Differential Diagnosis for Parkinson's Disease (PD) vs. Parkinsonism (Parkinson's Syndrome)
Single most likely diagnosis
- Idiopathic Parkinson's Disease (PD): Characterized by asymmetrical symptoms (C), which is a hallmark feature distinguishing it from other forms of parkinsonism. Idiopathic PD typically presents with a combination of tremors, rigidity, bradykinesia, and postural instability, with symptoms often starting unilaterally.
Other Likely diagnoses
- Vascular Parkinsonism: Often presents with a more symmetrical onset (A) and may have a history of vascular risk factors or evidence of small vessel disease on imaging. Early onset of postural instability (B) can also be a feature.
- Drug-induced Parkinsonism: Symptoms can be symmetrical (A) and are directly related to the use of certain medications, such as antipsychotics or antiemetics. The history of medication use is crucial for diagnosis.
- Normal Pressure Hydrocephalus (NPH): Presents with the classic triad of gait disturbance, dementia, and urinary incontinence. While not typically considered a primary parkinsonian syndrome, it can mimic some features of parkinsonism, including gait instability.
Do Not Miss diagnoses
- Creutzfeldt-Jakob Disease (CJD): A rare, rapidly progressive neurological disorder that can present with parkinsonian features, myoclonus, and dementia. It is crucial to consider CJD due to its rapid progression and fatal outcome.
- Wilson's Disease: An inherited disorder of copper metabolism that can present with neurological symptoms, including parkinsonism, tremors, and psychiatric disturbances. Early diagnosis is critical as treatment can prevent further progression.
Rare diagnoses
- Progressive Supranuclear Palsy (PSP): Characterized by prominent postural instability and falls early in the disease course (B), along with supranuclear vertical gaze palsy. It is less common than idiopathic PD and has a distinct clinical presentation.
- Multiple System Atrophy (MSA): Presents with a combination of parkinsonian features, autonomic dysfunction, and cerebellar ataxia. It can be difficult to distinguish from idiopathic PD, especially in the early stages.
- Corticobasal Degeneration (CBD): A rare neurodegenerative disorder characterized by asymmetrical parkinsonism, dystonia, and myoclonus, often with a pronounced alien limb phenomenon. It is less common and can be challenging to diagnose.