callosum is a structure in the brain that connects the right and left sides of
your brain. “Agenesis” is a word that means “not formed” or “absence of an
organ.” Corpus callosum agenesis is a birth defect where the connection between
the right and left hemispheres of the brain is not formed or is incompletely
What Is Corpus Callosum Agenesis?
callosum is a curved structure inside the brain that connects the right and
left sides of the brain. In the corpus callosum, 200 million nerve fibers pass
information back and forth between the hemispheres of the brain.
complete or partial absence of the corpus callosum occurs as a birth defect. Agenesis of the corpus callosum (ACC)
occurs when the nerve fibers that make up the corpus callosum do not form, or
form incorrectly (corpus callosum
dysgenesis). You can actually survive if the left and right sides of the
brain are not connected, but you may have various problems over your lifetime.
used to refer to some form of ACC include:
- Partial corpus callosum agenesis
- Hypogenesis of the corpus callosum
- Hypoplasia of the corpus callosum
- Dysgenesis of the corpus callosum
estimated that four out of every 1,000 people have some disorder of the corpus
callosum. ACC is the most common cerebral malformation.
What Causes Corpus Callosum Agenesis?
formation of the corpus callosum, or a partial or malformation of this
structure, is a congenital birth defect. The corpus callosum forms late in the
first trimester of pregnancy. Exposure to certain medications (including valproate,
an epilepsy medication) or toxins (drugs or alcohol) during this period is one
risk factor for the condition. Viral infections like rubella during pregnancy
may result in this condition. Another risk factor is chromosomal damage and abnormalities
like trisomy (having three copies of chromosome 8, 13 or 18). Cysts inside the
brain that block the growth of the corpus callosum can also cause this
of ACC actually occur along with other brain abnormalities. Some of these are
genetic disorders. These usually have a larger impact on brain formation. These
- Arnold-Chiari malformation
- Dandy-Walker syndrome
- Schizencephaly (deep clefts in brain
- Holoprosencephaly (failure to divide
- Hydrocephalus (fluid in the brain)
- Aicardi syndrome
- Andermann syndrome
- Acrocallosal syndrome
Symptoms of Corpus Callosum Agenesis
ACC cases, where there is not significant other brain damage, may not have
dramatic symptoms. Mental retardation is possible, but many individuals have
normal intelligence. Seizures are a common problem in people with ACC.
developmental delays do occur, but may be mild. Developmental delays seen with
ACC include delay in motor skills like sitting, walking, or riding a bike. Poor
coordination is common. Feeding problems and swallowing difficulties may exist.
Some language and speech delays in expressive communication may be noted.
symptoms as a child gets older include:
- vision problems
- hearing impairment
- low muscle tone
- high pain tolerance
- sleep difficulties
- chronic constipation
- social immaturity
- inability to see another’s point of
- poor understanding of social cues
- attention deficit
- obsessive behaviors
- inability to interpret facial
- difficulty with abstract reasoning
- no understanding of slang or idiom
- difficulty separating truth and untruth
How Is Corpus Callosum Agenesis Diagnosed?
ACC can be
found during prenatal scans during an ultrasound. A magnetic resonance imaging
scan (MRI) of the brain may be done on the pregnant mother to confirm
diagnosis. If suspected in an older child, an MRI or computed tomography scan
(CT scan) is performed.
What are Treatments for Corpus Callosum Agenesis?
There is no
cure for ACC. However, the symptoms can be treated successfully. Depending on
the severity of other brain malformations, patients can lead long healthy lives.
Support with medications to control seizures, and physical, speech and
occupational therapy can help.