Recently, the news has highlighted an odd phenomenon plaguing at least 15 teenage girls in a community in upstate New York. The girls began demonstrating spasms, tics and seizures and the condition appeared to be contagious. After rigorous amounts of diagnostic testing, experts found …. nothing. The conclusion only conclusion that could be made was that these girls were demonstrating what is known as a conversion disorder, or a disorder in which one exhibits physical symptoms without physical cause. The DSM-IV classifies it as a psychiatric disorder, formerly known as hysteria.
A recent article published in Brain highlighted why this disorder may occur. The authors of this study conducted a functional magnetic resonance imaging study and compared functional brain connectivity and reaction to fearful, happy and neutral face stimuli. A post hox anaylsis revealed that:
- healthy subjects had greater right amygdala activity to fearful vs. neutral stimuli as compared to happy vs. neutral stimuli. There was no major differences in patients with conversion disorder.
- individuals with conversion disorder, had greater right amygdala activity to happy stimuli than healthy subjects. This suggests that there is possible imparied amygdala habituation in individuals with conversion disorders.
- individuals with conversion disorder had greater functional connectivity between the right amygdala and right supplementary motor area
- these occured more frequently in women
- the most common abnormality was fixed dystonia
- In 26% of cases, a nerve injury was identified
- 1/3 were thought to also have CRPS
- 15% had been diagnosed with a “psychogenic movement disorder” which is more associated with fixed dysotnia and tremor
Voon V, Brezing C, et al. Emotional stimuli and motor conversion disorder. Brain 2010: 133; 1526-1536.
Rooijen DE, Geraedts, et al. Peripheral trauma and movement disorders: a systematic review of reported cases. J Neurol Neurosurg Psychiatry 2011;82: 892-898.
Brown, RJ, Cardena, E, et al. Should Conversion Disorder Be Reclassified as a Dissociative Disorder in DSM V?. Psychosomatics 2007: 48; 369–378.