What are typical postural control deficits seen in Parkinson's disease during quiet stance and movement initiation?

• A. Decreased sway and improved axial mobility.
• B. Increased sway, reduced axial/trunk mobility, delayed or diminished anticipatory postural adjustments, bradykinesia, and impaired stepping leading to higher fall risk.
• C. No deficits in quiet stance.
• D. Improved stepping with disease.

Answer: (B)

Parkinson's disease disrupts postural control in quiet stance and at movement initiation. In quiet stance, people with PD typically exhibit increased postural sway and reduced axial/trunk mobility due to rigidity and altered motor control, making small perturbations harder to counter. When initiating movement, anticipatory postural adjustments are delayed or reduced in amplitude, bradykinesia slows the onset of movement, and stepping is often impaired (short, hesitant steps), all of which together raise fall risk. These features—more sway, limited trunk mobility, delayed or diminished APAs, slowed movement, and compromised stepping—best capture the typical postural control deficits seen in PD.