Which finding would support a client's diagnosis of Parkinson disease?

• A. Nonintentional tremors
• B. Rigidity to passive movement
• C. Masklike facial expression
• D. Hyperextension of the neck

Answer: (B)

Rigidity to passive movement is a hallmark motor finding in Parkinson disease. In PD, loss of dopaminergic neurons disrupts basal ganglia circuits, leading to increased muscle tone. When a clinician moves a patient’s limb, there is an unmistakable resistance that can feel like a lead-pipe rigidity (sometimes with a cogwheel feel if the resistance fluctuates). This direct sign of increased tone is a classic clue pointing to Parkinson disease.

Resting tremor can occur in PD but can appear in other conditions as well and isn’t as specific on its own. A masklike facial expression is common in PD but is a facial feature rather than a primary motor sign showing the underlyingRigidity. Hyperextension of the neck is not typical for Parkinson disease and points more toward other issues.

So, the presence of rigidity to passive movement most directly reflects the motor changes seen in Parkinson disease and best supports the diagnosis.