A 79-year-old woman is brought to the clinic for assessment of frequent falls. There is no loss of consciousness associated with the falls, and she reports no postural change or symptoms prior to the falls. She also describes difficulty in "getting going" when she starts walking and notices that her balance is "not right." Her gait is slow and shuffling on inspection. Which of the following is the most likely finding in a patient with Parkinson disease?

The characteristic triad in Parkinson disease (tremor, rigidity, akinesia) has been expanded to include postural instability. This forms the mnemonic TRAP. Autonomic instability is also common. Findings on examination also include masklike facies, dysarthria, stooped posture, and abnormal gait. The tremor of Parkinson disease is present at rest but diminishes/resolves on active movement. Muscle atrophy, papillary changes, and spontaneous remission are not usual features of Parkinson disease.