What is Pachygyria?

Pachygyria (PGY) is a rare developmental disorder resulting from the abnormal migration of neurons in the developing brain and nervous system. Pachygyria is not a specific malformation (like lissencephaly) but rather is used to generally describe physical characteristics of the brain. With pachygyria, the gyri are relatively few are are usually broad and flat. The condition is also known as “incomplete lissencephaly”.  Pachygyria is a milder variant of lissencephaly, and part of the lissencephaly spectrum of disorders. Pachygyria is also seen in metabolic central nervous system (CNS) disorders, such as Zellweger Syndrome (ZS).


In most cases, people with pachygyria have moderate to severe developmental and intellectual delays and epilepsy.  Poor muscle tone (hypotonia), poor muscle control, feeding/swallowing difficulties, and small head size (microcephaly) are also frequently associated with this condition. The onset and severity of seizures are determined by the extent of malformation. Infantile spams are common before the age of 2. Intractable epilepsy is common as well.


Magnetic Resonance Imaging (MRI) is commonly used for diagnosis. It provides a high contrast image for better delineation of white and gray matter. Pachygyria shows on an MRI as thickened cerebral cortices with few and large gyri and incomplete development of Sylvian fissures.


Pachygyria is caused by a breakdown in the fetal neuronal migration process due to genetic or possible environmental factors.


Symptoms can vary greatly from person to person, so treatment is symptomatic. It may include anti-seizure medication, physical therapy, occupational therapy, speech therapy, and/or vision therapy.


The prognosis for children with pachygyria varies depending on the degree of brain abnormality and subsequent neurological signs and symptoms.