of prefrontal dorsolateral cortex, right orbito-frontal cortex and bilateral frontopolar metabolism at 3 months versus other patients. The resting state metabolism of the right subgenual anterior cingular cortex at baseline was negatively correlated with improvement of motor disability (measured with Expanded Disability Status Scale) between inclusion and 3 months (r=-0.75, p = 0.0018) and with change in motor symptoms assessed with the National Institutes of Health Stroke Scale (r=-0.81, p= 0.0005). The resting state metabolism of the left subgenual anterior cingular cortex at baseline was negatively correlated with improvement in Expanded Disability Status Scale and National Institutes of Health Stroke Scale scores between inclusion and 3 months (r= -0.65, p = 0.01 and r= -0.75, p = 0.0021, respectively). The negative association between the brain metabolism of the right subgenual anterior cingular cortex at baseline and change in National Institutes of Health Stroke Scale score remained significant (r=-0.81, p= 0.0414) after correction for multiple comparisons. Our findings suggest the existence of metabolic "state markers" associated with motor disability and that brain markers are associated with motor recovery in functional neurological disorder patients.

Neuroimaging in Functional Neurological Disorder: State of the Field and Research Agenda

Functional neurological disorder (FND) was of great interest to early clinical neuroscience leaders. During the 20th century, neurology and psychiatry grew apart - leaving FND a borderland condition. Fortunately, a renaissance has occurred in the last two decades, fostered by increased recognition that FND is prevalent and diagnosed using "rule-in" examination signs. The parallel use of scientific tools to bridge brain structure - function relationships has helped refine an integrated biopsychosocial framework through which to conceptualize FND. In particular, a growing number of quality neuroimaging studies using a variety of methodologies have shed light on the emerging pathophysiology of FND. This renewed scientific interest has occurred in parallel with enhanced interdisciplinary collaborations, as illustrated by new care models combining psychological and physical therapies and the creation of a new multidisciplinary FND society supporting knowledge dissemination in the field. Within this context, this article summarizes the output of the first International FND Neuroimaging Workgroup meeting, held virtually, on June 17th, 2020 to appraise the state of neuroimaging research in the field and to catalyze large-scale collaborations. We first briefly summarize neural circuit models of FND, and then detail the research approaches used to date in FND within core content areas: cohort characterization; control group considerations; task-based functional neuroimaging; resting-state networks; structural neuroimaging; biomarkers of symptom severity and risk of illness; and predictors of treatment response and prognosis. Lastly, we outline a neuroimaging-focused research agenda to elucidate the pathophysiology of FND and aid the development of novel biologically and psychologically-informed treatments.