Parkinsonism
Parkinsonism is a clinical syndrome characterized by tremor, bradykinesia (slowed movements), rigidity, and postural instability. These are the four motor symptoms found in Parkinsons disease (PD), after which it is named, dementia with Lewy bodies (DLB), Parkinsons disease dementia (PDD), and many other conditions. This set of symptoms occurs in a wide range of conditions and may have many causes, including neurodegenerative conditions, drugs, toxins, metabolic diseases, and neurological conditions other than PD.

Signs and symptoms
Parkinsonism is a clinical syndrome characterized by the four motor symptoms found in Parkinsons disease: tremor, bradykinesia (slowed movements), rigidity, and postural instability.Parkinsonism gait problems can lead to falls and serious physical injuries. Other common symptoms include:

Tremors when resting (mostly in the hands)
Short, shuffling gait
Slow movements (bradykinesia)
Loss of sound perception leading to low, soft speech
Difficulty sleeping
Dry skin
Apathy
Lack of facial expressions
Balance problems
Frequent falls
Very small handwriting
Rigid, stiff muscles
Cogwheeling (jerky feeling in arm or leg)

Conditions
Parkinsonism occurs in many conditions.

Neurological
Neurodegenerative conditions and Parkinson plus syndrome that can cause parkinsonism include:
Corticobasal degeneration
Dementia with Lewy bodies
The relationship (if any) with essential tremor is not clear.
Frontotemporal dementia (Picks disease)
Gerstmann–Sträussler–Scheinker syndrome
Huntingtons disease
Lytico-bodig disease (ALS complex of Guam)
Multiple system atrophy (Shy–Drager syndrome)
Neuroacanthocytosis
Neuronal ceroid lipofuscinosis
Olivopontocerebellar atrophy
Pantothenate kinase-associated neurodegeneration, also known as neurodegeneration with brain iron accumulation
Parkin mutation (hereditary juvenile dystonia)
Parkinsons disease
Parkinsons disease dementia
Progressive supranuclear palsy
Wilsons disease
X-linked dystonia parkinsonism (Lubag syndrome)

Drug-induced ("pseudoparkinsonism")
About 7% of people with parkinsonism developed symptoms as a result of side effects of medications, mainly neuroleptic antipsychotics especially the phenothiazines (such as perphenazine and chlorpromazine), thioxanthenes (such as flupenthixol and zuclopenthixol) and butyrophenones (such as haloperidol), and rarely, antidepressants. Yet another drug that can induce parkinsonism is the antihistaminic medication cinnarizine, usually prescribed for motion sickness; this is because besides antagonizing histamine receptors this drug antagonizes the dopamine D2 receptors. The incidence of drug-induced parkinsonism increases with age. Drug-induced parkinsonism tends to remain at its presenting level and does not worsen like Parkinsons disease.Implicated medications include:

Antipsychotics
Lithium
Metoclopramide
MDMA addiction and frequent use
Tetrabenazine
Cinnarizine

Infectious
Creutzfeldt–Jakob disease
Encephalitis lethargica
HIV infection and AIDS

Toxins
Evidence exists of a link between exposure to pesticides and herbicides and PD; a two-fold increase in risk was seen with paraquat or maneb/mancozeb exposure.Chronic manganese (Mn) exposure has been shown to produce a parkinsonism-like illness characterized by movement abnormalities. This condition is not responsive to typical therapies used in the treatment of PD, suggesting an alternative pathway than the typical dopaminergic loss within the substantia nigra. Manganese may accumulate in the basal ganglia, leading to the abnormal movements. A mutation of the SLC30A10 gene, a manganese efflux transporter necessary for decreasing intracellular Mn, has been linked with the development of this parkinsonism-like disease. The Lewy bodies typical to PD are not seen in Mn-induced parkinsonism.Agent Orange may be a cause of parkinsonism, although evidence is inconclusive and further research is needed.Other toxins that have been associated with parkinsonism are:

Annonaceae
Carbon monoxide
Carbon disulfide
Cyanide
Ethanol
Hexane
Maneb/Mancozeb
Mercury
Methanol
MPTP
Paraquat
Rotenone
Toluene (inhalant abuse: "huffing")

Vascular
Binswangers disease (subcortical leukoencephalopathy)
Vascular dementia (multi-infarct)

Other
Chronic traumatic encephalopathy (boxers dementia or pugilistic encephalopathy)
Damage to the brain stem (especially dopaminergic nuclei of the substantia nigra),basal ganglia (especially globus pallidus) and the thalamus.
Hypothyroidism
Orthostatic tremor
Paraneoplastic syndrome: neurological symptoms caused by antibodies associated with cancers
Rapid onset dystonia parkinsonism
Autosomal recessive juvenile parkinsonism

Society and culture
In the United States, the 2021 National Defense Authorization Act (NDAA) added parkinsonism to the list of presumptive conditions associated with Agent Orange exposure, enabling affected service members to receive Veterans Affairs disability benefits.

References
External links

GeneReviews/NIH/NCBI/UW entry on Perry syndrome
GeneReviews/NCBI/NIH/UW entry on X-Linked Dystonia-Parkinsonism