It occurs when neurons in a part of the brain called the substantia nigra die or become impaired.

allows smooth, coordinated function of the body's muscles and movement. When ~80% of the dopamine producing cells are damaged, the symptoms of the disease appera.

An "off" episode is a period is a period of time with muscle stiffness, slow movements, and difficulty starting movement.

Primay Signs/Symptoms:

Tremor - seen during resting, usualy worsened by anxiety

Rigidity - arms, legs, trunk and face (mask-like face)

Akinesia/bradykinesia - lack of movement or slow initiation of movement

Postural instability - poor balance, which may lead to frequent falls

Certain drugs can cause Parkinsonism due to their antagonism of dopamine receptors. Which are they?

Phenothiazine (prochlorperazine, others)

First generation antipsychotics (including haloperidol)

Second generation antipsychotics

Dopamine blocking agents

metoclopramide (Reglan) - most likely to produce Parkinsonism when it is overdosed, which is not uncommon in the elderly since it must be reduced for renal dysfunction.