Heterotopia

• Focal collections of normal neurons in abnormal locations due to neuronal migration interruption

• Radial neuronal migration fails completely--> Collections of normal “cortical” neurons that fail to reach the cortex --> forming islands of Gray matter in white matter

• FLNA mutation (Chr Xq28), which encodes an actin-binding protein called filamin
• Fatal in males, heterogeneous in females

• Almost always has seizures in 20-30s

• Non enhancing

Subependymal (periventricular) heterotopia

• Most common

• Can be
• Unilateral periventricular nodular heterotopia
• Bilateral periventricular nodular heterotopia
• X-linked dominant disorder
• only seen in females
• lethal in males

• Presentation
• Normal motor function
• Normal development
• Onset of seizures in the second decade of life

Focal subcortical heterotopia

• Presentation
• Depends on size
• Normal to severely abnormal developmental delay
• Normal to severe motor disturbances
• Seizure disorder.

Band heterotopia

• Aka diffuse gray matter heterotopia

• Presentation
• moderate to severe developmental delay
• medically intractable seizures.

• Strongly associated with Classic T1 Lissencephaly

 

 

Marginal glioneuronal heterotopia

• Overmigration of neurons and glial cells into the leptomeninges Microscopically and not visible on imaging.

Feature	Marginal glioneuronal heterotopia	Type 2 cobblestone lissencephaly
Location	Affects a focal part of the brain	Affects the entire cerebral cortex
Appearance	Nodules of neurons and glial cells	Cobblestone" appearance
Severity	Can range from mild to severe	Typically associated with severe symptoms
Symptoms	Developmental delays Seizures Intellectual disability Asymptomatic	Severe developmental delays, Intellectual disability Seizures Movement disorders