Atypical progressive supranuclear palsy syndrome is a rare late-onset neurodegenerative disease that does not follow the typical pattern of progressive supranuclear palsy (PSP). It is characterized by PSP-tau pathology and can manifest in various ways, including PSP with predominant Parkinsonism, progressive gait freezing, corticobasal syndrome, speech/language disorder, frontal presentation, ocular motor dysfunction, and postural instability. Symptoms can affect movement, speech, and cognition. PSP is linked to 4-repeat tau pathology, leading to balance issues, slow movement, eye movement difficulties, and cognitive decline. It can be mistaken for other neurodegenerative diseases and is the second most common tauopathy after Alzheimer's disease. The cause involves tau protein accumulation in the brain, and treatments like levodopa and amantadine may help manage symptoms.