Akinesia

The loss or impairment of the ability to initiate voluntary movement, distinct from muscle weakness or paralysis. In Parkinson's Disease, akinesia manifests as difficulty starting movements, reduced spontaneous movements like blinking or arm swing while walking, and a mask-like facial expression. Akinesia is related to but distinct from bradykinesia (slow movement)—a person with akinesia may be unable to begin a movement at all, while bradykinesia describes movements that start but proceed slowly. For assistive technology design, akinesia means users may need extended timeouts and should not face penalties for slow response initiation.