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| Parkinson's Disease |
| Etiology •Unknown |
| Pathogenesis •A disease of the nigrostriatal dopaminergic system, with destruction of the melanin bearing neurons of the substantia nigra in the midbrain and the locus ceruleus in the pons. •There is a consequent decrease in dopamine levels in the caudate nucleus and putamen. •Parkinson's Disease is also called "Idiopathic Parkinson's Disease" to distinguish it from other entities which also damage the nigrostriatal system, causing a similar clinical syndrome. •Postencephalitic Parkinsonism was due to destruction of the substantia nigra in cases of Von Economo's encephalitis following World War I. •Drug users of meperidine derivatives have been similarly affected by a contaminant, MPTP., |
| Epidemiology •A common disease of middle and old age, with onset from age 50 to 70 years. •More common in males, especially when onset is before age 50. |
| General Gross Description •The classical gross finding is a marked decrease or loss of the black pigmentation of the substantia nigra. •Otherwise, the brain as a whole appears unremarkable. |
| General Microscopic Description •There are a decreased number of melanin bearing neurons in the substantia nigra and locus ceruleus, with extravasated pigment from dead neurons, and gliosis. •An eosinophilic discrete round intracytoplasmic inclusion called the "Lewy body" is characteristically found in viable appearing neurons. •The Lewy body by EM is made of fine filaments. It contains neurofilament and ubiquetin antigens. Immunohistochemical markers for ubiquitin enable the easy identification of Lewy bodies in microscopic sections. •Lewy bodies are not found in cases of postencephalitic Parkinsonism, or in MPTP intoxication. |
| Clinical Correlation •The syndrome is characterized by involuntary tremors ("pill rolling" tremor of the hands), a forward bending of the trunk standing, a tendency to "pass from a walking to a running pace", and muscular weakness. •The intellect is intact, but dementia from other causes may occur. •Immobility leading to decubitus ulcers and pneumonia is a serious problem in the later stages. •There are effective temporary drug therapies, such as levodopa and deprenyl, but this is a progressive and, eventually, fatal disease after 10 years or longer. •There is a hope that transplants of fetal tissues containing substantia nigra may prove more effective. |
| References • Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1332-1333. • Harrison's Principles of Internal Medicine, 13th Ed: Isselbach et. al. (eds). New York, McGraw-Hill, 1994, pp. 2275-2278. |
| Parkinson's Disease |
| Synopsis by: J. Hasson, MD (TX2000D84500)[610] |
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