Corpus callosum dysplasia

Introduction The human brain is divided into two hemispheres, and the left and right hemispheres are connected by a number of nerve fibers, the largest of which is called the corpus callosum. The corpus callosum begins to develop as the embryo develops to 12 weeks of age and is formed at 17 to 20 weeks of fetal life. During this period, many factors can cause the development of the carcass to be affected, and the result is the so-called carcass dysplasia. Among children with normal development, the chances of developing dysplasia are very low, but for children with developmental disabilities, the incidence can be as high as two out of every 100 people.

Cause

Carcass development process:

At the 7th to 10th week of the embryo, the dorsal side of the endplate is generally thickened, and a joint block is formed above it, which induces the growth of the cerebral hemispherical axons from one side to the other to form a corpus callosum. At the 74th day of the embryo, the earliest corpus callosum fibers were seen on the embryo, and the corpus callosum matured at 115 days. The corpus callosum is divided into four parts: the mouth, the knee, the body and the pressure. The development sequence is from front to back, just opposite to the maturity order. If the joint block does not induce axons to cross the midline from the cerebral hemisphere side to the contralateral cerebral hemisphere, the corpus callosum cannot form.

Possible causes of dysplasia:

Early intrauterine infection, ischemia and other causes can cause dysplasia in the anterior part of the brain, and corpus callosum is lost. Late lesions can cause dysplasia of the corpus callosum. Usually the body and the knee are involved first, but also the knee and the pressure part are involved at the same time, but the knee is only involved in the knee, and only in the forebrain without cracks. However, Barkovich (1988) believes that dysplasia of the corpus callosum is due to impaired precursory stage of corpus callosum formation and does not occur during carcass formation. Carcass dysplasia also has a genetic basis.

The causes of dysplasia include the following factors:

(1) Toxicity - metabolic factors, such as maternal alcoholism or diabetes during pregnancy, the fetus itself suffers from certain metabolic diseases.

(2) Chromosomal abnormalities, the most common being trisomy 8 or trisomy 18.

(3) Gene abnormalities or certain special syndromes (such as Aicardi's syndrome) are inherited by dominant, recessive or sexual inheritance.

(4) The brain of the fetus is infected at the beginning of pregnancy.

an examination

Related inspection

Blood routine brain CT examination

Its clinical symptoms and signs are related to the combined other brain malformations, because congenital corpus callosum hypoplasia or lack of itself generally does not produce symptoms. In adult patients, using complex psychometric examination methods, it can be found that there are slight obstacles to the information transmission in the two hemispheres. Neonatal or infant patients can be characterized by spherical head, wide eye distance and giant brain malformation. Most of the features of corpus callosum dysplasia or absent are found in CT scans of suspected hydrocephalus. Mild mental retardation or mild visual impairment or cross-tactile localization disorder may occur. In severe cases, mental retardation and epilepsy may occur. Increased intracranial pressure can occur due to hydrocephalus. Infants often have sputum status and pyramidal tract signs. X-4 sexual hereditary, characterized by seizures for several hours after birth, and severe developmental delay.

Carcass hypoplasia can be divided into all or part of the lack of, often combined with other brain developmental abnormalities, or part of other syndromes. Common malformations of the merger include: Chiari type II, Dandy-walker malformation, intracerebral cyst, neurological migration disorder (common gray matter ectopic and cerebral palsy), brain swelling or facial midline deformity, cingulate gyrus and transparent septum. Hydrocephalus and small brain deformities. Simple carcass hypoplasia has no obvious symptoms, most of which are found in adulthood and childhood. If accompanied by other malformations, symptoms often occur, such as mental retardation and epilepsy. The performance of CT and MRI are:

1. The longitudinal fissure is close to the anterior part of the third ventricle (the longitudinal fissure of the embryonic stage is connected with the transparent compartment, and is closed by the corpus callosum. If the mouth is not developed, the longitudinal fissure communicates with the transparent compartment and directly reaches the front of the third ventricle. At the latest, regardless of the dysplasia or dysplasia of the corpus callosum, the longitudinal part of the corpus callosum is the most common manifestation.

2, all or part of the corpus callosum is absent, and some of the deficiencies often occur in the corpus callosum. Hippocampus, lack of anterior or posterior commissure.

3. The anterior horn of the lateral ventricle is displaced outward, and the lateral side of the lateral ventricle has a depressed impression. The reason is that the front corpus callosum that originally connected the hemispheres on both sides is absent. The fibers that originally connected the hemispheres on both sides of the hemisphere are now arranged longitudinally, located at the inner edge of the lateral ventricle, compressing the lateral ventricles, forming an impression. The anterior horns of the ventricles on both sides of the deformity are separated from each other to form a batwing shape.

4, lateral ventricle body separation, parallel to each other, mainly seen in the cross-sectional image, may be the only manifestation of mild carcass hypoplasia.

5, the body part of the body is absent, so that the side chamber triangle area is enlarged.

6. The sulcus on the inner side of the cerebral hemisphere is radially arranged (on the sagittal image).

7. The hippocampus is underdeveloped, leading to an enlargement of the lateral coma. Deep white matter dysplasia is also the cause of lateral ventricular enlargement.

8. The third ventricle is elevated in position and expands in a saclike manner, separating the internal cerebral veins on both sides.

9. A large cyst is formed in the longitudinal fissure between the hemispheres on both sides. The cyst and the third ventricle are separated, with or without traffic between the lateral ventricles. The cyst can be located only on one side of the cerebral palsy, or across the brain, on both sides of the cerebral palsy.

10, the corpus callosum can be combined with lipoma, lipoma can also extend to all parts of the corpus callosum.

Differential diagnosis

Differential diagnosis

Sella deformation: empty saddle is the subarachnoid space from the saddle septum and the pituitary stalk at the junction of the saddle, which is filled with cerebrospinal fluid, so that the saddle enlargement deformation, pituitary compression and flattening. (empty sella syndrome, ESS) refers to syndromes in which the sella is enlarged and the pituitary tissue is squeezed, including headache, visual impairment, cerebrospinal fluid rhinorrhea, endocrine dysfunction, hypertension, obesity, etc.

Increase and absorption of the sella: more common in pituitary tumors, craniopharyngioma, meningioma, pituitary adenocarcinoma and increased intracranial pressure caused by various reasons.

Sella deformation: craniopharyngioma often shortens the saddle flattened saddle back, and the optic tract glioma makes the sella a gourd shape; the parasagittal tumor can cause a "bilateral" sign at the bottom of the saddle.

Calcium calcification shift: Pineal calcification is common in adults and is more likely to occur with age. About 75% of normal adults show pineal calcification on CT scans. The diameter is usually in the range of 3 to 5 mm, but sometimes it may be more extensive. The pineal calcification area is large and displaced, and it appears in children. It should be considered whether there is a possibility of tumor in the pineal region.

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