Functional Brain Imaging in a Woman With Spatial Neglect Due to Conversion Disorder FREE

To the Editor: Conversion disorder is a neurological disturbance that cannot be attributed to an organic disease but arises from unconscious psychological stress.¹ Patients most often present with a motor, sensory, or visual deficit. Other cognitive symptoms such as amnesia, aphasia, or pseudodementia may also occur, but to our knowledge, spatial neglect (lateralized deficits in spatial attention typically following right-brain damage²) has not been reported in relation to conversion.¹ We describe a patient who developed a spatial neglect syndrome of conversion origin in whom brain activity was investigated by functional magnetic resonance imaging (fMRI). The patient provided written informed consent for publication of her case, and the study was approved by the ethics committee of Geneva University Hospital.

A 56-year-old right-handed woman came to the hospital emergency department after briefly fainting. She was married with 5 children. She reported experiencing a poor marital relationship for many years but being too dependent on her husband to leave. Shortly after their last child left home, the patient began to develop brief episodes of dizziness and self-described disorientation. One episode occurred on the day of admission and was followed by sudden collapse with transient unresponsiveness but no convulsion.

Neurological examination showed hypoesthesia and weakness of the left arm and leg, sparing the face. Neuropsychological assessment demonstrated left spatial neglect in line-bisection and bell-cancellation tests but no other deficit (testing details available from author). Cerebral MRI, electroencephalogram, and arterial ultrasound findings were normal. Psychiatric interview indicated depressed mood and acute exacerbation of conjugal conflicts. Sensorimotor symptoms disappeared within 5 days, but spatial neglect persisted for more than 20 days and then also remitted. Based on the exclusion of an organic cause and psychiatric evaluation, the patient's deficits were diagnosed as a conversion disorder (consistent with Diagnostic and Statistical Manual of Mental Disorders [Fourth Edition] criteria).

While the patient was experiencing neglect, fMRI was performed during a line-bisection task. The patient was shown premarked lines,³ half correctly centered and half deviated (rightward or leftward), and asked to report whether the bisection mark was placed at the midpoint (testing details available from author). Behavioral performance confirmed neglect signs with more errors for leftward-bisected (72%; 95% confidence interval [CI], 59%-85%) and centrally bisected (96%; 95% CI, 90%-100%) than rightward-bisected lines (20%; 95% CI, 9%-31%). Results from fMRI showed selective activation of the posterior parietal cortex with right predominance when comparing lines with deviated bisection (rightward or leftward) relative to centered bisection, similar to healthy persons performing comparable tasks³ (Figure). These findings indicate that brain systems mediating spatial attention were still differentially recruited by the left and right shifts in attention that were induced by deviated bisection marks, despite the lack of explicit report by the patient. Additional activity was also observed in the anterior cingulate cortex.

The findings of this case, suggesting neglect of conversion origin, indicate that such symptoms may not simply reflect symbolic behavior or beliefs (as postulated by Freud and Breuer¹) but appear to affect cognitive processes that can be selectively disconnected from conscious awareness, as observed for neglect after organic lesions.^1- 2 The fMRI data support this hypothesis by showing preserved activation of parietal cortex (normally recruited by line bisection),³ together with increases in anterior cingulate that might relate to attention,² conflict between instructions and intentions,^1,4 and inhibitory processes specifically related to the production of conversion.⁵

Automatic shifts of attention in both directions (indicating spontaneous and symmetric responses to lateralized stimuli), combined with no shift of attention when judging centrally bisected stimuli, point to involuntary control of attentional processes in the parietal cortex, consistent with impaired access to conscious control. This study highlights the existence of neglect symptoms due to conversion, demonstrates specific functional neuroanatomical correlates, and confirms and extends previous evidence for increased cingulate activity during conversion with other purely motor symptoms.^5- 6