WordNet

bring disorder to (同)disarray
a physical condition in which there is a disturbance of normal functioning; "the doctor prescribed some medicine for the disorder"; "everyone gets stomach upsets from time to time" (同)upset
a disturbance of the peace or of public order
the movement of persons from one country or locality to another
(chemistry) the nonrandom movement of an atom or radical from one place to another within a molecule
a group of people migrating together (especially in some given time period)
the periodic passage of groups of animals (especially birds or fishes) from one region to another for feeding or breeding
not arranged in order (同)unordered

PrepTutorEJDIC

〈U〉『無秩序』,混乱,乱雑(confusion) / 《しばしば複数形で》(社会的・政治的な)粉争,騒動 / 〈C〉(肉体的・精神的な)不調,異常,障害 / …‘の'秩序を乱す / 〈心身〉‘に'異常を起こさせる
〈U〉〈C〉移住,(動物の)移動 / 〈C〉《集合的に》(人・動物などの)移動の群
神経単位,神経細胞,ニューロン,ノイロン

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/05/10 20:34:31」(JST)

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Brain MRI, T1 weighted on a transversal plane, of a 8-month old boy with lissencephaly. Note the scarce and wide gyri, mostly on the parietal, temporal and occipital lobes, the absence of a true Sylvian cissure, and the augmented thickness of the gray matter. The boy had a severe developmental delay and seizures.

Neuronal migration disorder (NMD) refers to a heterogenous group of disorders that, it is supposed, share the same etiopathological mechanism: a variable degree of disruption in the migration of neuroblasts during neurogenesis.^[1] The neuronal migration disorders are cerebral dysgenesis, brain malformations caused by primary alterations during neurogenesis; on the other hand, brain malformations are highly diverse and refer to any insult to the brain during its formation and maturation due to intrinsic or extrinsic causes that ultimately will alter the normal brain anatomy. However, there is some controversy in the terminology because virtually any malformation will involve neuroblast migration, either primarily or secondarily.

Overview

NMDs occur in the instance that 1) neuroblasts do not migrate from all of the ventricles or migrate only part of the way, 2) only some of the neuroblasts reach the cortical layer, 3) neuroblasts overshoot the appropriate cortical layer and protrude into the subarachnoid space, or 4) the late stage organization of the neuronal layer in the cortex is disrupted. Abnormal migration ultimately results in abnormal gyral formation. ^[2]

Symptoms

Symptoms vary according to the abnormality, but often feature poor muscle tone and motor function, seizures, developmental delays, mental retardation, failure to grow and thrive, difficulties with feeding, swelling in the extremities, and a smaller than normal head. Most infants with an NMD appear normal, but some disorders have characteristic facial or skull features that can be recognized by a neurologist.^[3]

Cause

In the developing brain, neural stem cells must migrate from the areas where they are born to the areas where they will settle into their proper neural circuits. Neuronal migration, which occurs as early as the second month of gestation, is controlled by a complex assortment of chemical guides and signals. When these signals are absent or incorrect, neurons do not end up where they belong. This can result in structurally abnormal or missing areas of the brain in the cerebral hemispheres, cerebellum, brainstem, or hippocampus.^[3]

Several genetic abnormalities in children with NMDs have been identified. Defects in genes that are involved in neuronal migration have been associated with NMDs, but the role they play in the development of these disorders is not yet well-understood. ^[3]

A study in Sweden investigated the impact of environmental factors on NMDs. The study indicated that there might be an impact of low or subnormal maternal BMI before and during pregnancy, maternal infection, such as rubella, and maternal smoking on fetal brain development, including neuronal migration. The roles of maternal BMI and congenital infections should be tested in future analytical studies.^[4]

Treatment

Treatment is symptomatic, and may include anti-seizure medication and special or supplemental education consisting of physical, occupational, and speech therapies.^[3]

Prognosis

The prognosis for children with NMDs varies depending on the specific disorder and the degree of brain abnormality and subsequent neurological signs and symptoms.^[3]

NMD Syndromes

More than 25 syndromes resulting from abnormal neuronal migration have been described. Among them are syndromes with several different patterns of inheritance; genetic counseling thus differs greatly between syndromes.^[3]

Lissencephaly
Schizencephaly
Porencephaly
Pachygyria
Polymicrogyria
Agyria
Macrogyria
Microgyria
Micropolygyria
Neuronal heterotopias
Agenesis of the corpus callosum
Agenesis of the cranial nerves
Band heterotopias

Focal cortical dysplasia. Miller-Dieker syndrome, muscle-brain-eye syndrome, Fukuyama congenital muscular dystrophy and Walker Warburg syndrome are genetic disorders associated with lissencephaly.^[5]

References

^ Sarnat, Harvey (1992). Cerebral dysgenesis, embryology and clinical expression. New York, US: Oxford University Press. ISBN 0-19-506442-9.
^ Agamanolis, Dimitri (January 2014). "MALFORMATIONS OF CORTICAL DEVELOPMENT AND NEURONAL MIGRATION DEFECTS". Neuropathology-Web.org. NEOMED. Retrieved 3 Feb 2014.
^ ^a ^b ^c ^d ^e ^f "NINDS Neuronal Migration Disorders Information Page". National Institute of Neurological Disorders and Stroke. National Institutes of Health. 30 September 2011. Retrieved 3 Feb 2014.
^ Naumburg, E.; Strömberg, B.; Kieler, H. (2012). "Prenatal Characteristics of Infants with a Neuronal Migration Disorder: A National-Based Study". International Journal of Pediatrics 2012: 1. doi:10.1155/2012/541892. edit
^ Spalice, Alberto; Pasquale, P; Francesco, N (2009). "Neuronal migration disorders: clinical, neuroradiologic and genetic aspects". Acta Paediatrica 98: 421–433. doi:10.1111/j.1651-2227.2008.01160.x. Cite uses deprecated parameters (help)

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5. 自閉症スペクトラム障害：用語、疫学および病因 autism spectrum disorder terminology epidemiology and pathogenesis

English Journal

Cell migration in schizophrenia: Schizophrenia patient-derived cells do not regulate motility in response to extracellular matrix.

Tee JY1, Sutharsan R1, Fan Y1, Mackay-Sim A2.
Molecular and cellular neurosciences.Mol Cell Neurosci.2017 Mar 9. pii: S1044-7431(16)30178-6. doi: 10.1016/j.mcn.2017.03.005. [Epub ahead of print]
PMID 28286248

Role of a circadian-relevant gene NR1D1 in brain development: possible involvement in the pathophysiology of autism spectrum disorders.

Goto M1, Mizuno M2, Matsumoto A1, Yang Z1, Jimbo EF1, Tabata H2, Yamagata T1, Nagata KI2,3.
Scientific reports.Sci Rep.2017 Mar 6;7:43945. doi: 10.1038/srep43945.
PMID 28262759

Central nervous system anomalies in two females with Borjeson-Forssman-Lehmann syndrome.

Kasper BS1, Dörfler A2, Di Donato N3, Kasper EM4, Wieczorek D5, Hoyer J6, Zweier C6.
Epilepsy & behavior : E&B.Epilepsy Behav.2017 Feb 23;69:104-109. doi: 10.1016/j.yebeh.2017.01.022. [Epub ahead of print]
PMID 28237832