Parkinson disease
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External References
First Aid
2022
2021
2020
2019
2018
2017
2016
Akinesia in Parkinson disease p. 719
Antimuscarinic drugs
Parkinson disease p. 568
Antipsychotic drugs p. 597
Parkinson-like syndrome p. 252
Dopamine p. 243, 334
Parkinson disease p. 568
Gait disturbance
Parkinson disease p. 539
Gait disturbances
Parkinson disease p. 719
MAO inhibitors p. 599
Parkinson disease p. 568
Metoclopramide p. 409
Parkinson-like syndrome p. 252
Muscarinic antagonists p. 242, 712
Parkinson disease p. 568
Nausea
Parkinson disease drugs p. 569
Neurons p. 507
Parkinson disease p. 568
Parkinson disease p. 538
basal ganglia lesions p. 528
benztropine for p. 242
dopaminergic pathways p. 514
drug therapy for p. 568
Lewy bodies p. 538
neurotransmitters for p. 512
nigrostriatal pathway and p. 514
presentation p. 719
proteasome and p. 46
resting tremor in p. 537
seborrheic dermatitis association p. 488
trihexyphenidyl p. 242
Parkinson-like syndrome p. 252
Reserpine
Parkinson-like syndrome p. 252
Rigidity in Parkinson disease p. 719
Substantia nigra
Parkinson disease p. 719
Transcript
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Parkinson’s disease, which is sometimes called Parkinson disease, Parkinson’s, or PD, is a movement disorder where the dopamine-producing neurons in the substantia nigra of the brain undergo degeneration.
Parkinson’s is one of the most common neurological disorders. It’s a progressive, adult-onset disease, and it gets more common with age. Most of the time, there’s no known cause. But in a few cases, there might be a genetic cause, like mutations in the PINK1, parkin, or alpha synuclein genes, and in rare cases, Parkinsonian symptoms may be caused by MPTP, a toxic impurity that can be found in the recreational drug MPPP or desmethylprodine, which is a synthetic opioid.
In other people, one or more risk factors, rather than a single outright cause, might contribute to Parkinson’s, for example pesticide exposure or DNA variants in genes like LRRK2.
No matter what the cause is, Parkinson’s derives from the death of dopamine-producing, or dopaminergic, neurons in the substantia nigra. The name substantia nigra means “black substance,” since it is darker than other brain regions when you look at a slice of the brain on an autopsy.
We usually refer to the substantia nigra as if it’s in a single location, but there are actually two of these regions in the brain, one on each side of the midbrain. The substantia nigra is a part of the basal ganglia, a collection of brain regions that control movement through their connections with the motor cortex.
In Parkinson’s, these darkened areas of substantia nigra gradually disappear. Under a microscope, Lewy bodies, which are eosinophilic, round inclusions made of alpha-synuclein protein are present in the affected substantia nigra neurons before they die. The function of alpha-synuclein is unknown, as well as the significance of Lewy bodies, and they are both found in other diseases like Lewy body dementia and multiple system atrophy.
Summary
Parkinson's is a progressive movement disorder caused by degeneration of dopamine-producing neurons in the substantia nigra, specifically in the pars compacta, which leads to resting tremor, rigidity, problems initiating movement, and postural instability, and for which therapy primarily focuses on increasing brain dopamine.
There is no cure for this condition, but medications can increase dopamine levels in the brain and control tremors. There is also deep-brain stimulation, which involves an implantable device that directly sends electrical signals to the basal ganglia that counteract the abnormal signaling in Parkinson's.
Sources
- "Robbins Basic Pathology" Elsevier (2017)
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "Pathophysiology of Disease: An Introduction to Clinical Medicine 7/E (ENHANCED EBOOK)" McGraw Hill Professional (2014)
- "CURRENT Medical Diagnosis and Treatment 2020" McGraw Hill Professional (2019)
- "Parkinson's disease" The Lancet (2015)
- "Parkinson's disease" The Lancet (2004)
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