1. Parkinson's disease Parkinson's disease (PD) is the second-most common
neurodegenerative disorder, after Alzheimer's disease. While classically
considered a movement disorder, there is a growing recognition that
PD produces a wide variety of nonmotor symptoms as well. Early
diagnosis of PD is important for treatment planning and maintaining
the highest quality of life for the longest period of time, yet at its
earliest stages, PD may often be difficult to distinguish from other
causes of parkinsonism.

2. No definitive neuroprotective treatment is yet available, but
symptomatic treatments may provide significant benefit for many
years for the patient with PD. The wide range of treatment options
and strategies, combined with the differing needs and comorbidities
of different patients, means the physician must have detailed
knowledge of multiple drugs from different classes, and how each
is likely to impact the individual PD patient.

3. In addition, nonpharmacologic treatments, from physical and
recreational therapy to surgery, are also central to the optimal
management of PD.
Neurodegeneration in PD is scattered in a multifocal distribution
throughout the brain. This is a progressive process, presumably
starting years or even decades before symptoms emerge and
continuing over many years throughout the course of the disease.

4. The motor features of the disease primarily result from loss of
dopaminergic neurons of the substantia nigra that project to the
caudate nucleus and putamen. Some motor and other nonmotor
features of the disease are likely due to loss of dopaminergic and
nondopaminergic innervation in other brain regions.

5. Cardinal Motor Features
The cardinal motor features of PD are rest tremor, bradykinesia,
rigidity, and postural instability. Onset is usually unilateral. Two of
the first 3 features are required for diagnosis. Postural instability
-- characterized by shuffling, freezing, impaired balance, and falling –
usually occurs later in the disease course.

6. Early Cardinal Motor Signs (2 of 3 required for diagnosis)
Rest tremor
Bradykinesia
Rigidity
Tremor: Occurs with hands at rest, and is often described as
"pill rolling." Leg tremor is also common; tremor may also affect
lips, neck, tongue, or face, though these often occur later in PD.
Tremor classically abates with action but some patients also display
a significant postural or action tremor, which may be more intrusive
in activities of daily living. In 75% of patients, unilateral rest tremor
is the first visible motor sign of PD.

7. Bradykinesia: Slowness of movement is insidious and may be
initially mistaken for normal aging, the effects of arthritis, or even
depression. Bradykinesia is often the most disabling motor feature
of the disease, slowing mobility and impairing activities of daily living.

8. Rigidity: Cogwheel rigidity may be assessed during passive motion
of the limbs or neck, and may be worsened with activity of the
contralateral limb. Stiffness is not always reported by the patient,
although they may complain of common joint-related pain
syndromes such as tennis elbow or low back pain.