Functional neuroimaging of conversion disorder: the role of ancillary activation.
BACKGROUND
Previous functional neuroimaging studies investigating the neuroanatomy of conversion disorder have yielded inconsistent results that may be attributed to small sample sizes and disparate methodologies. The objective of this study was to better define the functional neuroanatomical correlates of conversion disorder.


METHODS
Ten subjects meeting clinical criteria for unilateral sensory conversion disorder underwent fMRI during which a vibrotactile stimulus was applied to anesthetic and sensate areas. A block design was used with 4 s of stimulation followed by 26 s of rest, the pattern repeated 10 times. Event-related group averages of the BOLD response were compared between conditions.


RESULTS
All subjects were right-handed females, with a mean age of 41. Group analyses revealed 10 areas that had significantly greater activation (p < .05) when stimulation was applied to the anesthetic body part compared to the contralateral sensate mirror region. They included right paralimbic cortices (anterior cingulate cortex and insula), right temporoparietal junction (angular gyrus and inferior parietal lobule), bilateral dorsolateral prefrontal cortex (middle frontal gyri), right orbital frontal cortex (superior frontal gyrus), right caudate, right ventral-anterior thalamus and left angular gyrus. There was a trend for activation of the somatosensory cortex contralateral to the anesthetic region to be decreased relative to the sensate side.


CONCLUSIONS
Sensory conversion symptoms are associated with a pattern of abnormal cerebral activation comprising neural networks implicated in emotional processing and sensory integration. Further study of the roles and potential interplay of these networks may provide a basis for an underlying psychobiological mechanism of conversion disorder.
Department of Neurology, University of Toronto, Toronto, Ontario M4N 3M5, Canada.
Matthew J
MJ
Burke
Department of Psychiatry, University of Toronto, Toronto, Ontario M4N 3M5, Canada ; Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Room FG16, Toronto, Ontario M4N 3M5, Canada.
Omar
O
Ghaffar
Department of Kinesiology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada.
W Richard
WR
Staines
Department of Psychiatry, University of Toronto, Toronto, Ontario M4N 3M5, Canada ; Toronto Western Hospital, 399 Bathurst Street, Room 7M-415, Toronto, Ontario M5T 2S8, Canada.
Jonathan
J
Downar
Department of Psychiatry, University of Toronto, Toronto, Ontario M4N 3M5, Canada ; Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Room FG16, Toronto, Ontario M4N 3M5, Canada.
Anthony
A
Feinstein
D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003291:Conversion Disorder / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged
Conversion disorder; Functional neuroimaging; Sensory