- Rest tremor of a limb (shaking with the limb at rest)
- Slowness of movement (bradykinesia)
- Rigidity (stiffness, increased resistance to passive movement) of the limbs or trunk
- Poor balance (postural instability)
When at least two of these symptoms are present, and especially if they are more evident on one side than the other, a diagnosis of PD is made, unless there are atypical features that suggest an alternative diagnosis. Patients may first realize something is wrong when they develop a tremor in a limb; movements are slowed and activities take longer to perform; or they experience stiffness and have balance problems. Initially, symptoms are a variable combination of tremor, bradykinesia, rigidity and postural instability. Symptoms typically begin on one side of the body and spread over time to the other side.
Changes occur in facial expression, so that there is a certain facial fixity (blank expression showing little emotion) or a staring appearance (due to reduced frequency of eye blinking). Complaints of a frozen shoulder or foot drag on the affected side are not uncommon. As symptoms come on gradually, older patients may attribute these changes to aging. The tremor is thought to be “shakiness,” bradykinesia is regarded as normal “slowing down,” and stiffness is attributed to arthritis. The stooped posture, common to PD, may be attributed to age or osteoporosis. Both younger and older patients may experience initial symptoms for a year or more before seeking medical evaluation.
Parkinson disease affects 1 in 100 people over the age of 60, with the average age of onset being 60 years. It can also affect younger people. Young-onset Parkinson disease (onset at age 40 or younger) is estimated to occur in 5 – 10% of patients with PD.
