What Is Choroid Plexus Cyst: Its Causes And How To Treat It?

Choroid plexus is made up of spongy cells and blood vessels in a tiny space called ventricles in the brain. It produces cerebrospinal fluid which flows around the brain and spinal cord. The main function of cerebrospinal fluid is to act as a cushion and protect the brain.

Many times the fluid gets trapped and forms pocket or blister or bubble. These fluid filled pockets are called choroid plexus cysts (CPC). They are detected on ultrasound performed in pregnant women. CPC are generally considered to be a normal phenomenon. Their incidence ranges from 1% to 3% in pregnant women.

Often it is an incidental finding observed on sonography between 12 week and 22 week of pregnancy. The cyst can be present in right as well as left ventricle or only in one ventricle.

A choroid plexus cyst usually is not a cause of concern and it regresses spontaneously during the last months of pregnancy. However, in some cases it may be associated with a chromosomal problem such as trisomy 18. It can also indicate other genetic problems.

What Causes Choroid Plexus Cyst?

Choroid plexus cyst is present in 1 to 3 % of normal fetus.

The epithelial cellular lining of the choroid plexus may fold abnormally and trap the cerebrospinal fluid during the development of the fetus. These trapped pockets form choroid plexus cysts. They form between 12 and 22 weeks. Most of the time it is incidentally visualized in pregnant women while performing sonography. The exact cause for its formation is not known. There can be a single cyst or multiple cysts. Their size can vary. Besides fetuses, it is believed that many adults may also have tiny choroid plexus cysts.

Choroid plexus cyst on its own may not have an impact on the health of fetus, its growth and development or learning after the birth of the fetus. However, in small number of fetuses, choroid plexus cyst may be a marker for genetic disorder called trisomy 18. It is a rare chromosomal disorder, where there is an extra copy of chromosome 18.

Fetus having trisomy 18 does not survive for a long time. Most of them are stillborn. If they are born they are mentally retarded. They also have heart, brain and kidney defect. Invariably, fetuses with trisomy 18 will have choroid plexus cyst. But at the same time, it needs to be mentioned that all cases of CPC are not tirsomy 18 cases, in fact most of them are normal. On sonography, there are other findings too besides choroid plexus cysts which distinctly demonstrate tirsomy 18.

Treatment For Choroid Plexus Cysts

What is the concern if there is choroid plexus cyst?

Precisely it is very difficult to rate the risk of tirsomy 18 defect in a fetus having CPC. However, apart from choroid plexus cyst on sonogram, if there is no other abnormality detected than in 99 percent cases, the fetus may be considered normal.

The risk of tirsomy 18 further reduces when test called alpha fetoprotein (AFP) is found to be normal. Amniocentasis will reveal chromosomal defect, but as it has great risk of miscarriage it is performed with precaution and in selected cases where the benefits of the procedure outweighs the risk factor.

In 99% of fetuses, choroid plexus cyst resolves or disappears after 28 weeks of gestation. Once the cyst disappears, there is no second chance of its appearance. In rare instances a large choroidal cyst may block the cerebrospinal flow. Such cases may require treatment after the fetus is born.

To rule out trisomy 18, sonogram, AFP test and finally amniocentesis are valuable. However, the patient should have knowledge that amniocentesis has miscarriage as one of its complication.