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

Markus Boeckle,Christoph Pieh,Gregor Liegl,Robert Jank

doi:10.1186/s12888-016-0890-x

Abstract

BackgroundConversion 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).MethodsA 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.ResultsPatients 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.ConclusionsNeuronal 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.

Highlights

Conversion Disorders (CD) are prevalent functional disorders
The inclusion criteria were defined as the following: 1) paper written in English; 2) investigating human adults; 3) has to be primary research; 4) study has to use one of the listed imaging methods (PET, MRI, single-photon emission computed tomography (SPECT)); 5) studies investigated patients with CD or synonymous disorder according to DSM-IV, DSM-V, or ICD10 excluding studies using hypnosis or feigning behaviour as alternative study population for CD
After analysing the full texts, we reported all studies using neuroimaging and CD or dissociative disorders as the classification of CD in ICD and DSM differ according to this point

Summary

Introduction

The pathogenesis is still not completely understood, an interaction of genetic, neurobiological, and psychosocial factors is quite likely. Similar to other psychiatric disorders an interrelation of Boeckle et al BMC Psychiatry (2016) 16:195 genetic, neurobiological, and psychosocial factors is highly plausible. Dissociative symptoms are reported as a side effect of medication [9] and associated with endocrinological disorders [10], which points to neurobiological influences [7, 11]. Psychosocial influences are assumed in the pathogenesis of dissociative disorders, which are according to ICD-10 [12] closely related to CD. There is rising evidence that dissociative symptoms are associated with trauma, as depersonalization and derealisation are quintessential responses to acute trauma [14] and dissociative symptoms often occur in patients with post-traumatic stress disorder (PTSD) [15]

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