What are they?
During the first few weeks of pregnancy a baby’s brain, spinal cord and its’ coverings develop. The cells that grow to form these structures do so by first forming into a tube - the neural tube. If the tube does not close fully, the opening that is left is called a neural tube defect (NTD).
Normally, the spinal cord and brain are surrounded and cushioned by cerebrospinal fluid (CSF) and are protected by outer layers of tissue called the meninges. The brain is also protected by the skull, and the spinal cord is protected by the backbone (spine), formed by bones called vertebrae. When someone has an NTD, there are one or more gaps in the brain or spinal cord’s protection. This can affect the brain’s development and can leave the spinal cord vulnerable to damage. Because the spinal cord contains the nerves that control body movement, any damage that occurs can paralyse or weaken associated muscles and organs.
The reason why the neural tube may develop incorrectly is not known for sure, but probably involves both genetic and environmental factors.