Spinal cord lipomas and lipomyelomeningoceles

Introduction

Spinal cord lipomas are a collection of fat cells that have formed into a lump or mass in the lower part of the spinal canal, in or near the spinal cord. A spinal lipoma often presents without any skin or bone abnormalities. That is, it may not be noticeable. The abnormal cells may engulf nerve roots and extend deep within the cord. This is often diagnosed later in life as an unexpected finding on a scan, or once symptoms develop.

Spinal cord lipomas develop during the early weeks of pregnancy and are associated with spina bifida (a type of neural tube defect, where the spine and spinal cord don't form properly).

Lipomas grow as the child grows and they can cause tethering of the spinal cord. When this causes tension on the spinal cord and leads to loss of function, your child  may need surgery.

A lipomyelomeningocele (pronounced lipo-my-elo-men-IN-go-seal) is a large collection of fat cells located in the spinal canal which comes out through a gap or opening in the vertebrae.  It is visible under the skin on the child’s back from birth, and looks like a large soft tissue swelling or lump in the lower back or in the buttocks, usually uneven. It is also associated with spina bifida. Similar to the common type of spina bifida (myelomeningocele) it also develops in the first weeks of pregnancy.

Babies with a lipomyelomeningocele have a spinal cord that is stuck (tethered) into the fatty mass on their back. This may pull the spinal cord downward, which can cause neurological changes or functional loss.

Lipomyelomeningoceles are usually seen at birth or become noticeable within the first few months to the first years of life. The soft tissue swelling over the spine in the lower back is covered by skin and is not usually painful.

Your child might have:

• lower limb weakness
• development of spasticity (muscle spasms and stiffness)
• foot deformity leading to problems with walking, trips or falls
• changes in bladder and bowel control or function
• gradual curving of the back (scoliosis).

Symptoms of lipomyelomeningoceles are usually due to tethering of the spinal cord, especially during growth spurts (due to tension).

Lipomyelomeningoceles are sometimes seen on screening ultrasound scans when the baby is developing in the uterus.  Prenatal diagnosis can be useful in planning appropriate neonatal care of your baby.

If the lipomyelomeningocele is not identified before birth, ultrasound scanning of the spine and lump is usually done first. When a lipomyelomeningocele is suspected, magnetic resonance imaging (MRI scan) is used to confirm the diagnosis. An MRI will help the surgeon plan the operation. Plain X-rays will show the gap or opening in the vertebrae in most cases. Sometimes other tests (such as urodynamic testing by the urologist to check for changes in the bladder function) may be needed.

Surgery is often needed to prevent further decline of function related to the tethering of the spinal cord. To achieve this, the surgeon will need to ‘untether’ the abnormal attachment of the spinal cord to the other structures. The surgeon may also try to reduce the bulk of the fatty cells under the skin for cosmetic reasons (de-bulking). This has extra risks involved, such as fatty cells might die (necrosis). This can lead to problems deeper down with infection, leakage of fluids and additional scar tissue being formed. This in itself can cause re-tethering or loss of function.

As a  child with a lipomyelomeningocele grows, the cord can again come under tension and the surgery might have to be repeated when symptoms recur.

Usually the initial surgery will be done some time in the first year of life when the child can have a general anaesthetic safely. This will prevent neurological or functional changes in later life. When symptoms recur, the surgery will be done at the time of the diagnosis to prevent further decline and hopefully to have some recovery from functional loss.

The Spina Bifida Association (in the United States) has several fact sheets about lipomyelomeningoceles and tethered cord syndrome