Atypical parkinsonisms are conditions in which an individual experiences some of the signs and symptoms of Parkinson's disease (PD) -- tremor, slowness, rigidity (stiffness), and/or walking and balance problems -- but does not have PD. Atypical parkinsonism can be due to certain medications (some anti-nausea and antipsychotic drugs), other brain disorders (repeated head injury or multiple small strokes) or neurodegenerative diseases.
The neurodegenerative diseases, which cause damage or death of brain cells, include corticobasal degeneration, Lewy body dementia, multiple system atrophy and progressive supranuclear palsy. These conditions are often referred to as "Parkinson's plus" because they mimic PD but have extra associated symptoms (the "plus"). They can be misdiagnosed as Parkinson's disease because no blood or imaging test can, on its own, make a definitive diagnosis. (As with PD, the diagnosis is based on a person's medical history and physical examination.) Early in the course, people with Parkinson's plus syndromes also may get some benefit from levodopa, the drug most commonly used to treat PD. A poor response to levodopa, development of additional symptoms and more rapid progression of disease may eventually differentiate Parkinson's plus from PD, although it can take years for these differences to emerge. As with PD, no disease-modifying therapy has been discovered for any of the neurodegenerative atypical parkinsonisms so treatment is symptomatic and supportive.
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