FETAL NEURAL AXIS PART II (Chapter 60)

* Begins to develop at 8 weeks of gestation.
* Is not complete until 18 - 19 weeks.
The cause is unclear.
* Thought to involve vascular disruption or inflammatory lesion before 12 weeks.

Begins to develop at 8 weeks of gestation.

Is not complete until 18 - 19 weeks.
What is the cause of agenesis (ACC)?

The cause is unclear.
* Thought to involve vascular disruption or inflammatory lesion before 12 weeks.

A fibrous white matter tract that connects the cerebral hemispheres and aids in the cognition and neurological functions.

Range of complete to partial absence of callosal fibers that cross the midline, forming a connection between the two hemispheres.

Callosal agenesis

Occurs sporadically

May be associated with other CNS malformations:
- Hydrocephalus
- gyral anomalies
- Heterotopias
- DWM
- holoprosencephaly

May be transmitted in autosomal-dominant or autosomal-recessive manner.

X-linked syndromes have been idenified.

- Trisomies 21
- Trisomies 13
- Trisomies 18
- Triploidy.

-Aicardi
- Apert
-Opitz
- Joubert
And others.

Prognosis depends on high incidence of associated anomalies; may carry poor prognosis.

False

Agenesis of the Corpus Callosum (ACC) may be asymptomatic or associated with mental retardation and/or seizures.

Sonographic features:
* Absence of corpus callosum
* Elevation and dilation of third ventricle
* Widely separated lateral ventricular frontal horns with medial indentation of medial walls
* Dilated occipital horns ( colpocephaly ), giving lateral ventricles teardrop shape
* Absence of cavum septum pellucidum