The differential diagnosis of parkinsonism (tremor, rigidity, bradykinesia, and gait difficulty/postural instability) is broad and includes two neurodegenerative conditions that exist on a clinicopathologic spectrum: progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). Early in their clinical course, PSP and CBS may be difficult to distinguish from Parkinson disease and several other illnesses, but it is crucial to do so because of implications for management and prognosis.
Early accurate diagnosis of PSP and CBS remains a challenge because of heterogeneity in presenting symptoms and high frequency of coexisting pathologies (especially Alzheimer disease and vascular disease). It is increasingly recognized that patients with PSP, CBS, and other parkinsonian disorders require multidisciplinary care for optimal outcomes. With the recent proliferation of biomarker studies and therapeutic trials for tauopathies, there is growing hope that better treatments for PSP and CBS are on the horizon.
Although PSP and CBS currently lack disease-modifying therapies, it is important to diagnose them as early as possible so that the patient can benefit from the many available symptomatic therapies, support groups, and a growing number of clinical trials.