Pathophysiology

In PD, there is decreased stimulation of the motor cortex by the basal ganglia. This reflects reduced dopaminergic activity in the basal ganglia.

The basal ganglia provide a functional link between the association cortex of the forebrain (especially the frontal and parietal areas) and the motor cortex.

The basal ganglia is an essential component in the planning and execution of voluntary movement.

However, and although less obvious, the patient is often as much disabled by the associated features of autonomic dysfunction and cognitive impairment that occur with disease progression.

Patients who have only the motor features of the disease are said to exhibit Parkinsonism. There is usually an identifiable cause.

This contrasts to patients with PD who have, or subsequently develop, autonomic and cognitive changes. Parkinson’s disease itself is idiopathic.

Fig 1 Basal ganglia