What is the primary movement disorder characterized by festinating gait and postural instability?

The primary movement disorder characterized by festinating gait and postural instability is Parkinson's disease. This condition is marked by a combination of motor symptoms that result from the degeneration of dopaminergic neurons in the substantia nigra, a critical area of the brain involved in movement control.

Festinating gait is a specific type of gait seen in Parkinson's, where the individual moves in short, hurried steps that appear to accelerate as they walk. This is often accompanied by difficulty in starting movements, making turns, and stopping, which are characteristic motor symptoms of the disorder. Postural instability refers to impaired balance and the inability to maintain an upright stance, leading to an increased risk of falls. Both of these features are directly linked to the underlying pathophysiology of Parkinson's disease, where the loss of dopamine leads to dysfunction in the basal ganglia and results in the hallmark signs of the disorder.

Other options may cover conditions that could present with different types of motor dysfunction or cognitive impairment, but they do not specifically encompass the classic motor symptoms associated with Parkinson's disease, like festinating gait and postural instability.