Substantia nigra is affected in –
Correct Answer: Parkinson's disease
Description: Ans. is 'a' i.e., Parkinson's disease Diseases of Basal gangliao Three distinct biochemical pathways in the basal ganglia normally operate in a balanced fashion: -1 ) Nigrostriatal dopaminergic system; 2) Intrastriatal cholinergic system; 3) GABAergic system which projects from the stratum to globus pallidus and substantia nigra.o When one or more of these pathways become dysfunctional, characteristic motor abnormalities occur. There may be two types of disorder : -Hyperkinetic: - There is excessive and abnormal movement, e.g., Chorea, athetosis and ballism.Hypokinetic: - There is paucity of movement, e.g., Akinesia and Bradykinesia.o The classical example of Basal ganglia disease is Parkinsonism in which there is degeneration of dopaminergic neurons in the substantia nigra pars compacta. The fibers to putamen are most severely affected. A patient with parkinsonism have both hypokinetic and hyperkinetic features : -Hypokinetic : - Bradykinesia, AkinesiaHyperkinetic : - Cogwheel rigidity, Resting tremorDiseasePart of Basal ganglia involvedo ParkinsonismSubstantia nigra pars compacta - Nigrastriatal pathwayo Huntington choreaStriatum (mainly caudate nucleus; may be putamen)o BallismSubthalamic nucleio AthetosisGlobus pallidus (mainly) and Subthalamic nucleus.Pathologic Examination in Parkinsons shows:o Gross / Macroscopically :Pallor of the substantia nigra and locus ceruleuso Microscopic Examination :Loss of catecholaminergic neurons in these regions +# gliosisLewy bodies.o Lewy Bodies : are inclusion bodies found within neurons in Parkinsons disease.Lewy bodies are single or multiple, intra-cytoplasmic, eosinophilic, round and elongated inclusions that often have a dense core surrounded by a pale halo.Ultrastructurally These are composed of fine filaments, densely packed in the core but loose at the rim.
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