What Causes Neural Tube Defects in Babies
Neural Tube Defects or NTDs are neurological birth defects that affect the spine, spinal cord, spinal nerves and the brain. It happens early on in the pregnancy around the first month when the ribbon like flat neural tube converts to a tube and if the tube doesn't close fully it causes defects and other complications. The top of the tube forms the brain and the rest of it forms the spinal cord.
Neural Tube Defects Causes
As with most birth defects, doctors and scientisist are not very sure as to what causes these defects, but many believe it to be a combination of genetics, nutritional, environmental and low levels of folic acid before and during pregnancy. Start taking folic acid supplements right from when you are trying to get pregnant, talk to your doctor about it.
Certain medications like anti-seizure, drug and alcohol consumptions, family history of NTDs, obesity, diabetes, and other drug use could also play a role in causing neural tube defects in pregnancy.
Neural Tube Defects Types
Spina Bifida
Spina bifida is the most common NTD, the lower part of the neural tube doesn't close completely during fetal development and that causes three types of spina bifida defects:
Spina Bifida Occulta - The mildest form of NTD, manifests as a gap in the baby's spine but has no external sac or opening on the baby's back and does no damage to the spinal cord or nerves.
Meningocele - Involves a sac of fluid protruding from the baby's back but doesn't have spinal cord as part of the sac.
Myelomeningocele - The most common and complicated type of spina bifida, involves a fluid filled sac with part of spinal cord, nerves, meninges and cerebro spinal fluid protruding from the baby's back.
Encepehlocele
When the upper part of the tube doesnt fully close it causes an opening in the skull leading to a part of the brain and its membrane protruding out through the opening or it could manifest as a small opening in the nasal cavity or the forehead and may not be very noticeable.
Anencephaly
The top of the neural tube does not close leading to a part of the brain, skull and scalp missing or underdeveloped. The brain formed could be exposed as skull and skin might be missing to cover the brain, babies born with this defect are either stillborn or would die shortly after birth.
Iniencephaly
The spine is extremely malformed with a missing neck, skin on the face attached to the chest and with a drastic head tilt to the back. Babies in most if not all cases don't make it beyond pregnancy or are stillborn. Survival is extremely rare in this case.
Neural Tube Defects Symptoms
It affects every baby differently based on the severity and type of the defect. The survival rate also varies drastically based on how bad the defect is like in case of Iniencephaly and Anencephaly. There may be other general symptoms as well
Neurodevelopmental issues like cognitive functioning
Issues with the brain - structural and funtional
Deafness or issues with the hearing
Blindness or issues with the vision
Paralysis or Physical Disabilities
Issues with bowel and bladder control
Neural Tube Defects Diagnosis
During pregnancy doctors do multiple ultrasounds and blood tests to track your baby's development and to look for any abnormalities. Some of the tests for NTDs are
Prenatal Ultrasound
The ultrasound scan during first and second trimester is pretty accurate in spotting any evident NTDs and doctors use this method throughout pregnancy to rule out any anomalies.
Blood Test
Blood tests are commonly used blood at particular milestones in the pregnancy to look for any abberations that point to genetic issues in the baby like NTDs, Down Syndrome, Patau, Edwards and few others based on the levels of certain compounds in blood.
In case of NTD, the level of Alpha Fetoprotein (AFP) in blood which is almost two to three times more or higher than normal points to a possible Neural tube defect. Your doctor may ask for further testing through higher resolution ultrasound and amniocentesis to confirm the same.
Amniocentesis
This tests has its own risks, hence doctors recommend this with caution. A long needle is inserted through the mothers stomach to get a sample of the amniotic fluid to test the cells for any genetic / chromosomal disorders like NTDs.
After birth if the doctor suspects neural tube defect that is not very evident or to look at the extent of the defect, the baby will be checked using X-ray or MRI or CT Scan along with a thorough physical check, looking at urinary stream, movements, and others in the baby.
Neural Tube Defects Treatment
Treatment varies greatly based on the type and severity of the defect, in a few types as mentioned above the baby might be stillborn or die a few hours after birth. In others like spina bifida and encephalocele the doctors assess the situation and recommend surgery / ies to correct the defect to whatever extent.
Surgery is usually done in case of encephalocele to push back the protrution into the skull and seal the opening and in myelomeningocele, to push back the sack into the body. The sac invoves spinal cord, nerves,meninges, and cerebro spinal fluid. In both these cases the surgery is tricky as the sac involves cruicial parts of the body.
Long Term Prognosis
When the Neural Tube Defect is hardly noticeable and doesn't have any manifestations the long term prognosis is good and most children in this case lead normal healthy lives.
Based on the severity and type the neural tube defects affect each child differently. Babies with Anencephaly and Iniencephaly are stillborn or rarely survive past few hours to days after birth.
Some babies with spina bifida and encephalocele may need multiple surgeries, life long care and support, while the others may lead a fairly independent and normal life. Talk to your doctor to understand your options, course of action and treatment based on your child's condition.