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

• A. Resting tremor; Rigidity; Bradykinesia; Postural instability
• B. Tremor at rest; Ataxia; Hyperreflexia; Babinski sign
• C. Chorea; Athetosis; Dystonia; Myoclonus
• D. Numbness; Tingling; Pain; Weakness

Answer: (A)

The main concept here is recognizing the classic motor syndrome of Parkinson's disease. The four cardinal signs are resting tremor, rigidity, bradykinesia, and postural instability. Resting tremor appears when the limb is at rest and is often described as a pill-rolling tremor; it tends to diminish with purposeful movement. Rigidity is increased resistance to passive movement in any direction, sometimes felt as a cogwheel-like resistance. Bradykinesia is a slowness of initiating and carrying out movements, leading to small, slow steps and a masked facial expression. Postural instability refers to impaired balance and a tendency to fall, usually emerging as the disease progresses and can be tested with a pull test. The other options mix signs from other neurological problems, such as cerebellar or upper motor neuron involvement, hyperkinetic movement disorders, or neuropathic symptoms, which are not the characteristic four features of Parkinson’s disease.