Bilateral frontal polymicrogyria

Definition

Bilateral frontal polymicrogyria is one of the rarest subtypes of polymicrogyria. It is a symmetric and bilateral form (in both brain hemispheres) that only involves the frontal lobes without including the area located behind the Sylvius fissure or the area located behind the Rolando sulcus.

Types

Some researchers classify the condition into two different forms: bilateral frontal polymicrogyria and the bilateral frontoparietal.

Cause

The frontoparietal form is caused by changes (mutations) in the GPR56 gene but the cause for the frontal form of polymicrogyira is still not known.

Signs and symptoms

Signs and symptoms included delayed motor and language milestones; spastic (stiffness) hemiparesis (weakness in one side of the body) or quadriparesis (weakness in all four limbs of the body); and mild to moderate intellectual disability. Seizures may also be present.

Clinical presentation

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed.

80%-99% of people have these symptoms

• Delayed speech and language development(Deficiency of speech development)
• Global developmental delay

30%-79% of people have these symptoms

• Intellectual disability, mild(Mental retardation, borderline-mild)
• Spastic tetraparesis

5%-29% of people have these symptoms

• EEG abnormality

Diagnosis

• The diagnosis of PMG is typically made by MRI since computed tomography (CT) and other imaging methods do not have high enough resolution or adequate contrast to identify the small folds that define PMG.<ref>Stutterd CA, Dobyns WB, Jansen A, et al. Polymicrogyria Overview. 2005 Apr 18 [Updated 2018 Aug 16]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2021. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1329/</ref>[1].
• In 5% of cases, PMG is detected on prenatal ultrasound examination by the presence of abnormalities – usually microcephaly and/or associated brain malformations.

Treatment

Treatment is based on the signs and symptoms present in each person.

References

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NIH genetic and rare disease info

• NIH info on Bilateral frontal polymicrogyria

Bilateral frontal polymicrogyria is a rare disease.

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