Towards a Neuropsychiatry of Conversive Hysteria

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Abstract
In their current version, conversive symptoms were first conceptualised at the turn of the century, and from the start both neuropsychiatric and psychodynamic models became available for their explanation. Apart from theoretical and technical limitations, the early neuropsychiatric models were hampered by the fact that the definition of conversive symptom was equivocal and by exclusion. The development of important research techniques, together with an emphasis on the single case study, have led to important advances in the field and for the first time, testable hypotheses can be put forward to explain conversive disorders. Thus, neurophysiological evidence suggests that inhibitory mechanisms may be at play at a high level (cognitive stage) of sensory/motor processing leading to an exclusion from awareness of information on the ongoing status of sensory and/or motor function. Neuroimaging studies, in turn, suggest that prefrontal structures may be the more likely substrate for such inhibitory mechanisms. This putative alteration of attention and awareness should be understood in terms of the current neuropsychological view that residual unconscious cognitive processing goes on in the absence of awareness. It is also suggested that the fact that the right inferior parietal cortex (a crucial structure in the mediation of awareness), unlike primary sensory cortices, is independent from topological constraints, may explain the lack of anatomical constraint observed in conversion symptoms. Circumstantial evidence for the involvement of brain attentional system in conversion hysteria is also provided by lateralisation studies, which show that, as in parietal neglect, conversion symptoms also tend to lateralise to the left side regardless of hand dominance.