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| Microcephaly |
| Etiology •Almost 50% of microencephalic patients have an autosomal recessive form of the disease. •Intrauterine ischemia or infection may also cause this malformation. |
| Pathogenesis •Often due to formation of too few neuroblasts in the germinal plate. •There may be enhanced programed cell death after neuroblasts have reached the cortex. •Ischemia or infection may interfere with formation, migration or survival of cortical neurons., |
| Epidemiology • Microencephaly is uncommon even in patients with chromosome abnormalities. |
| General Gross Description •Microcephaly means small head due to many causes. •Microencephaly means small brain usually under 1000 gm adult weight. •Microencephaly brains usually have a simplified gyral pattern and may have cerebral cortical dysarrangements and white matter heterotopias. •Often basal ganglia, thalamus, and cerebellum are normal in size. |
| General Microscopic Description •Microscopically, microencephalic brains may have vertically arranged cerebral cortical neurons or poor horizontal lamination. •White matter heterotopias consist of an abnormal group of neurons in several areas or just sub- ventricularly. |
| Clinical Correlation •Most microencephalic patients are mentally retarded. |
| References • Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp.1302. • Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp. p 197. |
| Microcephaly |
| Synopsis by: M.L. Grunnet M.D. (TX2000M21300)[61] |
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