We look at the diagnosis of Parkinson's disease as a three-step process.
Step 1: Identify the presence of parkinsonism.
Parkinsonism is a clinical syndrome defined by the presence of the following symptoms:
- Bradykinesia (slowness of movement)
- Rigidity or stiffness of the limbs
- Postural Instability (stooped, slumped posture) or loss of balance
- Resting Tremor (especially a pattern called pill rolling)
- Tremor due to the tremor's resemblance to this action)
The presence of two of these five cardinal features of the syndrome is required to make the diagnosis of parkinsonism.
Step 2: Identify the cause of parkinsonism.
Parkinson's disease is responsible for 75 percent of all cases of parkinsonism.
Other causes include:
- Medications: long-term use of certain drugs can induce symptoms similar to Parkinson's disease
- Infections: certain viral infections that cause the brain to swell and result in Parkinson's-like symptoms
- Structural or vascular lesions: tumor, stroke, hydrocephalus
- Other degenerative disorders: Progressive Supranuclear Palsy (PSP), Multiple System Atrophy (MSA)
Step 3: Prove that the diagnosis is accurate and correct.
Parkinson's Disease can be difficult to diagnose and the best ways to tell if the diagnosis is correct are:
- Positive response to treatment with levodopa (Sinemat®)
- No response or short-lived response to treatment: parkinsonism caused by other degenerative conditions usually does not respond to treatment.
- PET scan to confirm or rule out the diagnosis of Parkinson's.