Conversion disorder is characterized by the occurrence of certain signs or symptoms that are clearly inconsistent with what is known about anatomy and pathophysiology. For example, the patient may complain of blindness, yet cortical visual evoked potentials are normal. Or a patient may complain of complete anesthesia of the left upper extremity and go on to describe the boundary of the anesthesia as being a clear-cut line encircling the elbow.
Other common complaints include hemiplegia, deafness, and seizures. On close inspection the specific symptomatology in each case corresponds with the patient’s particular conception of how an illness might manifest itself.
Take for example a patient who complains of such unsteadiness that walking is impossible; the patient’s conception of the malady, however, simply does not encompass the symptomatology evident at bedside examination that the physician’s knowledge of pathophysiology would predict.
Thus, although the patient stumbles and lurches in the attempt to cross from chair to the bed, in bed there is no truncal ataxia and no deficiency on finger-to-nose or heel-to-knee-to-shin testing.
Patients who find themselves with such symptoms, however, are not to be confused with malingerers or those with factitious illness. Patients who suffer conversion symptoms do not intentionally feign such symptoms, as malingerers do; they experience them as genuine, and their distress over them may be as genuine as that of the patient whose unsteadiness is produced by a midline cerebellar tumor.
A synonym for conversion disorder is “hysterical neurosis, conversion type.” Both terms are to a degree unfortunate. The term “conversion” has its roots in psychoanalysis and connotes a specific etiologic theory that has not been substantiated. “Hysterical,” though an ancient term, has so many different meanings and is such a pejorative term that it might best be allowed to rest in peace.