Late-stage Parkinson disease.

The cardinal symptoms of Parkinson disease (PD) are asymmetrical bradykinesia, rigidity, resting tremor and postural instability. However, the presence and spectrum of, and disability caused by, nonmotor symptoms (NMS) are being increasingly recognized. NMS include dementia, psychosis, depression and apathy, and are a major source of disability in later stages of PD, in association with axial symptoms that are resistant to levodopa therapy. The model of clinical progression of PD should, therefore, incorporate NMS, instead of being restricted to motor signs and levodopa-induced motor complications. Patients with disabling motor complications are classified as having advanced PD, which has been thought to represent the ultimate stage of disease. However, deep brain stimulation to treat motor complications has dramatically changed this scenario, with implications for the definition of advanced-stage disease. As treatment improves and survival times increase, patients are increasingly progressing to a later phase of disease in which they are highly dependent on caregivers, and disability is dominated by motor symptoms and NMS that are resistant to levodopa. In this article, we review the changing landscape of the later stages of PD, and propose a definition of late-stage PD to designate patients who have progressed beyond the advanced stage.