La belle indifférence revisited: a case report on progressive supranuclear palsy misdiagnosed as conversion disorder

BACKGROUND Since the advent of computed tomography and magnetic resonance imaging scans, neurological disorders have less often been falsely labeled as conversion disorder (CD). However, misdiagnosis of a neurological disorder as CD still occurs, especially in cases with insidious onset. Misinterpretation of la belle indifférence may contribute to such misdiagnosis. Here, we describe a case of progressive supranuclear palsy/Richardson's syndrome (PSPS) misdiagnosed as a case of CD. CASE A 62-year-old woman consulted two different neurologists in 2012 because of falling spells since 2009 and was diagnosed with CD. She was referred to the Clinical Center of Excellence for Body, Mind, and Health for treatment of CD. After neurological examination, blood tests, and psychiatric examination, in which la belle indifférence and a history of incest were found, CD was confirmed. However, despite treatment for CD, the patient's physical symptoms deteriorated over a year. After repeated physical and psychiatric examinations, neurocognitive assessment, and consultation with a third neurologist because of suspicion of neurological disease, the patient was diagnosed with PSPS. CONCLUSION La belle indifférence may be a psychological sign in the context of CD, but it may also be an expression of lack of mimic due to Parkinsonism or of eye movement disorder in the context of neurological illness. A diagnosis of CD should not be considered definitive if no improvement occurs in terms of physical, mental, and cognitive symptoms despite appropriate therapy. In case of deterioration, neurological reexamination and reinterpretation of la belle indifférence should be considered.