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Polymicrogyria refers to the abnormal development of the ridges and folds of the brain (gyri) during gestation. It is characterized by an excessive number (poly-) and small size (micro-) of the gyri in the cerebral cortex. Signs and symptoms of polymicrogyria depend on the extent of brain tissue affected, the regions of the brain affected, and whether it is unilateral or bilateral.


The signs and symptoms of polymicrogyria are variable; they depend on the degree and location of polymicrogyria. Infants with bilateral polymicrogyria have more severe symptoms compared to those that have unilateral involvement. Patients with generalized bilateral polymicrogyria present with various neurologic findings such as cognitive impairment, motor delay, refractory seizures, and/or quadriparesis [1] [2] [3] [4]. Polymicrogyria has been associated with malformations such as schizencephaly, cerebellar hypoplasia [5], subcortical heterotopia [6], and periventricular nodular heterotopia [7].

While the symptoms of polymicrogyria vary, there are common clinical presentations based on the region of the brain affected. For example, patients with bilateral polymicrogyria of the frontal cortex often present with cognitive impairment, motor delay, epilepsy, and/or quadriparesis. Bilateral polymicrogyria of frontoparietal cortex results in significant cognitive impairment and motor delay, seizures, cerebellar problems, and/or dysconjugate gaze. Patients with bilateral perisylvian polymicrogyria present with cognitive impairment, epilepsy, pseudobulbar signs, arthrogryposis, and/or lower motor neuron disease. Bilateral polymicrogyria of the parasagittal parieto-occiptal region is associated with mental retardation and/or partial seizures.

  • Multiple congenital contractures, also known as fetal akinesia deformation sequence (FADS) and related terms, result from decreased fetal movement.[ncbi.nlm.nih.gov]


Work up for polymicrogyria consists of a physical exam, a thorough medical history (including maternal pregnancy history and family history), and imaging tests. Congenital infections have been associated with polymicrogyria; the toxoplasmosis, rubella, cytomegalovirus, herpes simplex, and a TORCH screen may be performed for detection of human immunodeficiency virus (HIV) if clinically indicated.

Genetic testing for mutations can be performed. For example, BICD2 has been associated with perisylvian polymicrogyria [8]. Screening for syndromes commonly associated with polymicrogyria, can be useful for determining etiology. Polymicrogyria is often an isolated condition, however, it can occur as a part of genetic syndromes such as 22q11.2 deletion syndrome, Aicardi syndrome, Adams-Oliver syndrome, Chudley-McCullough syndrome, Zellweger spectrum disorder, Galloway-Mowat syndrome, and Joubert syndrome [9].

Magnetic resonance imaging (MRI) is used to diagnose polymicrogyria [10]. MRI images will show abnormalities of the surface of the cortex and the gray-white matter junction [11]. In patients with polymicrogyria, the cortical surface will show a thickened appearance due to the fused and infolded gyri. Other imaging modalities such as computed tomography (CT) do not have sufficient resolution or contrast to show the small gyri characteristic of polymicrogyria.

Brain tissue can be examined at the time of autopsy or during neurosurgery. Gross examination of the cerebral cortex shows an abnormal brain surface consisting of complex convolutions with miniature, fused, superimposed folds and the pia meningeal layer extending across multiple folds [12]. Microscopic examination reveals an unusually thin cerebral cortex with abnormal lamination.

  • Hanchard, Whole-Exome Sequencing Reveals GPIHBP1 Mutations in Infantile Colitis With Severe Hypertriglyceridemia, Journal of Pediatric Gastroenterology and Nutrition, 59, 1, (17), (2014). M.H. Willemsen and T.[doi.org]
  • Hanchard, Whole-Exome Sequencing Reveals GPIHBP1 Mutations in Infantile Colitis With Severe Hypertriglyceridemia, Journal of Pediatric Gastroenterology and Nutrition, 59, 1, (17), (2014). M.H. Willemsen and T.[doi.org]
White Matter Lesions
  • It can occur as an isolated lesion, in association with other brain malformations such as heterotopia or white matter lesions, or as part of several multiple congenital anomaly/mental retardation syndromes.[doi.org]


  • OBJECTIVE: The role of resective surgery in the treatment of polymicrogyria (PMG)-related focal epilepsy is uncertain.[ncbi.nlm.nih.gov]
  • What is the treatment? There is no cure for Microcephaly.[chiarasjourney.com]
  • Treatment and prognosis No specific treatment of polymicrogyria per se is available. Treatment is symptomatic and particularly aimed at controlling epilepsy, a common sequela. Related Radiopaedia articles Promoted articles (advertising)[radiopaedia.org]


  • CONCLUSIONS: Late presenting epilepsy may be a predictor of aunilateral polymicrogyria and is associated with relatively good prognosis. CMV infection and the presence of asphyxia are predictors of worse prognosis.[ncbi.nlm.nih.gov]
  • Therefore, the prognosis will depend on which area is affected, the location and of course the signs and symptoms it causes.[lifepersona.com]
  • Treatment and prognosis No specific treatment of polymicrogyria per se is available. Treatment is symptomatic and particularly aimed at controlling epilepsy, a common sequela. Related Radiopaedia articles Promoted articles (advertising)[radiopaedia.org]


  • It is a highly heterogeneous malformation with variable clinical and imaging features, pathological findings, and etiologies.[ncbi.nlm.nih.gov]
  • It may be associated with a genetic etiology, or may be due to exogenic causes such as infection, or impaired hemodynamic disturbances.[dnatesting.uchicago.edu]


  • Epidemiology Currently the prevalence is unknown. Researchers believe that, although polymicrogyria in all its forms is a fairly common brain malformation, each individual disorder is rare in the population.[lifepersona.com]
  • View Article PubMed Google Scholar Kenneson A, Cannon MJ: Review and meta-analysis of the epidemiology of congenital cytomegalovirus (CMV) infection. Rev Med Virol 2007, 17: 253–276.[doi.org]
Sex distribution
Age distribution


  • The pathophysiological bases are heterogeneous and include extrinsic factors and genetic causes.[ncbi.nlm.nih.gov]
  • It appears that intrauterine infection by cigomegalovirus (CMV) could be the basis of a significant percentage of them; In addition, in the last years, a great number of genes that could be involved in the pathophysiology of this type of cerebral malformations[lifepersona.com]
  • View Article PubMed PubMed Central Google Scholar Comi AM: Pathophysiology of Sturge-Weber syndrome. J Child Neurol 2003, 18: 509–516.[doi.org]


  • This situation suggests a need for more education regarding CMV modes of transmission and prevention on early prenatal visits.[ashg.org]
  • The ankle-foot orthotic can also be used to prevent further deformity of the joint.[medigoo.com]
  • Prevention Prevention is paramount and for this it is appropriate that parents be educated about common seizure presentations.[lifepersona.com]
  • Treatment with anticonvulsant drugs may help prevent, reduce, or control various types of epilepsy associated with CBPS.[rarediseases.org]
  • In the state of Texas, the blood spot is saved for one year after birth, so the two women appealed for the sample to be sent to the Centers for Disease Control and Prevention (CDC) for testing.[foxnews.com]



  1. Barkovich AJ, Linden CL. Congenital cytomegalovirus infection of the brain: imaging analysis and embryologic considerations. AJNR Am J Neuroradiol. 1994;15:703–715.
  2. Dobyns WB, Mirzaa G, Christian SL, et al. Consistent chromosome abnormalities identify novel polymicrogyria loci in 1p36.3, 2p16.1–p23.1, 4q21.21–q22.1, 6q26–q27, and 21q2. Am J Med Genet Part A. 2008;146A:1637–1654.
  3. Guerrini R, Dravet C, Raybaud C, et al. Epilepsy and focal gyral anomalies detected by MRI: electroclinico-morphological correlations and follow-up. Dev Med Child Neurol. 1992;34:706–18.
  4. Barkovich AJ, Kjos BO. Non-lissencephalic cortical dysplasia: correlation of imaging findings with clinical deficits. AJNR Am J Neuroradiol. 1992;13:95–103.
  5. Barkovich AJ, Millen KJ, Dobyns WB. A developmental classification of malformations of the brainstem. Ann Neurol. 2007;62:625–639.
  6. Barkovich AJ. Morphology of subcortical heterotopia: a magnetic resonance study. AJNR Am J Neuroradiol. 2000;21:290–295.
  7. Wieck G, Leventer RJ, Squier WM, et al. Periventricular nodular heterotopia with overlying polymicrogyria. Brain. 2005;128:2811–21.
  8. Ravenscroft G, Di Donato N, Hahn G, et al. Recurrent de novo BICD2 mutation associated with arthrogryposis multiplex congenita and bilateral perisylvian polymicrogyria. Neuromuscul Disord. 2016;26:744-8.
  9. Chapman T, Perez FA, Ishak GE, Doherty D. Prenatal diagnosis of Chudley-McCullough syndrome. Am J Med Genet A. 2016;170:2426-30.
  10. Barkovich AJ. Neuroimaging manifestations and classification of congenital muscular dystrophies. Am J Neuroradiol. 1998;19:1389–96.
  11. Raybaud C, Girard N, Canto-Moreira N, Poncet M. High-definition magnetic resonance imaging identification of cortical dysplasias: micropolygyria versus lissencephaly. In: Guerrini R, Andermann F, Canapicchi R, Roger J, Zifkin BG, Pfanner P, eds. Dysplasias of Cerebral Cortex and Epilepsy. Philadelphia, PA: Lippincott-Raven; 1996:131-44.
  12. Harding B, Copp AJ. Malformations. In: Graham DI, Lantos PL, eds. Greenfield's Neuropathology. 6 ed. London, UK: Arnold; 1997.

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Last updated: 2019-07-11 22:00