Lissencephaly
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Introduction[edit | edit source]
Lissencephaly (LIS) is a spectrum that includes various brain malformations. [1] Its prevalence is estimated at 11.7 to 40 per million births. [2]
It is derived from the combination of two Greek words meaning soft ("lissos") and brain ("enkephalos"). [2] This smooth appearance of the brain, which can be observed in MRI imaging, is associated with malformations of cortical development such as agyria (absence of gyrus), pachygyria (extremely wide gyrus), and subcortical band heterotopia (double cortex). [1][3]
Lissencephaly is generally divided into two subtypes: type 1 (classic LIS) and type 2 (cobblestone LIS). [4]
Type 1 can present in different forms such as isolated LIS, Miller-Dieker Syndrome (MDS), Norman-Roberts syndrome, and X-linked LIS with ambiguous genitalia (XLAG). [5][6]
Type 2 represents the severe end of a spectrum and can present in three syndromes: Walker-Warburg syndrome (WWS), muscle eye-brain (MEB) disease, and Fukuyama congenital muscular dystrophy (FCMD). [7][8][6]
Clinically Relevant Anatomy[edit | edit source]
The cerebral cortex is the outermost part of the brain surrounded by meninges. [9] It contains about 16 billion neurons, making up more than eighty percent of the total weight of the brain. [10]
The development of the cerebral cortex, which is anatomically composed of the neocortex (or isocortex) and allocortex, [11] begins in the uterus at the rostral (anterior) portion of the neural tube. [12] With the proliferation of neurons in the forebrain, the 6-layer structure, which is the initial state of the neocortex, is formed. [13][11]
Later, as the volume of the brain grows, folding occur, forming the gyrus and sulcus of the brain. [14] This process, called gyrification, is an adaptation of the brain to fit into the cranium, [4] starts in the 2nd trimester of gestation, [12] peaks in early adolescence, stabilise in adulthood and regresses with aging. [15]
Gyrification is also important for the functional organization of the brain. [4] Prominent sulci such as Sylvian, central, parieto-occipital and calcarine divide the brain roughly into 4 lobes (frontal, parietal, temporal, occipital) each of which is specialized functions. [9][16]
As in lissencephaly, disruptions that occur in the gyrification process cause changes in the structure and thus function of the brain, leading to intellectual, motor disability and intractable epilepsy. [12][4]
Pathological Process[edit | edit source]
Clinical Presentation[edit | edit source]
Diagnostic Procedures[edit | edit source]
Outcome Measures[edit | edit source]
Management[edit | edit source]
Differential Diagnosis[edit | edit source]
Resources[edit | edit source]
References[edit | edit source]
- ↑ 1.0 1.1 Koenig M, Dobyns WB, Di Donato N. Lissencephaly: Update on diagnostics and clinical management. European Journal of Paediatric Neurology. 2021 Nov 1;35:147-52.
- ↑ 2.0 2.1 Fry AE, Cushion TD, Pilz DT. The genetics of lissencephaly. InAmerican Journal of Medical Genetics Part C: Seminars in Medical Genetics 2014 Jun (Vol. 166, No. 2, pp. 198-210).
- ↑ Malinger G, Kidron D, Schreiber L, Ben‐Sira L, Hoffmann C, Lev D, Lerman‐Sagie T. Prenatal diagnosis of malformations of cortical development by dedicated neurosonography. Ultrasound in Obstetrics and Gynecology: The Official Journal of the International Society of Ultrasound in Obstetrics and Gynecology. 2007 Feb;29(2):178-91.
- ↑ 4.0 4.1 4.2 4.3 Fernández V, Llinares‐Benadero C, Borrell V. Cerebral cortex expansion and folding: what have we learned?. The EMBO journal. 2016 May 17;35(10):1021-44.
- ↑ Herrera JF, Ramírez RG, Zárate MD. Lisencefalia tipo I: síndrome de Miller-Dieker. Informe de un caso. Revista Mexicana de Pediatría. 1999;66(4):157-60.
- ↑ 6.0 6.1 Juric-Sekhar G, Hevner RF. Malformations of cerebral cortex development: molecules and mechanisms. Annual Review of Pathology: Mechanisms of Disease. 2019 Jan 24;14:293-318.
- ↑ Shenoy AM, Markowitz JA, Bonnemann CG, Krishnamoorthy K, Bossler AD, Tseng BS. Muscle-eye-brain disease. Journal of clinical neuromuscular disease. 2010 Mar;11(3):124.
- ↑ Angelini C, Angelini C. Fukuyama congenital muscular dystrophy: walker-warburg syndrome. Springer International Publishing; 2018.
- ↑ 9.0 9.1 Javed K, Reddy V, Lui F. Neuroanatomy, cerebral cortex [Internet]. Treasure Island.
- ↑ Azevedo FA, Carvalho LR, Grinberg LT, Farfel JM, Ferretti RE, Leite RE, Filho WJ, Lent R, Herculano‐Houzel S. Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled‐up primate brain. Journal of Comparative Neurology. 2009 Apr 10;513(5):532-41.
- ↑ 11.0 11.1 Cadwell CR, Bhaduri A, Mostajo-Radji MA, Keefe MG, Nowakowski TJ. Development and arealization of the cerebral cortex. Neuron. 2019 Sep 25;103(6):980-1004.
- ↑ 12.0 12.1 12.2 Quezada S, Castillo‐Melendez M, Walker DW, Tolcos M. Development of the cerebral cortex and the effect of the intrauterine environment. The Journal of physiology. 2018 Dec;596(23):5665-74.
- ↑ Agirman G, Broix L, Nguyen L. Cerebral cortex development: an outside‐in perspective. FEBS letters. 2017 Dec;591(24):3978-92.
- ↑ Welker W. Why does cerebral cortex fissure and fold? A review of determinants of gyri and sulci. Cerebral Cortex: comparative structure and evolution of Cerebral Cortex, Part II. 1990:3-136.
- ↑ Raznahan A, Shaw P, Lalonde F, Stockman M, Wallace GL, Greenstein D, Clasen L, Gogtay N, Giedd JN. How does your cortex grow?. Journal of Neuroscience. 2011 May 11;31(19):7174-7.
- ↑ Stiles J, Jernigan TL. The basics of brain development. Neuropsychology review. 2010 Dec;20(4):327-48.
