Theories regarding the causes of hydrancephaly include:
blockage in the carotid artery: some researchers think that a blockage of the carotid artery leads to the under-/no development of the brain. The carotid artery is the most important blood supplier of the brain. With a blockage, the brain barely receives blood. Blood is necessary for development and keeping intact of the brain. inherited condition. infections: during the pregnancy, a woman can develop an infection in the uterus what can lead to problems with the neural tube. environmental toxins: during the pregnancy, a woman can be exposed to environmental toxins what can have effect on the health of the infant. Iniencephaly
Iniencephaly is a rare neural tube defect that results in extreme bending of the head to the spine. The diagnosis can usually be made on antenatal ultrasound scanning, but if not will undoubtedly be made immediately after birth because the head is bent backwards and the face looks upwards. Usually the neck is absent. The skin of the face connects directly to the chest and the scalp connects to the upper back. Individuals with iniencephaly generally die within a few hours after birth. Spina bifida
Spina bifida is further divided into two subclasses, spina bifida cystica and spina bifida occulta. Spina bifida cystica includes meningocele and myelomeningocele. Meningocele is less severe and is characterized by herniation of the meninges, but not the spinal cord, through the opening in the spinal canal. Myelomeningocele involves herniation of the meninges as well as the spinal cord through the opening.
However, due to advances in technology and the ability to diagnose prenatally, the rates at birth are no longer reliable. Measuring the number of cases at birth may be the most practical way, but the most accurate way would be to include stillbirths and live-births. Most studies that calculate prevalence rates only include data from live births and stillborn children and normally exclude the data from abortions and miscarriages. Abortions are a huge contributing factor to the prevalence rates; one study found that in 1986 only a quarter of the pregnancies with an identified NTD were aborted, but that number had already doubled by 1999. Through this data, it is clear that excluding data from abortions could greatly affect the prevalence rates. This could also possibly explain why prevalence rates have appeared to drop. If abortions are not being included in the data but half of the identified cases are being aborted, the data could show that prevalence rates are dropping when they actually are not. However, it is unclear how much of an impact these could have on prevalence rates due to the fact that abortion rates and advances in technology vary greatly by country.There are many maternal factors that also play a role in prevalence rates of NTDs. These factors include things like maternal age and obesity all the way to things like socioeconomic status along with many others.