The three cardinal signs of Parkinson disease are resting tremor, rigidity, and bradykinesia. Postural instability (balance impairment) is sometimes included as the fourth cardinal feature, but balance impairment in Parkinson disease is a late phenomenon. In fact, prominent balance impairment in the first few years suggests that Parkinson disease is not the correct diagnosis.

For more on the initial presentation of Parkinson disease, read here.

The American Academy of Neurology notes that the following clinical features may help predict the rate of progression of Parkinson disease:

• Older age at onset and initial rigidity/hypokinesia can be used to predict (1) a more rapid rate of motor progression in those with newly diagnosed Parkinson disease and (2) earlier development of cognitive decline and dementia; however, initially presenting with tremor may predict a more benign disease course and longer therapeutic benefit from levodopa.

• A faster rate of motor progression may also be predicted if the patient is male, has associated comorbidities, and has PIGD.

• Older age at onset, dementia, and decreased responsiveness to dopaminergic therapy may predict earlier nursing home placement and decreased survival.

For more on the prognosis of Parkinson disease, read here.

Although tremor is the most common initial symptom in Parkinson disease, occurring in approximately 70% of patients, it does not have to be present to make the diagnosis. Tremor is most often described by patients as shakiness or nervousness. It usually begins in one upper extremity and initially may be intermittent.

For more on the clinical presentation of Parkinson disease, read here.

Parkinson disease is a clinical diagnosis. No laboratory biomarkers exist for the condition, and findings on routine MRI and CT scan are unremarkable. No laboratory or imaging study is required in patients with a typical presentation. Such patients are aged 55 years or older and have a slowly progressive and asymmetric parkinsonism with resting tremor and bradykinesia or rigidity. Patients who do not have tremor should generally be considered for MRI evaluation to exclude brain lesions such as stroke, tumor, or demyelination.

For more about the workup of Parkinson disease, read here.

Deep brain stimulation has become the surgical procedure of choice for Parkinson disease for the following reasons:

• It does not involve destruction of brain tissue

• It is reversible

• It can be adjusted as the disease progresses or adverse events occur

• Bilateral procedures can be performed without a significant increase in adverse events

Deep brain stimulation, a form of stereotactic surgery, has made a resurgence in the treatment of Parkinson disease largely because long-term complications of levodopa therapy result in significant disability over time. A better understanding of basal ganglia physiology and circuitry, as well as improvements in surgical techniques, neuroimaging, and electrophysiologic recording, have allowed surgical procedures to be performed more accurately and with lower morbidity.

For more on the treatment of Parkinson disease, read here.

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Cite this article: Robert A. Hauser. Quiz: Do You Know the Basics of Parkinson Disease? Medscape. May 05, 2015.