Polymicrogyria
| Polymicrogyria | |
|---|---|
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| This child presented with seizures. The coronal true inversion recovery sequence shows thickened and disordered cortex in superior frontal and cingulate gyri bilaterally (arrow). There are small convolutions visible at the corticomedullary junction. The appearance is that of cortical dysplasia, with polymicrogyria more likely than pachygyria due to the small convolutions visible. There are also small foci of grey matter signal in the corpus callosum, deep to the dysplastic cortex (double arrows). These probably represent areas of grey matter heterotopia. | |
| Classification and external resources | |
| ICD-9-CM | 742.2 |
| DiseasesDB | 33975 |
| MeSH | D054220 |
| GeneReviews | |
Polymicrogyria (PMG) is a condition that affects the development of the human brain by multiple small gyri (microgyri) creating excessive folding of the brain leading to an abnormally thick cortex. This abnormality can affect either one region of the brain or multiple regions.
The time of onset has yet to be identified; however, it has been found to occur before birth in either the earlier or later stages of brain development. Early stages include impaired proliferation and migration of neuroblasts, while later stages show disordered post-migration development.
The symptoms experienced differ depending on what part of the brain is affected. There is no specific treatment to get rid of this condition, but there are medications that can control the symptoms such as seizures, delayed development or weakened muscles as some of the noted effects.
Significant technological advances have been made within the past few decades that have allowed more extensive studies to be made regarding syndromes from conditions such as polymicrogyria. Research, imaging, and analysis has shown that distribution of polymicrogryia does not always appear to be random, which revealed different types polymicrogyria. A summary of clinical manifestations of each syndrome can be found below, in the section labelled "Clinical presentation".
BFP appears to be a symmetrical polymicrogyria that extends anteriorly from the frontal poles to the posterior precentral gyrus, and inferiorly to the frontal operculum. Patients who had polymicrogyria distribution similar to this also experienced similar symptoms including delayed motor and language developments, spastic hemiparesis or quadriparesis, and forms of mild mental retardation.
BFPP was one of the first discovered forms of polymicrogyria to have a gene identified linking to the syndromes caused. This gene is called GPR56. Symmetrical distribution is also evident in this form, but more distinctly, patients with BFPP were found to have atrophy of the cerebellum and brain stem, as well as bilateral white matter abnormalities. BFPP is characterized by estopia, global development delay, pyramidal signs, cerebral signs, and seizures. Estopia is also known as dysconjugate gaze, and is a common feature of severe static encephalopathy. This differentiates BFPP from the other bilatieral polymicrogyria syndromes.
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