National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Bilateral perisylvian polymicrogyria

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What is bilateral frontoparietal polymicrogyria? What are its symptoms? How is it different from bilateral perisylvian polymicrogyria in how it presents and what symptoms we see?

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What is bilateral frontoparietal polymicrogyria?

Bilateral frontoparietal polymicrogyria (BFPP) is a rare neurological disorder that affects the cerebral cortex (the outer surface of the brain). BFPP specifically affects the frontal and parietal lobes on both sides of the brain (bilateral). Signs and symptoms typically include moderate to severe intellectual disability, developmental delay, seizures, cerebellar ataxia, strabismus, and dysconjugate gaze (eyes that are not aligned). Some cases are caused by mutations in the GPR56 gene and are inherited in an autosomal recessive manner. Treatment is based on the signs and symptoms present in each person.[1][2]
Last updated: 6/8/2015

What are the signs and symptoms of bilateral frontoparietal polymicrogyria?

The signs and symptoms of bilateral frontoparietal polymicrogyria vary but may include:[2][1]
  • Moderate to severe intellectual disability
  • Developmental delay
  • Seizures
  • Dysconjugate gaze (eyes that are not aligned)
  • Ataxia
  • Strabismus
  • Increased muscle tone
  • Finger dysmetria (difficulty controlling speed, distance and/or power of movements)
Last updated: 6/7/2015

What are the signs and symptoms of bilateral perisylvian polymicrogyria?

Signs and symptoms of bilateral perisylvian polymicrogyria (BPP) usually are apparent at birth or become apparent during infancy or childhood. The signs and symptoms, and severity, vary from person to person but may include:[3][4][5][6][7]
  • Partial paralysis of muscles on both sides of the face, tongue, jaw, and throat 
  • Sudden, involuntary spasms of facial muscles
  • Excessive drooling
  • Difficulty with sucking, chewing, and/or swallowing (dysphagia)
  • Difficulty with speech (dysarthria)
  • Seizures
  • Mild spasticity of the limbs (spastic tetraplegia)
  • Developmental delay or learning impairments
  • Mild to severe intellectual disability
  • Contractures present from birth (congenital)
Various other health problems or birth defects may occur in people with BPP, depending on whether an underlying genetic disorder with additional associated symptoms is present.[3][4]
Last updated: 11/26/2018

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  1. Chang B, Walsh CA, Apse K & Bodell A. Polymicrogyria Overview. Gene Reviews. August 6, 2007; http://www.ncbi.nlm.nih.gov/books/NBK1329/. Accessed 3/9/2015.
  2. POLYMICROGYRIA, BILATERAL FRONTOPARIETAL; BFPP. OMIM. April 2014; http://omim.org/entry/606854.
  3. Congenital Bilateral Perisylvian Syndrome. NORD. 2015; http://rarediseases.org/rare-diseases/congenital-bilateral-perisylvian-syndrome/.
  4. Kilinc O, Ekinci G, Demirkol E & Agan K. Bilateral agenesis of arcuate fasciculus demonstrated by fiber tractography in congenital bilateral perisylvian syndrome. Brain Dev. March 2015; 37(3):352-355. https://www.ncbi.nlm.nih.gov/pubmed/24852949.
  5. Stutterd CA, Leventer RJ. Polymicrogyria: a common and heterogeneous malformation of cortical development. Am J Med Genet C Semin Med Genet. June, 2014; 166C(2):227-239. https://onlinelibrary.wiley.com/doi/full/10.1002/ajmg.c.31399.
  6. Stutterd CA, Dobyns WB, Jansen A, Mirzaa G, Leventer RJ. Polymicrogyria Overview. GeneReviews. August 16, 2018; https://www.ncbi.nlm.nih.gov/books/NBK1329/.
  7. Clark M, Neville BG. Familial and genetic associations in Worster-Drought syndrome and perisylvian disorders. Am J Med Genet A. January 1, 2008; 146A(1):35-42. https://www.ncbi.nlm.nih.gov/pubmed/17994559.