title: Uncovering the etiology of conversion disorder: insights from functional neuroimaging.
abstract: Conversion disorder (CD) is a syndrome of neurological symptoms arising without organic cause, arguably in response to emotional stress, but the exact neural substrates of these symptoms and the underlying mechanisms remain poorly understood with the hunt for a biological basis afoot for centuries. In the past 15 years, novel insights have been gained with the advent of functional neuroimaging studies in patients suffering from CDs in both motor and nonmotor domains. This review summarizes recent functional neuroimaging studies including functional magnetic resonance imaging (fMRI), single photon emission computerized tomography (SPECT), and positron emission tomography (PET) to see whether they bring us closer to understanding the etiology of CD. Convergent functional neuroimaging findings suggest alterations in brain circuits that could point to different mechanisms for manifesting functional neurological symptoms, in contrast with feigning or healthy controls. Abnormalities in emotion processing and in emotion-motor processing suggest a diathesis, while differential reactions to certain stressors implicate a specific response to trauma. No comprehensive theory emerges from these clues, and all results remain preliminary, but functional neuroimaging has at least given grounds for hope that a model for CD may soon be found.
authors.affiliation: Department of Psychiatry, University of Melbourne, Austin Health, Heidelberg, VIC, Australia.
authors.forename: Maryam
authors.initials: M
authors.lastname: Ejareh Dar
authors.affiliation: Department of Psychiatry, University of Melbourne, Austin Health, Heidelberg, VIC, Australia.
authors.forename: Richard Aa
authors.initials: RA
authors.lastname: Kanaan
keywords: conversion disorder; functional neurology; hysteria; mechanisms; neuroimaging
references.citation: Innov Clin Neurosci. 2015 May-Jun;12(5-6):27-33
references.pmid: 26155375
references.citation: Hist Human Sci. 2010;23(2):68-85
references.pmid: 20549878
references.citation: Brain. 2001 Jun;124(Pt 6):1077-90
references.pmid: 11353724
references.citation: Proc Biol Sci. 2010 Aug 22;277(1693):2503-9
references.pmid: 20375048
references.citation: Nat Rev Neurosci. 2008 Nov;9(11):856-69
references.pmid: 18843271
references.citation: Cognition. 1997 Jul;64(1):B1-8
references.pmid: 9342933
references.citation: Neuroimage. 2009 Sep;47(3):1026-37
references.pmid: 19450695
references.citation: Psychol Med. 2004 May;34(4):583-9
references.pmid: 15099413
references.citation: J Neurol Neurosurg Psychiatry. 2012 Mar;83(3):248-50
references.pmid: 22250186
references.citation: Neurophysiol Clin. 2014 Oct;44(4):315-21
references.pmid: 25306072
references.citation: Neuropsychol Rev. 2002 Mar;12(1):31-64
references.pmid: 12090718
references.citation: J Neurol Neurosurg Psychiatry. 2012 Aug;83(8):842-50
references.pmid: 22661497
references.citation: Neuroimage. 2002 Oct;17(2):988-98
references.pmid: 12377172
references.citation: Brain. 2010 May;133(Pt 5):1526-36
references.pmid: 20371508
references.citation: Science. 2009 May 8;324(5928):811-3
references.pmid: 19423830
references.citation: PLoS One. 2011;6(10):e25918
references.pmid: 22039428
references.citation: Arch Gen Psychiatry. 1972 Dec;27(6):771-7
references.pmid: 4637894
references.citation: Brain. 2012 Nov;135(Pt 11):3495-512
references.pmid: 22641838
references.citation: Neurophysiol Clin. 2014 Oct;44(4):339-42
references.pmid: 25306074
references.citation: Cereb Cortex. 2011 Oct;21(10):2394-8
references.pmid: 21368085
references.citation: Epilepsia. 2010 May;51(5):752-9
references.pmid: 19889016
references.citation: Psychosom Med. 2007 Dec;69(9):961-9
references.pmid: 17991812
references.citation: Neuron. 2012 Oct 18;76(2):450-60
references.pmid: 23083745
references.citation: Lancet. 2000 Mar 18;355(9208):986-7
references.pmid: 10768440
references.citation: Biol Psychol. 2015 Jul;109:73-85
references.pmid: 25951783
references.citation: J Med Philos. 1994 Jun;19(3):239-59
references.pmid: 7964210
references.citation: PLoS One. 2013 Apr 23;8(4):e62539
references.pmid: 23626829
references.citation: J Magn Reson Imaging. 2006 Jun;23(6):840-50
references.pmid: 16649207
references.citation: Am J Psychiatry. 1980 Feb;137(2):217-20
references.pmid: 7352579
references.citation: J Neurol Neurosurg Psychiatry. 2015 Oct;86(10 ):1106-12
references.pmid: 25466258
references.citation: Neuropsychologia. 2007 May 15;45(9):2051-8
references.pmid: 17367826
references.citation: Cogn Neuropsychiatry. 1999 Aug;4(3):203-26
references.pmid: 16571507
references.citation: J Neurol Neurosurg Psychiatry. 2011 Nov;82(11):1267-73
references.pmid: 21036784
references.citation: JAMA Psychiatry. 2014 Jan;71(1):52-60
references.pmid: 24258270
references.citation: J Neurol Sci. 2010 Feb 15;289(1-2):155-8
references.pmid: 19733363
references.citation: Neuroimage Clin. 2014 Sep 30;6:333-9
references.pmid: 25379447
references.citation: J Cogn Neurosci. 2006 Jun;18(6):932-48
references.pmid: 16839301
references.citation: Biol Psychiatry. 1995 Jan 15;37(2):134-5
references.pmid: 7536480
references.citation: Curr Opin Psychiatry. 2008 May;21(3):275-80
references.pmid: 18382227
references.citation: Neuropsychologia. 2010 May;48(6):1782-8
references.pmid: 20206641
references.citation: Psychiatry Res. 1998 Sep 28;83(3):163-8
references.pmid: 9849725
references.citation: Neurology. 2010 Jan 19;74(3):223-8
references.pmid: 20083798
references.citation: Harv Rev Psychiatry. 2005 Jan-Feb;13(1):1-13
references.pmid: 15804930
references.citation: PLoS One. 2015 Apr 10;10(4):e0123273
references.pmid: 25859660
references.citation: Psychosom Med. 2007 Feb-Mar;69(2):202-5
references.pmid: 17327215
references.citation: Neuroimage. 2013 Feb 1;66:278-87
references.pmid: 23110885
references.citation: Trends Cogn Sci. 2010 Jan;14(1):16-21
references.pmid: 19969501
references.citation: Science. 2004 Jan 9;303(5655):232-5
references.pmid: 14716015
references.citation: Neurology. 2003 May 13;60(9):1501-7
references.pmid: 12743239
references.citation: Mov Disord. 2011 Aug 15;26(10):1787-8
references.pmid: 21761457
references.citation: Mov Disord. 2011 Nov;26(13):2396-403
references.pmid: 21935985
references.citation: Semin Neurol. 2012 Sep;32(4):421-31
references.pmid: 23361486
references.citation: Lancet. 2000 Apr 8;355(9211):1243-4
references.pmid: 10770312
references.citation: Lancet. 1998 Jun 13;351(9118):1801-4
references.pmid: 9635969
references.citation: Brain. 2013 Mar;136(Pt 3):770-81
references.pmid: 23436503