In vivo comparison of Richardson's syndrome and progressive supranuclear palsy-parkinsonism

Richardson's syndrome (RS) and progressive supranuclear palsy-parkinsonism (PSP-P) are the most common subtypes of PSP. Post-mortem data suggests that the clinical presentation of the two subtypes differs especially in the first 2 years of disease and then converges. This hypothesis has, to our knowledge, never been confirmed in a living cohort. Medical history was used to define subtypes retrospectively in 23 consecutive PSP patients from our outpatient clinic specialized in movement disorders. 14 patients suffered from RS, and 9 from PSP-P. Using a prospective cross-sectional approach, clinical, cognitive, behavioral, speech and biochemical (cerebrospinal fluid tau levels) features were compared. RS patients showed shorter time from disease onset to diagnosis and more neuropsychological and neurobehavioral deficits than PSP-P patients, but differed not significantly with regard to clinical and biochemical features. RS and PSP-P show considerable symptoms overlap during the disease course when using routine assessments, with persisting differences regarding non-motor symptoms. Shorter disease duration of the comparably affected RS patients indicates that this subtype has an accelerated disease progression at early disease stages.