Neuronal Migration Disorders
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What is Neuronal Migration Disorders?Is there any treatment?What is the prognosis?What research is being done?OrganizationsWhat is Neuronal Migration Disorders?
Neuronal migration disorders (NMDs) are a group of birth defects caused by the abnormal migration of neurons in the developing
brain and nervous system. In the developing brain, neurons 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. The structural abnormalities found in NMDs include schizencephaly, porencephaly, lissencephaly,
agyria, macrogyria, pachygyria, microgyria, micropolygyria, neuronal heterotopias (including band heterotopia), agenesis of
the corpus callosum, and agenesis of the cranial nerves. 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. 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. 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.
Is there any treatment?
Treatment is symptomatic, and may include anti-seizure medication and special or supplemental education consisting of physical,
occupational, and speech therapies.
What is the prognosis?
The prognosis for children with NMDs varies depending on the specific disorder and the degree of brain abnormality and subsequent
neurological losses.
What research is being done?
The NINDS conducts and supports a wide range of studies that explore the complex systems of normal brain development. The
knowledge gained from these studies provides the foundation for understanding abnormal development and offers hope for new
ways to treat and prevent NMDs.
Select this link
to view a list of studies currently seeking patients.
Organizations
Prepared by:
Office of Communications and Public Liaison
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
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or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice
on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined
that patient or is familiar with that patient's medical history.
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Last updated February 14, 2007
