Which set lists the four cardinal signs of Parkinson's disease?

• A. Bradykinesia, Resting Tremor, Rigidity, Postural Instability
• B. Tremor at Rest, Apathy, Rigidity, Seizures
• C. Bradykinesia, Spasticity, Hyperreflexia, Tremor
• D. Postural Instability, Seizures, Tremor, Memory Impairment

Answer: (A)

Parkinson's disease is defined by four hallmark motor features. These are bradykinesia (slowness of movement), resting tremor (tremor when the limb is not being used, which diminishes with purposeful movement), rigidity (increased resistance to passive movement, often felt as cogwheel-like rigidity), and postural instability (impaired balance leading to a higher risk of falls). The set that lists these four signs best captures the classic presentation, reflecting the core motor syndrome used to recognize Parkinson's.

Other options include features that are not part of the defining four: apathy, seizures, memory impairment, spasticity, or hyperreflexia are not the characteristic quartet of Parkinson's and point to other disorders or non-motor symptoms that can appear but do not define the disease.