Diagnosis	Historical features	Signs/symptoms	Radiographic finding	Comments
Idiopathic Parkinson’s disease	Difficulty with tasks, rigidity, tremor	SeeTable 1	No specific CT or MRI findings	—
Drug-induced parkinsonism	Previous use of a causative drug such as an antipsychotic, reserpine (Serpalan), or metoclopramide (Reglan)	Tremor, rigidity, bradykinesia; often bilateral symptoms	Normal	May persist for up to one year after discontinuation of the drug
Vascular parkinsonism	Stepwise progression; CVA or TIA, comorbid cardiovascular disease	Fixed deficits from previous events	Lesions in white matter with or without basal ganglia5	Common because of the prevalence of cerebrovascular disease5
Essential tremor	History in multiple family members, little evolution5	Tremor often is action-based; absence of extrapyramidal symptoms (except possible mild rigidity); no response to levodopa5; tremor often is bilateral and can be attenuated by alcohol6	SPECT shows normal dopaminergic system5	Common5
Normal-pressure hydrocephalus	Ataxia, dementia, urinary incontinence	Ataxic gait, change in mental status	CT or MRI shows hydrocephalus5	Distinctive clinical features
Progressive supranuclear palsy	Onset after 40 years of age; frequent falls5	Vertical gaze paralysis (or slowed vertical saccadic movements); marked postural instability (increased fall risk within the first year of disease)5; resting tremor (rare)6; nuchal dystonia; normal olfaction7	MRI shows mesencephalon-brainstem atrophy involving the superior colliculi5	—
Multiple system atrophy (e.g., Shy Drager syndrome, olivopontocerebellar atrophy, nigrostriatal degeneration)	Autonomic and urinary dysfunction, parkinsonism with poor levodopa response, cerebellar dysfunction5	Resting tremor (rare), transient response to levodopa (25 percent of patients)6; possible mild impaired olfaction but less severe than Parkinson’s disease8	MRI shows nigrostriatal degeneration with gliosis in the lateral putamen with hyperintense proton density bands and hypointense bands in the T2 images5	Decreased sphincter EMG results; changes in urodynamic and sympathocutaneous testing; altered cardiovascular responses5
Corticobasal degeneration	Cortical and cognitive impairment with involuntary movements5	Apraxia, aphasia, sensory disorders, positive Babinski test, asymmetrical parkinsonism without impaired deambulation (difficulty in stopping gait), myoclonus, dystonia5	MRI shows asymmetric atrophy of frontal and parietal regions, there may be atrophy of basal ganglia and/or corpus callosum; PET shows decreased glucose metabolism in frontoparietal cortex, thalamus, and basal ganglia	Commonly Underdiagnosed because of its heterogeneity5
Dementia with Lewy bodies	Cognitive impairment, hallucinations, episodes of delirium, parkinsonism5	Impaired attention and visuospatial abilities, increased falls, episodes of syncope5	PET shows low glucose metabolism in cortex5	Marked intolerance to neuroleptic drugs5