Causes of bilateral choroid plexus cysts

It is well known that bilateral choroid plexus cysts are pseudocysts. This is a sign that the veins are filled with cerebrospinal fluid. Studies have shown that the reason why bilateral choroid plexus cysts occur in humans is related to the rapid development of the fetal brain primordium compared to the speed of development of the cerebral aqueduct. Once bilateral choroid plexus cysts occur, it will affect the future development of the fetus. So what are the causes of bilateral choroid plexus cysts?

1 What causes choroid plexus cyst?

Choroid plexus cysts are cerebrospinal fluid-filled pseudocysts that appear within the choroid plexus. They are caused by the fact that the rate of cerebrospinal fluid production during the development of the fetal brain primordium is higher than the rate of development of the brain aqueduct. When the production of fetal cerebrospinal fluid is faster than the formation of the aqueduct system in the brain, it will cause a certain degree of cerebrospinal fluid circulation obstruction or formation of choroid plexus cysts. However, the fetus usually forms a brain aqueduct system around 26 weeks. Therefore, once the drainage system is formed, the circulation problem will be solved, the accumulated fluid will gradually disappear, and the cyst will also disappear. If it has not disappeared and is bilateral, the fetus may have chromosomal diseases such as trisomy 21 or trisomy 18, and amniocentesis or cord blood puncture is needed to rule out chromosomal abnormalities.

2 Choroid plexus cyst formation process

The choroid plexus is a structure rich in blood vessels. It is formed by the growth of pia mater blood vessels into the ventricles and the bulge of the ventricular membrane epithelium into the ventricles. It is the main structure for producing cerebrospinal fluid and is formed at 7 weeks of gestation. In early pregnancy (10-12 weeks), the choroid plexus occupies almost the entire lateral ventricle, but then quickly shrinks. During the second trimester of pregnancy, approximately 1-2% of fetuses may be diagnosed with choroid plexus cysts. During the 19th to 28th week of pregnancy, the loose choroid villi of the choroid plexus will gradually be replaced by dense connective tissue, and the tumor-like capillary network will be replaced by a well-differentiated wavy folded structure. Therefore, most choroid plexus cysts can disappear or shrink before 28 weeks. Only a few cysts will not disappear and will continue to grow.

3 How is a choroid plexus cyst diagnosed?

Fetal choroid plexus cysts are diagnosed by ultrasound. Diagnostic basis: Most cases use the presence of a clearly defined anechoic area with a diameter > 2 mm within the choroid plexus as the diagnosis standard. Choroid plexus cysts can be seen on ultrasound after 10 weeks of pregnancy. It manifests as a cystic and anechoic cyst in the hyperechoic choroid plexus, with thin walls, smooth and neat edges, and is mostly round. The cyst can be solitary or multiple; it can be unilateral or bilateral; it can be a simple cyst or a multi-chamber cyst with septa.

4 How to treat choroid plexus cyst

If the fetus has a simple isolated choroid plexus cyst, no special treatment is required, because such a cyst will gradually disappear. The expectant mother only needs to have an ultrasound check every 2 to 3 weeks to dynamically observe the changes in the cyst until delivery. In addition, follow-up should be strengthened for babies in childhood to monitor their neurological development. If the fetus has bilateral cysts or complex choroid plexus cysts, the fetus may have chromosomal abnormalities or other malformations. In this case, the expectant mother needs to undergo amniocentesis or cord blood puncture under the doctor's advice to confirm whether there is any abnormality, and then formulate a subsequent intervention plan based on the puncture results. Termination of pregnancy is usually recommended.