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Adult brain tumors: Pathology review
Central nervous system infections: Pathology review
Cerebral vascular disease: Pathology review
Congenital neurological disorders: Pathology review
Dementia: Pathology review
Demyelinating disorders: Pathology review
Headaches: Pathology review
Movement disorders: Pathology review
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Pediatric brain tumors: Pathology review
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Faces of Parkinson's
Parkinson's Disease Assessment
Parkinson's Disease Interventions
Creutzfeldt-Jakob Disease, Parkinson's Disease & Huntington's Disease
Parkinson disease p. 565
Parkinson-like syndrome p. 250
Parkinson disease p. 539
Parkinson disease p. 727
Parkinson disease drugs p. 566
basal ganglia lesions p. 526
benztropine for p. 240
dopaminergic pathways p. 510
drug therapy for p. 565
Lewy bodies p. 536
neurotransmitters for p. 508
nigrostriatal pathway and p. 510
presentation p. 727
proteasome and p. 46
resting tremor in p. 535
seborrheic dermatitis association p. 484
trihexyphenidyl p. 240
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.
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.
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