Schizencephaly is an extremely rare developmental birth defect characterized by abnormal slits, or clefts, in the cerebral hemispheres of the brain. Babies with clefts in both hemispheres (bilateral clefts) commonly have:

• Developmental delays
• Delays in speech and language skills
• Problems with brain-spinal cord communication

Individuals with clefts in only one hemisphere (unilateral clefts) are often paralyzed on one side of the body but may have average to near-average intelligence. Individuals with schizencephaly also may have:

• An abnormally small head
• Cognitive delay and impairment
• Partial or complete paralysis
• Poor muscle tone

Most will experience seizures. Some individuals may have an excessive accumulation of fluid in the brain called hydrocephalus.

Signs and symptoms of schizencephaly may include:

• Developmental delay
• Seizures
• Abnormally small head (microcephaly)
• Intellectual disability
• Partial or complete paralysis
• Poor muscle tone (hypotonia)
• Hydrocephalus

Severity of symptoms depends on many factors, including the extent of the clefting and whether or not other brain abnormalities are present. For example, people with a small cleft in one hemisphere may have paralysis on one side of the body and little to no intellectual disability, while clefts in both hemispheres can lead to quadriplegia (paralysis of both arms and legs) and severe intellectual disability.