Progressive supranuclear palsy (PSP) is a neurodegenerative tauopathy characterized by accumulation of abnormally hyperphosphorylated tau protein in neurons and glial cells of the basal ganglia, brainstem, and frontal cortex. Unlike Parkinson disease, PSP involves 4-repeat (4R) tau isoforms forming neurofibrillary tangles in specific brain regions, leading to its distinctive clinical features. The hallmark feature is supranuclear vertical gaze palsy — an inability to voluntarily look up or down (initially downward), while reflexive eye movements (oculocephalic reflex/doll's eyes) are preserved, indicating the pathology is 'above' (supranuclear to) the brainstem gaze centers. This distinguishes PSP from nuclear or infranuclear gaze palsies. Other features include early postural instability with backward falls (unlike Parkinson disease, which causes forward falls), axial rigidity greater than limb rigidity, pseudobulbar affect (involuntary laughing or crying), frontal lobe dysfunction (personality changes, impulsivity, apathy), dysphagia (aspiration pneumonia is a leading cause of death), and a characteristic 'wide-eyed surprised stare.' Unlike Parkinson disease, PSP shows poor response to levodopa, symmetric onset, absence of rest tremor, and rapid progression (median survival 5-7 years from symptom onset). The nurse focuses on fall prevention...