Synonyms
Brain with excessive weight; Large brain; Large occipito-frontal head circumference; Macrocephaly; Macroencephaly; Overgrowth, hemimegalencephaly; P13K-AKT-mTOR pathogenesis; Ras/MAPK pathway
Short Description or Definition
Megalencephaly means that a brain is larger than normal and is usually defined when brain size is greater than two standard deviations above normal (Almgren et al. 2008; Gooskens et al. 1988; Olney 2007; Petersson et al. 1999). The term is a derivative of the Greek words encephalon, referring to the brain, and mega, referring to large.
Categorization
Typically with megalencephaly, there is also a large head size, sometimes referred to as macrocephaly (see Dubois et al. 2014; Lainhart et al. 2006) as there is an intimate relationship between brain growth and head size in infancy (Tate et al. 2007). However, large head size or macrocephaly does not always mean that the brain inside is large or megalencephalic (DeMeyer 1972; Homem et al. 2015; van der Knaap...
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Bigler, E.D., Petrie, J.A. (2018). Megalencephaly. In: Kreutzer, J.S., DeLuca, J., Caplan, B. (eds) Encyclopedia of Clinical Neuropsychology. Springer, Cham. https://doi.org/10.1007/978-3-319-57111-9_1565
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