- What is Spina Bifida?
- Risk Factors
- Clinical Examination
- How is it Diagnosed
What is Spina Bifida?
Spina Bifida refers to a birth defect resulting in malformations of the spinal cord, caused by the incomplete closure of a vertebral arch during development. It forms a part of the broad complex known as neural tube defects which refers to malformation of the neural tube during embryogenesis. There are three categories of spina bifida: spina bifida occulta, spina bifida cystica (myelomeningocele) and meningocele.
It may result in the exposure of the meninges (spinal membranes) and spinal cord.
Spina bifida Occulta is a mild form of spina bifida. There is no opening on the back however the outer part of some of the vertebrae are not completely closed – this split is so small that the spinal cord does not protrude. The skin at the site of the lesion may be normal, have some hairs growing from it, have a dimple in the skin, or a birthmark. Spina Bifida Occulta is associated with mild forms of incontinence, slight ambulatory problems, and slight loss of sensation.
Spina Bifida Cystica is the most serious form of Spina Bifida and it refers to the meninges and spinal cord protruding through a cleft. The spinal cord is usually damaged and has not developed properly. This is usually associated with paralysis and loss of sensation below the level of the lesion.
Meningocele is the least common form of Spina Bifida. The outer part of some of the vertebrae are split and the meninges are usually damaged and pushed out through an opening. The nerves are not badly damaged and hence there is little disability.
In general, the systems affected may include the neurological, musculoskeletal, renal/urologic and skin/exocrine system.
The total incidence of neural tube defects is approximately 1 in 700 live births in Caucasian people. The incidence amongst African-Americans is less than 1 in 3000 live births.
Spina Bifida is a congenital abnormality and is usually evident at birth. There is no particular predominance for male or female newborns.
- Maternal folic acid deficiency has a strong correlation with neural tube defects.
- Maternal use of valproate in the 1st trimester may be associated with spina bifida, however the risk of epilepsy in pregnancy outweighs not using medication in most cases.
- Previous children with spina bifida is associated with an increased risk of spia bifida – this suggests there may be some genetic component to this disease (in the absence of ongoing environmental factors).
- It should be noted that over ninety percent of cases of spina bifida, the pregnancy is classified ‘low risk’.
Spina Bifida can result in varying degrees of paralysis, loss of sensation, incontinence, spine and limb problems and in some cases cognitive impairment. However it should be noted that more than eighty percent of patients with Spina Bifida have a normal IQ.
Early problems that may occur predominantly involve infection at the source of the lesion. The infection may spread to the central nervous system if left untreated.
The spinal cord may also tether causing further neurological deterioration.
It may also be associated with other problems such as hydrocephalus (extra fluid around the skull resulting in a large head) and latex allergy.
How is it Diagnosed
No general investigation is usually necessary as the diagnosis of spina bifida is usually made on clinical grounds.
Tests can be done early in the pregnancy to try and assess the risk of a neural tube defect and this is usually done at 11-13 weeks.
The prognosis of spina bifida has greatly improved thanks to advances in multidiscplinary care. Depending on the degree of disability, including paralysis, incontinence and the loss of sensation, spina bifida can be effectively managed in many cases.
Treatment for spina bifida is usually done with a multidisciplinary approach. This usually involves paediatric neurosurgery, orthopaedics, urology, nursing, social services, paediatrics and physical therapy.
If required, spina bifida defects are repaired surgically within the first few days of life. A brain shunt may be required to drain fluid and emergency surgery may be required if here are signs of brain or nervous system compression.
Patients should be taught appropriate bowel and bladder exercises in order to help with any incontinence.
The amount of disability a patient experiences should be minimised by physical therapy and multidisciplinary care.
Patient education on areas such as diet (obesity is a major cause of morbidity in patients with spina bifida), and genetic counselling if required.