Meningocele

What is Meningocele?

A simple meningocele is a condition where the protective membranes around the brain and spinal cord, known as meninges, and some spinal fluid bulge into the soft tissue under the skin through a defect in the spine. The skin usually stays intact in these cases. A complex meningocele is related to other spine abnormalities. Usually, meningocele does not cause any symptoms and is not linked to any urgent nerve-related conditions. These types of spinal defects are the second most common birth defect, coming only after heart defects.

These defects can be classified into two main types: open or closed. The condition known as spinal dysraphism is a range of birth defects caused by problems in the development of the spinal arch, the bone structure that protects the spinal cord. This can result in the meninges or other spinal elements being pushed out through gaps, leading to a variety of clinical symptoms. Spinal dysraphism can be further categorized into aperta, where the lesion is visible, and occulta, where the lesion is not visible from the outside. Other terms based on what is found during medical examination include meningocele, myelomeningocele, lipomeningomyelocele, rachischisis, and myeloschisis. Myelomeningocele is the most common type, making up 90% of cases.

What Causes Meningocele?

The exact cause of meningocele, a type of birth defect that affects the protective membranes around the spinal cord, is not well known. There are several factors that might play a role. Most often, a deficiency in folate, a type of vitamin B, seems to be a common cause. This could be because a person isn’t consuming enough folate through their diet, is taking certain medications that hinder folate absorption, or has specific genetic factors that affect how their body uses folate. Meningocele can also be associated with chromosomal issues or single-gene disorders.

There are some genetic syndromes, including HARD (which involves issues with the brain’s fluid-filled structures, brain development and retina), Meckel-Gruber syndrome, and trisomy 13 or 18, that are known to be linked with meningocele.

Certain factors that relate to the mother can increase the chances of this defect. This includes being of an older or younger than average maternal age, having a low socioeconomic status, consuming alcohol, smoking, using caffeine, being overweight, having a diet rich in high-glycemic-index foods, or having gestational diabetes during pregnancy. Additionally, the use of certain anti-seizure medications during pregnancy, such as valproic acid and carbamazepine, can increase the chances of this defect. Amniotic bands, strands of amniotic fluid that can wrap around and constrict parts of the fetus, can also interfere with normal neural tube development.

Another factor that may be associated with meningocele is a raise in the mother’s core body temperature in early pregnancy due to fever or other causes. Environmental factors, such as certain chemicals used in farming and a group of chemicals known as polycyclic aromatic hydrocarbons, can also potentially lead to neural tube defects.

Risk Factors and Frequency for Meningocele

Neural tube defects, which are birth defects related to the brain and spinal cord, affect a range of 1.0 to 10.0 per 1,000 births worldwide. The rate is slightly lower in the USA and many European countries, with roughly 0.5 to 0.8 cases per 1,000 births. If a family has a baby with a neural tube defect, the chance of this happening again in future pregnancies is up to 5%. The frequency of these defects can change based on factors like location, ethnicity, gender, and which country you’re in. It happens more often in Whites as compared to Blacks, and in females compared to males. Additionally, some racial or ethnic groups such as the Irish and Mexican face a higher risk than others like Whites and Asians.

Signs and Symptoms of Meningocele

Prenatal screening for neurological defects involves two main tests: measuring the alpha-fetoprotein level in the mother’s blood and using an ultrasound during the second trimester to check for any abnormalities in the developing baby. Notably, a condition called meningocele can be observed at birth through a noticeable swelling covered with skin at the back of the baby. The location of the defect can be in various areas, including the thoracolumbar, lumbosacral, lumbar, thoracic, sacral, and cervical regions. Generally, individuals with meningocele don’t exhibit significant neurological symptoms. During a clinical examination, a mass that can be seen when light passes through it (transilluminates) is often present at the midline of the back.

Just after the baby is born, a comprehensive assessment needs to be carried out. This involves detailed examinations of various parts of the newborn’s body, including their head, neck, and skull bones. A full neurological examination is also performed immediately at birth to detect any potential abnormalities. Lastly, symptoms of thoracic meningocele can vary depending on the size of the meningocele and how close it is to surrounding structures. Symptoms can include back pain, breathlessness, coughing, and fluttering sensations in the chest if the lung and mediastinal structures are compressed.

• Initial prenatal screening for neurological defects involves measuring maternal serum alpha-fetoprotein levels and high-quality second-trimester ultrasounds
• Meningocele often presents as a noticeable swelling covered with skin on the baby’s back at birth
• Anomalies can form in the thoracolumbar, lumbosacral, lumbar, thoracic, sacral, and cervical regions
• Clinically, a mass that’s often present can be seen when light passes through it (transilluminates)
• Comprehensive assessment involves examination of the newborn’s head, neck and skull bones, and a full neurological examination
• Symptoms of thoracic meningocele vary and can include back pain, breathlessness, coughing, and chest disturbances.

Testing for Meningocele

After a baby is born, it is essential to perform specific imaging tests based on their health. Plain X-rays are commonly used to check for any abnormalities in the skull, bones, or spine. For detailed examination of the baby’s nerve tissue and to screen for a condition termed hydrocephalus (a buildup of fluid in the brain), a Magnetic Resonance Imaging (MRI) scan is often considered the best diagnostic tool. Ultrasonography, which uses soundwaves to create images, might also be used for a fast check-up for hydrocephalus. A surgical team should always be kept ready to determine if the baby needs immediate surgery.

Treatment Options for Meningocele

Managing meningocele, a type of birth defect where the spinal cord doesn’t close all the way, requires a team approach. When first diagnosed, it’s crucial that doctors explain to the family the immediate and potential long-term effects of the condition and any treatments.

When a large meningocele is present, it is usually best to operate as soon as possible. If there’s a risk of an infection in the brain or spinal cord (meningitis), doctors will typically start treatment with preventative antibiotics and medications to control seizures (anticonvulsants). These newborn patients need to stay in a special part of the hospital for newborn care (the neo-natal intensive care unit) where their blood electrolytes and counts can be closely watched. Doctors may also prepare for a possible blood transfusion by matching the baby’s blood type with potential donors.

A meningocele can often come along with another problem called tethered cord syndrome, where the spinal cord is improperly attached within the spine. An MRI, a type of imaging scan, can help confirm the diagnosis of meningocele. Once the diagnosis is confirmed, doctors usually recommend surgery to repair the meningocele. During the operation, the surgeon will inspect the spinal canal and, if necessary, untether or release the spinal cord after the meningocele has been repaired.

What else can Meningocele be?

Encephalocele is a condition where brain tissue protrudes through a defect in the skull. This can result in masses in a child’s nasal cavity, causing breathing problems. These masses, known as menigocephaloceles or meningoceles, are often mistakenly diagnosed as polyps or tumors. If these misunderstood hernias are improperly treated, it can lead to further complications such as meningitis or a leakage of fluid due to accidental cutting or puncturing.

Doctors use MRI scans, which are a safe and completely non-invasive imaging technique, to accurately diagnose menigocephaloceles and meningoceles. It’s worth noting that Noonan syndrome and lateral meningocele syndrome share some similar facial attributes. For instance, indicators of lateral meningocele syndrome might include:

• Arched eyebrows
• Drooping eyelids (also known as ptosis)
• A flat, concave face
• A thin upper lip
• Ears that are low-set and angled backwards
• A low hairline at the back of the head
• Wide and short ends on the second and third fingers (also described as pseudo-clubbing)

What to expect with Meningocele

Meningocele typically does not involve the nerves and usually presents no sudden nerve-related complications. Therefore, it usually has a favorable outcome. Spina bifida aperta, on the other hand, is often characterized by a skin defect and carries the risk of cerebrospinal fluid (CSF) – the fluid that surrounds the brain and spinal cord – leaking out. However, concealed forms of spina bifida do not show any visible skin openings.

Interestingly, the prevalence of spina bifida at birth has seen a significant drop of 23% over a decade, from 1995 to 2004. This change came after the Food and Drug Administration, the body in charge of food safety, ordered that all cereal and grain products be fortified with folic acid. This vital nutrient plays a crucial role in ensuring the healthy development of the spine.

In the medical field, patients with meningocele generally have an excellent outcome, and in most cases, a straightforward surgical repair is all that’s needed to address their condition.

Possible Complications When Diagnosed with Meningocele

When a meningocele, a type of spinal defect, is compressed, it can lead to symptoms of increased pressure within the skull. This is because the compression shoves extra spinal fluid into the skull cavity. High pressure inside the skull can make the base of the skull wear away, which can lead to a leakage of brain and spinal fluid. Recent studies suggest that meningocele often goes hand in hand with a condition called tethered cord syndrome. Many children who have had their meningocele repaired have shown symptoms of tethered cord syndrome. A related spinal defect known as myelomeningocele is often connected with a condition called hydrocephalus, a build-up of fluid in the brain.

Common Symptoms:

• Increase in skull pressure
• Erosion at the base of the skull
• Leakage of brain and spinal fluid
• Signs of tethered cord syndrome in children who had meningocele repair
• Hydrocephalus in cases of myelomeningocele

Preventing Meningocele

Over the past three decades, there has been a significant reduction in the number of cases of neural tube defects (abnormalities in the brain, spine, or spinal cord). This reduction is thanks to better ultrasound imaging technologies which now allow us to examine a baby’s development inside the womb much more clearly. Other factors contributing to this decrease include medical tests such as serum alpha-fetoprotein measurements (a test that detect protein made by the unborn baby), the option of ending pregnancies where these defects are present, and the intake of folic acid supplements by women of childbearing age.

However, mothers who have diabetes, obesity, or have had high body temperature, as well as those who consume substances like medications that affect folic acid, excess vitamin A, cigarettes, and alcohol during pregnancy, and those who take antiseizure medications like valproate and carbamazepine, are at an increased risk of giving birth to children with neural tube defects. As such, healthcare professionals often recommend giving a higher dose of folic acid supplements (4 mg) to these high-risk mothers. It’s also common practice to check for neurological abnormalities in unborn babies using an ultrasound, guided by the maternal alpha-fetoprotein screening results. This screening typically occurs around the 12th, 22nd, and 32nd weeks of pregnancy.