Types of spina bifida
The three main types of spina bifida that are always present at birth are: Spina Bifida Cystica (cyst-like), Spina Bifida Occulta and Encephalocele.
Spina Bifida Cystica
The visible signs of spina bifida cystica are a sac or cyst, rather like a large blister on the back, covered by a thin layer of skin.
There are two forms:
Type one: Myelomeningocele (meningomyelocele)
Myelomeningocele is the most serious and more common of the two forms of cystic spina bifida. Here the cyst not only contains tissue and cerebro-spinal fluid but also nerves and part of the spinal cord. The spinal cord is damaged or not properly developed. As a result, there is always some paralysis and loss of sensation below the damaged region. The amount of disability depends very much on where the spina bifida is, and the amount of affected nerve tissue involved. Bladder and bowel problems occur in most people with myelomeningocele, as the nerves come from the bottom of the spinal cord, so are always below the lesion. It is also necessary to have intact nerve pathways to the brain for complete control and sensation.
Type two: Meningocele
In this form, the sac contains meninges (tissues which cover the brain and spinal cord) and cerebro-spinal fluid, which bathes the central nervous system. Development of the spinal cord may be affected, but impairment is usually less severe than myelomeningocele. Meningocele is the least common form of spina bifida.
Spina Bifida Occulta (hidden form)
This is a mild form of spina bifida, which is very common. Estimates vary but between 5% and 10% of people may have spina bifida occulta. It must be emphasised that, for the vast majority of those affected, having spina bifida occulta is of no consequence whatsoever. Often people only become aware that they have spina bifida occulta after having a back x-ray for an unrelated problem. However, for a few (about 1 in 1,000) there can be associated problems. See Shine’s information sheet on ‘Spina Bifida Occulta’.
This is a sac which is formed when the bones of the skull fail to develop. It may contain only cerebro-spinal fluid or part of the brain may also be present in the sac, resulting in brain damage.
This is where the brain does not develop properly or is absent, and the baby is either still born or dies shortly after birth. Contact Shine for further information.
Most babies born with myelomeningocele also have hydrocephalus (from the Greek hydro, meaning water, and cephalie, meaning brain). This is an accumulation of cerebro-spinal fluid which arises from an imbalance in the production and drainage of that fluid. Further information about hydrocephalus is given in the Shine Information Sheet ‘What is Hydrocephalus?’.