Spina bifida literally means ‘split spine’. A fault in the development of the spinal cord and surrounding bones (vertebrae) can leave a gap or split in the spine. The spinal cord does not form properly, and may also be damaged. To help understand what spina bifida is, it is useful to explain the composition of the nervous system.
The central nervous system consists of the brain and the spinal cord. Everything we do, is controlled by the brain, including breathing and maintaining our body temperature. Our senses send information to our brain, which deliver messages to different parts of the body via the spinal cord and pairs of nerves that emerge at each vertebra.
The spine is made up of 33 bones or vertebrae. The vertebrae have two main functions - to protect our spinal cord, and to provide anchorage to our muscles.
The central nervous system and spine develop very early in the pregnancy, between the 14th and 23rd day after conception. Spina bifida occurs when the neural tube, the structure in the embryo that becomes the brain and spinal cord, fails to close correctly. The vertebrae also fail to form complete rings around the affected portion of the spinal cord. This leaves a gap at the back, involving one or more vertebrae, most commonly around waist-level.
Open spina bifida, is usually detected at the antenatal mid-term ultrasound (20 week) scan. The appearance of the skull bones and cerebellum - part of the back of the brain - show distinct signs that lead the sonographer to look for tiny changes in the spine. For example, the bones to the sides of the head can look pinched, and the cerebellum looks long, thin and wrapped around the spinal cord, instead of being round (Chiari II).
Closed spinal lesions such as lipomyelomeningocele are often not detected at the antenatal mid-term ultrasound scan: the brain and skull will usually look normal so the changes to the spine may not be detected. Often people only become aware that they have it after having a back x-ray for an unrelated problem.
Most commonly the baby will be seen by a paediatric neurosurgeon shortly after birth. The surgeon will then decide whether the baby should have surgery to repair the defect in the back: this surgery will take place in a specialist unit usually within 48 hours. Sometimes, in large lesions or premature babies, there may not be enough skin available to close the lesion right away, and the Plastic Surgery Team may be involved.
It may be possible, under certain circumstances, to operate on the baby’s lesion in the womb, before 26 weeks of pregnancy. See Shine’s information on prenatal surgery, and talk to your Fetal Medicine clinicians urgently if you are pregnant and would like to know more.
These vary greatly. Even people with a lesion of similar size and position may experience different impairments to varying degrees. Generally, people with lesions at waist level (L1 or above) will use wheelchairs full-time, while most people with lesions at the bottom of the spine (sacral) will be able to walk as adults.
Many children with lesions in the mid lumbar area walk during childhood, but choose to use a wheelchair for longer distances, sports, or as they get older. Splints often help support the feet and ankles.
Loss of skin sensation can lead to sores, especially on the feet, through injury or shoes that rub, and sometimes burns to the feet and legs are also common. It’s important to protect the feet, by having correctly fitting shoes or splints, covering hot pipes and carefully checking the bathwater before getting in.
Bladder and bowels are very often affected, even in people with sacral lesions. Loss of sensation, and lack of coordination between the bladder muscle and the outlet (bladder neck) can lead to difficulty filling and emptying the bladder. Infections, leaking and frequency of passing urine can occur, but intermittent catheterisation, and medication to relax the bladder can be a big help. Bowel issues such as constipation or leakage can often be helped with irrigation and/or medication.
Because spina bifida changes the way the brain develops, there can be an impact on learning and behaviour.
NB Children with spina bifida should have their childhood vaccinations just like other children.
Prospective parents who have had a baby with a neural tube defect, or who have a close relative with a neural tube defect, should be referred to a genetic counsellor for advice. This referral can be made through a GP.
At present we don’t know exactly why spina bifida develops, and research continues.
However, we do know that taking folic acid supplements before getting pregnant can reduce the risk of spina bifida in unborn babies. For families with no history of spina bifida the Department of Health recommends women take an ‘over the counter’ dose of 400mcg daily. For families where there is a history of spina bifida, or other neural tube defects, a prescription dose (5mg) of folic acid is needed.
Folic acid should be taken daily for at least 8 weeks prior to conception and through to the 12th week of pregnancy.
The exact reasons why the neural tube develops incorrectly are not yet known but it is probably connected with both genetic and environmental factors are known to contribute. Shine also recommends taking a supplement of B12 (2.5mcg or more) for three months before pregnancy. For more information, please visit www.folicforlife.com
You may not know, but there are a number of different types of spina bifida. We’ve listed them here along with an explanation of what each one means.
Reviewed 31/03/21
