Differentiation of Progressive Supranuclear Palsy: clinical, imaging and laboratory tools

Liscic RM, Srulijes K, Groger A, Maetzler W, Berg D. Differentiation€of Progressive Supranuclear Palsy: clinical, imaging and laboratorytools.Acta Neurol Scand: 2013: 127: 362–370.© 2013 John Wiley & Sons A/S.Progressive supranuclear palsy (PSP) is the most common atypicalparkinsonian syndrome comprising two main clinical subtypes:Richardson’s syndrome (RS), characterized by prominent posturalinstability, supranuclear vertical gaze palsy and frontal dysfunction;and PSP-parkinsonism (PSP-P) which is characterized by anasymmetric onset, tremor and moderate initial therapeutic response tolevodopa. The early clinical features of PSP-P are often difficult todiscern from idiopathic Parkinson’s disease (PD), and other atypicalparkinsonian disorders, including multiple system atrophy (MSA) andcorticobasal syndrome (CBS). In addition, rare PSP subtypes may beoverlooked or misdiagnosed if there are atypical features present. Thedifferentiation between atypical parkinsonian disorders and PD isimportant because the prognoses are different, and there are differentresponses to therapy. Structural and functional imaging, althoughcurrently of limited diagnostic value for individual use in earlydisease, may contribute valuable information in the differentialdiagnosis of PSP. A growing body of evidence shows the importanceof CSF biomarkers in distinguishing between atypical parkinsoniandisorders particularly early in their course when disease-modifyingtherapies are becoming available. However, specific diagnostic CSFbiomarkers have yet to be identified. In the absence of reliabledisease-specific markers, we provide an update of the recent literatureon the assessment of clinical symptoms, pathology, neuroimaging andbiofluid markers that might help to distinguish between theseoverlapping conditions early in the course of the disease.