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A really good video introduction (6:31 min)
Myelomeningocele
Myelomeningocele (MMC) is the most severe of the three types of spina bifida, involving a failure of neural tube closing—usually at the lower section of the spine—allowing a kind of herniation of the spinal cord and surrounding nerves to protrude out between the vertebrae and through the skin, exposing them to the amniotic fluid in utero.
Incidence is around one in ever 2'500 live briths, and the exact cause is unknown, however research suggests that maternal diabetes, genes, some medications and nutrition may play a role.
Diagnosis
Myelomeningoceles are usually picked up on prenatal ultrasound between weeks 18-20 gestation, and blood tests can pick up the condition as early as 16 weeks. The test screens for maternal alpha-fetoprotein (AFP) in the maternal blood, however this is also present with a number of other conditions also, and process of exclusion will be taken.
If there is a concern of Myelomeningocele through high AFP levels or ultrasound imaging, the mother can undertake further testing, including amniocentesis to sample the amniotic sac to test for markers that indicate whether spina bifida is present, as well as the kind of defect also.
Complications
Chiari malformation ☞ structural defect in posterior skill, allowing brain to settle into upper portion of the neck. Severe cases can cause breathing and swallowing difficulties at birth.
Hydrocephalus ☞ Backup of fluid in the cerebral ventricles requiring surgeries post-birth to drain the excess fluid.
Spinal cord/nerve damage ☞ permanent irreversible damage that may worsen as the pregnancy progresses.
Tethered cord ☞ scarring of the spinal cord.
The higher the defect on the spine, the more severe the complications may present. Other complications may affect:
☞ Bladder/bowel
☞ Cognitive/learning
☞ Breathing & swallowing
☞ Diffficulty walking independently
☞ Orthopaedic conditions such as club foot
☞ sexual dysfunction
☞ Weakness & loss of sensation below defect
Fetal Myelomeningocele Repair
Fetal repair is surgical intervention to significantly reduce the long-term effects of the spina bifida. This can be undertaken between weeks 19-26 of pregnancy.
The mother will recover in hospital for 4-5 days, and weekly follow up and ultrasounds will need to be followed post operative lu for monitoring of maternal and fetal condition.
According to resource, this surgery reduces risk of hydrocephalus by half, increased the child's chances of walking independently, and reversed hindbrain herniation in 9 out of 10 patients.
However it was also found that fetal repair increases risk of premature birth earlier than 37 weeks, problems with future pregnancies, and damage due to the uterus rapturing.
Fetoscopic Myelomeningocele Repair: Less Invasive Option
This option is a less invasive treatment involving keyhole ports in the maternal uterus between weeks 22-26 gestation.
Outlook For Children With Myelomeningocele
This depends on individual factors on a case by case basis, however outcomes tend to be better for babies who receive prenatal surgery, and are delivered close to their due date. Some children will require minimal ongoing care, however unfortunately, others will require medical and educational support for many years.
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