Introduction

Lipomyelomeningocele (LMMC) is a type of spina bifida birth defect that affects the lumbar region of the spine and is characterised by a swelling of fat in the lower back. It is generally not considered to be life threatening provided the treatments are suitable for the patient, although additional conditions may arise such as urinary tract infections (UTIs) or other spina bifida which must be acknowledged before treatment.¹ Screening for LMMC can typically be achieved with magnetic resonance imaging (MRI) but other methods may need to be considered depending on patient needs. Lumbar punctures are also considered to assess cerebrospinal fluid, all before surgical interventions are considered. Like all surgery involving the central nervous system, it is highly complicated, and a single procedure is unlikely to solve the issue. Patients must be closely monitored with follow-up operations, provided that they do not worsen their conditions.

In the UK, 3-6 live births per 100,000 result in LMMC. There are measures that you can take to minimise this risk, one being genetic screening to become better prepared for yourself or children and the other being the intake of folic acid, either naturally or via supplements, especially if you are expecting a child.

Neural tube defects

In order to create the central nervous system (CNS) during early pregnancy, a tissue known as the neural plate folds into itself to form the neural tube. If the neural plate fails to fold properly, this can lead to neural tube defects (NTDs).¹ The severity of the NTD depends on the specific location of the defect. For example, anencephaly is caused by an improperly formed brain, and almost certainly results in death. LMMC, however, is a NTD typically located at the bottom lumbar region of the spine, so patients can survive and look toward treatment to attempt improvement for quality of life.

What is lipomyelomeningocele?

LMMC is a highly specific condition and can be considered a combination of others, as explained below:

• Meningocele: the protrusion of the meninges into an abnormal, swollen space (referred to as a herniation)
• Lipoma: an abnormal collection of fat, considered as a tumour

The meninges are three layers of membrane that surround the CNS in order to protect it. LMMC is where a lipoma fills the herniation in the lower back, breaking the meninges and leaving the CNS vulnerable to damage.²

Figure 1: Different types of spina bifida, with herniation. Grey represents the spinal cord and yellow represents lipids (fat). Aperta = open, occulta = hidden (referring to closed spina bifida).¹

NTDs that specifically affect the spine and surrounding meninges (as opposed to the brain), lead to conditions that are collectively referred to as spina bifida [Fig. 1].

As the lumbar (lower) region of the spinal cord is affected, clinical symptoms include leg weakness or paralysis as well as urinary and bowel incontinence. It is also common to have a loss of sensation within the legs and buttocks due to improper nerve connections, which can affect coordination and leave you prone to minor accidental injuries, like bruising.

Complexities of lipomyelomeningocele

LMMC is generally considered a closed spina bifida, meaning that skin covers the lipoma (abnormal fat lumps between skin and muscle) so there is little risk of infection from the environment, which is more prevalent in open spina bifida.³ Despite this, there are several complexities than can occur with LMMC.

Due to being covered by skin, MRI must be used to assess the severity of the herniation of the spinal cord. If you have ferromagnetic contents within your body, MRI could be harmful. Computer tomography (CT) scanning can be used as a substitute, but may not be as accurate in visualising the lipoma.⁴

A herniation is rarely symmetrical, and its positioning from the rest of the body varies between patients. Two complications that could develop as you grow are:

• In areas where the meninges are undamaged, neural roots (the ends of nerves) are elongated and more exposed to injury, which can worsen the lack of sensation or paralysis you may feel already, or
• The neural roots may be shorter than normal, restricting your spine’s movement and growth pattern in what is called tethered cord syndrome.

These two complications can occur simultaneously.⁴

Comorbidities (conditions that arise due to LMMC) are likely to be present, such as scoliosis, and UTIs,  emerging months after birth. As well as LMMC, these additional conditions must be addressed by doctors before any kind of treatment starts. Meninges being broken or disrupted leaves them vulnerable to infection and inflammation (commonly known as meningitis). This is a potentially life-threatening disease if left untreated.⁵

Diagnosis methods

Even if you or your child has the corresponding symptoms, it is always better to get a formal diagnosis for spina bifida; this is to assess the severity of the abnormality and create a treatment plan, which may involve surgery.⁶

Image scanning

As explained above, MRI is the most common method that doctors use to visualise LMMC, however, X-rays can be also used to visualise how the spine has formed. For foetuses, signs of spina bifida can be noticed through standard ultrasound scans and these may be more frequent, especially within the third trimester. ^[7]

Lumbar puncture

Prior to treatments, lumbar punctures are taken to extract cerebrospinal fluid using a needle in the lower back [Figure 2]. CSF can then be examined to identify spinal fluid pressure, but if you have tethered cord syndrome this could cause damage, so CT scanning is advised prior to this.

Figure 2: Illustration of lumbar puncture procedure. Patients are asked to lie on their side (left) while a needle is inserted into the spinal column (right), however they may be asked to stand depending on comfort or how much CSF can be obtained. Images taken from the NHS website.

Management options

Surgical intervention

Surgery is only considered after you have gone through a thorough assessment to determine if it would be beneficial and safe, but also effective. Having surgery does not “remove” LMMC, it merely relieves some of the tension within the spinal cord, and you will most likely require follow-up surgery afterwards alongside progress monitoring.

A reason for the necessity of follow-up is that not all the lipoma is removed to ensure the neural plate (a structure linked to the sensory nervous system) remains undamaged. Duraplasty (restoration of the dura mater, one of the meninges) is done after the fat removal, essentially closing the herniation.⁸

Folic acid

Folic acid is known to prevent the likelihood of NTDs, including spina bifida, as it is involved in repairing DNA damage in neural crest cells, which leads to the production of neurons and glial cells (that promote neuronal growth and neurotransmitter regulation).⁹

To minimise the chance of giving birth to babies with LMMC, a daily intake of folic acid is advised. If you are thinking of having a baby (and are an AFAB), you should incorporate around 400mg of folic acid daily from before conception to 12 weeks of pregnancy.

Folic acid is also beneficial to those AMAB, however this benefits sperm count and health rather than affecting the neural tube, so the chances of LMMC are not affected by this.¹⁰

Q&A

Is lipomyelomeningocele genetic?

While the characteristics of LMMC are understood, the origins of its emergence for each patient may not be known. Some people may have a genetic predisposition for LMMC, specifically if they carry defective genes called ARHGAP29 and RADIL.

If your family has a history of LMMC or any type of spina bifida but you do not have it, there is a chance that you are a carrier, whereby your future children may inherit the defective gene copy. Genetic screening is available to determine if you have any copies of mutated versions of ARHGAP29 or RADIL altogether.¹¹

Where can I get folic acid from?

If a doctor, such as an obstetrician, suggests you require higher folic acid intake (as an AFAB), you can have supplements prescribed. Over-the-counter folic acid is also available but doses are typically less.

Folic acid can also be obtained from certain foods, sources include broccoli, spinach and beans.¹⁰

Is it OK if I start taking folic acid after conception/while I am pregnant?

Folic acid does not 100% guarantee the prevention of any type of spina bifida, but influences its likelihood; incorporating it after conception is still a good idea as long as you have it regularly and at a sufficient amount (400mg).¹⁰

Summary

Lipomyelomeningocele is an impactful, complex, but overall well-understood disease. The effect on the lower spine can affect your quality of life, but there are multiple methods available for its screening and management. For both, however, choosing the right path in your treatment regimen is important to prevent complications from arising. Doctors will be able to provide the best guidance for this, especially if you are pregnant and are worried about your future child’s health, since there are simple yet effective steps you can take to minimise the risk of lipomyelomeningocele.