Pathophysiology
Clinical meaning
Parkinson disease results from progressive loss of dopaminergic neurons in substantia nigra pars compacta with alpha-synuclein Lewy body accumulation. Loss of >60-80% of neurons produces motor features. Levodopa crosses BBB via large neutral amino acid transporter, converted to dopamine. Carbidopa blocks peripheral conversion. Motor complications develop in 40-50% after 5 years.
