Parkinson disease (PD) is a degenerative disorder of nervous system classified as movement disorder. Its most characteristic symptoms are rest tremor, bradykinesia, rigidity, impairment balance, coordination and gait. It is caused by death of brain dopamine neurons. Most PD cases are sporadic, but there are also genetic causes and some cases provoked by vascular injuries.
PD diagnosis is performed by neurologists based on medical history and neurological examination; in some doubtful cases, DAT-scan (a type of imaging technique) can be useful to differentiate essential tremor from PD. However, DAT-scan is not useful in the differential diagnosis of PD from parkinsonisms like progressive supranuclear palsy (PNP) or Lewy body dementia.