Many of the symptoms of Parkinson's disease (PD) involve motor control – the ability to control your muscles and movement. The four primary categories of PD motor symptoms are:
Tremor – Involuntary, rhythmic shaking of a limb, head, or entire body
Tremor is the most recognized symptom of PD and often starts with an occasional tremor in one finger that eventually spreads to the whole arm. Tremor is present when the limb is at rest or held up in an unsupported position; it disappears briefly during movement. The tremor may affect only one part or side of the body, especially in the early stages of the disease. Not everyone with PD has tremor.
Rigidity – Stiffness or inflexibility of the limbs or joints
The muscle rigidity experienced in PD often begins in the legs and neck. Rigidity or resistance to movement affects most patients. The muscles become tense and contracted, and some patients may feel pain or stiffness.
Bradykinesia/Akinesia – Slowness of movement/Absence of movement
Slowness of movement or bradykinesia is one of the classic symptoms of PD. Over time, a person with PD may develop a stooped posture and a slow, shuffling walk. They eventually also may lose their ability to start and keep moving. Their gait – the way they walk — can be erratic and unsteady and cause them to fall. After a number of years, their muscles may not move at all. This is called akinesia or freezing.
Postural Instability – Impaired balance and coordination
A person with postural instability may have a stooped position: the head is bowed and the shoulders drooped. They may develop a forward or backward lean. Some people with postural instability have many falls that cause injuries. People with a backward lean have a tendency to step backwards, which is known as retropulsion.