Definition and Overview
Meningomyelocele is the most severe type of spina bifida, a congenital defect that occurs when the backbone and spinal canal fail to close before the baby is born. It is a neural tube defect and is the most common permanently disabling birth defect in the United States.
Spina bifida, which translates to “split spine”, has different types that are categorised based on their severity. These include:
Spina bifida occulta - The most common and mildest form that affects about 5% of the population. But many remain undiagnosed because the condition is normally asymptomatic and has minimal to zero effects on body functions.
Meningocele - A rare form of spina bifida caused by a single developmental defect that leads to the herniation of the meninges between the vertebrae. The condition is characterised by a spinal fluid-filled sac on the newborn’s spinal column. Although patients with this condition typically do not suffer from nerve damage, many have minor disabilities.
Meningomyelocele or myelomeningocele - The most serious type that results in most severe complications. It occurs when the spinal column fails to fuse causing the spinal cord and meningeal membranes to protrude through an opening. Patients with this condition have a sac on their lower back containing spinal elements including nerve roots, parts of the spinal cord, meninges, and cerebrospinal fluid.
Causes of Condition
The exact causes of spina bifida are unknown but environmental and genetic factors are thought to play a role in its development. A baby’s risk of developing the condition is higher if their mother is:
Taking antiseizure medications
Folic acid deficient
Also, those who have siblings with spina bifida have a 4% chance of developing the condition. However, in many cases, there is no family connection.
Babies with meningomyelocele are born with an exposed spinal cord or a sac that covers the spinal cord. They normally suffer from severe symptoms caused by an underdeveloped spinal cord and require lifelong treatment. Symptoms include:
Structural defects in the part of the brain that controls balance
Tethered spinal cord
Mild to life-threatening latex allergy
As they grow older, patients exhibit:
Lower limb paralysis or poor ability to walk
Problems with bowel or bladder control
In youth with spina bifida, difficulties with executive functions have been noted. Unlike typically developing children, patients do not display improvement in their executive functioning as they grow older. They normally have problems with organising, planning, initiating, and working memory. They also struggle with abstraction, problem-solving, and have poor cognitive flexibility.
If the lesion is high up in the spine, the patient will not be able to move their legs and will require a wheelchair for life. However, if there is sensation below the knees, there is a possibility that the patient will walk with the aid of orthopaedic braces.
Patients with spina bifida and hydrocephalus often display attention problems with up to 31% developing attention deficit hyperactive disorder (ADHD) at a very early age.
Who to See and Types of Treatments Available
Pregnant women typically undergo a series of tests throughout their pregnancy to check the condition of their unborn child. One of these tests is foetal ultrasound. If this test shows a higher than normal levels of maternal alpha-fetoprotein (AFP), doctors will perform a quadruple screen, a blood test that screens for chromosomal abnormalities (such as Down syndrome) and neural tube defects, including spina bifida. It is performed between 15 and 20 weeks of pregnancy. If the results suggest the presence of spina bifida, amniocentesis and ultrasound of the foetal spine are performed. Due to the severe symptoms associated with spina bifida meningomyelocele, many women opt to terminate their pregnancy.
Babies born with meningomyelocele spina bifida undergo surgery after delivery. The goal of the procedure is not to cure nerve damage but to prevent further damage to the nervous tissue, to close the opening on the back, and to prevent infection such as bacterial meningitis. During the procedure, the spinal cord is moved inside the spine and covered with meninges. A shunt is also usually installed to drain excess cerebrospinal fluid to reduce pressure.
In some cases, treatment of spina bifida during pregnancy is performed. Although this is a riskier option, it is sometimes necessary. The procedure, which increases the risk of preterm birth and permanent scarring of the uterus, can be performed using traditional method (open foetal surgery) or via fetoscopy. The latter results in far less surgical trauma for both the mother and the foetus as it does not require large incisions in the abdomen and uterus.
Despite undergoing surgery, patients with meningomyelocele are highly unlikely to develop bladder control and they typically need to wear orthopaedic braces to support their legs. They require lifelong treatment and have to work with a number of specialists throughout their lives. These include orthopaedists, psychiatrists, neurosurgeons, neurologists, physical and occupational therapists, and speech pathologists, among others. As they grow older, patients are taught self-catheterisation so they are able to manage their bowel and bladder output.
The short and long-term outlook for patients with meningomyelocele depends on the exact location of the damage (either lumbar meningomyelocele or cervical meningomyelocele), the size of the lesion, how soon treatment was given, type of treatment, and the presence of other medical conditions.
Kondo, A; Kamihira, O; Ozawa, H (January 2009). "Neural tube defects: prevalence, etiology and prevention.". International Journal of Urology. 16 (1): 49–57.
Sandler, AD (August 2010). "Children with spina bifida: key clinical issues.". Pediatric Clinics of North America. 57 (4): 879–92.