Bilateral Perisylvian Polymicrogyria: Causes, Symptoms, and Treatment
Medically reviewed by Achuta Uppu, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Bilateral Perisylvian Polymicrogyria?
A neurologist, a doctor who treats brain and nerve problems, usually leads care. Children often see a pediatric neurologist, a children's brain doctor. A gene doctor and an epilepsy doctor may also help. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is Bilateral perisylvian polymicrogyria?
Bilateral perisylvian polymicrogyria is a rare disease of the brain. It affects the outer layer of the brain, called the cerebral cortex. It harms the area around a groove called the Sylvian fissure, on both sides of the brain. This area normally forms deep folds and grooves. In this disease the grooves form wrong. The result is many small, extra folds. The name polymicrogyria means too many small folds on the surface of the brain.
It is also called congenital bilateral perisylvian syndrome. Symptoms usually start at birth, in infancy, or later in childhood.
Symptoms
Common signs include:
- Weak or partly paralyzed face, tongue, jaw, or throat muscles.
- Trouble speaking and swallowing.
- Heavy drooling.
- Seizures, which many people have.
- Intellectual disability, which means trouble with learning and daily skills. It can be mild or severe.
- Slow speech and language growth, and low muscle tone in infants.
Some children also have trouble with movement, feeding difficulties, or other birth differences.
Causes and who gets it
Changes in genes cause the disease. The causes can include changes in single genes and changes in chromosomes, such as 22q11.2 deletion syndrome. The way it runs in families depends on the cause. In some forms, a child must get two changed gene copies, one from each parent, to have the disease. Most cases happen in one person with no family history. But sometimes more than one family member has it.
For polymicrogyria in general, a virus called cytomegalovirus caught during pregnancy is a known cause. It has also been reported in connection with problems in twin pregnancies.
How doctors diagnose it
Doctors base the diagnosis on the pattern of symptoms and detailed testing of the nervous system, including brain imaging. The key test is an MRI, a scan that uses magnets to show the abnormal brain structure and where it is. In people with seizures, an EEG, a test that records the brain's electrical signals through sensors on the scalp, can show the seizure type. Doctors also use genetic testing, because several genes are linked to this brain change.
Treatment
The brain malformation cannot be reversed, but the symptoms can be treated. For seizures, the first treatment is anti-seizure medicine, and the choice depends on the seizure type. Some seizures are hard or impossible to control with medicine. People who still have seizures after two or more medicines may be sent to a special epilepsy center for other options.
Many people benefit from occupational, physical, and speech therapy. These help with movement, daily skills, and speech.
When to see a doctor
Call 911 if a child has a seizure that lasts a long time, has trouble breathing, or turns blue. Call the doctor for any first seizure, new trouble swallowing that leads to choking, or a child who stops gaining skills. Heavy drooling with feeding trouble also needs a quick check.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either can coordinate care between the many specialists a rare disease involves. They can also help manage long-term needs such as therapy.
Common questions
Is bilateral perisylvian polymicrogyria the same as cerebral palsy?
No. It is a difference in how the brain formed before birth, though it can cause movement problems like those of cerebral palsy. Conditions often seen with polymicrogyria include cerebral palsy, motor delays, and speech delays.
Can it be cured?
No. The brain malformation cannot be reversed. But treatments can ease symptoms, and many people benefit from seizure medicine and therapies.
Will my child have seizures?
About 90 percent of people with polymicrogyria develop seizures at some point, and most of these begin in childhood. People with the bilateral form often have several seizure types. An EEG and a neurologist can help find the seizure type and choose treatment.
Can it run in families?
Most cases happen in one person with no family history. Sometimes more than one family member has it, and the way it runs in families depends on the cause. A geneticist, a doctor who studies genes, can help a family understand the chance of it happening again.
Sources
- NIH Genetic and Rare Diseases Information Center - Congenital bilateral perisylvian syndrome
- Epilepsy Foundation - Polymicrogyria (PMG)
- MedlinePlus Genetics - Polymicrogyria
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
