Spinal Lipoma

What a spinal lipoma is

During early pregnancy, the neural tube that forms the spinal cord closes, and the skin and fat separate from it. If fat tissue becomes trapped in or attached to the developing cord, it forms a lipoma. Because skin covers the defect, it is called a closed spinal dysraphism, unlike the open form of spina bifida (myelomeningocele).

Types

• lipomyelomeningocele: the fat connects through a gap in the spine to the spinal cord, often with the cord bulging outward
• lipomyeloschisis: fat joins the cord directly where it failed to close
• filum terminale lipoma ("fatty filum"): fat in the thin band (filum) that anchors the bottom of the cord. Often mild and found by chance on MRI
• intradural lipoma: fat within the spinal canal, sometimes higher in the spine, rarely presenting in adults

Spinal epidural lipomatosis, an excess of normal fat around the spinal cord in adults, is a different condition linked to steroid use and obesity.

Signs at birth

Many spinal lipomas are suspected because of a skin marker over the lower back:

• a soft, fatty lump above the buttocks
• a dimple, especially if deep, large or above the crease of the buttocks
• a tuft of hair
• a red or purple birthmark (hemangioma)
• a skin tag or tail-like appendage
• an asymmetric buttock crease

Babies may have normal leg movement and bladder function at first.

Tethered cord and symptoms

Normally, the bottom of the spinal cord moves freely within the spinal canal as a child grows. A lipoma can anchor the cord, so it is stretched with growth and movement. This tethered cord syndrome can cause:

• leg and foot problems: weakness, numbness, one leg or foot smaller than the other, high arches, clubfoot or claw toes, walking changes
• pain: in the back or legs, often worse with bending or activity
• bladder problems: leaking, frequent infections, difficulty emptying, delayed toilet training (neurogenic bladder)
• bowel problems: constipation or leaking
• scoliosis (curvature of the spine)
• skin sores on numb feet

Symptoms often appear during growth spurts. Some people are first diagnosed as teens or adults.

Diagnosis

• ultrasound of the spine in babies under about 3 to 6 months, before the bones harden
• MRI of the spine: the main test, showing the lipoma and position of the spinal cord
• urodynamic studies to check bladder function
• neurological and orthopedic examination of the legs and feet
• baseline and regular assessments to detect changes early

Treatment

Monitoring

Some children, particularly those with a fatty filum and no symptoms, are monitored with regular neurological checks, bladder tests and imaging.

Surgery

Surgery aims to remove as much fat as safely possible and release (untether) the spinal cord. Approaches vary:

• many neurosurgeons recommend surgery when symptoms develop or worsen
• some recommend early or "prophylactic" surgery for certain types in infancy, to prevent future damage
• a simple fatty filum can be cut in a relatively small operation

Surgery aims to prevent further damage. It may not reverse problems already present, which is why monitoring matters. Nerve monitoring during surgery helps protect function. The cord can re-tether later, needing further surgery.

Ongoing care

• urology: clean intermittent catheterization or medicines for bladder problems
• bowel programs
• orthopedics and physical therapy for foot and leg problems, braces or surgery
• skin care for areas with reduced sensation

Outlook

Outlook varies by type and how early problems are recognized. Many children with spinal lipomas lead active lives. Some have lasting bladder, bowel or leg problems, especially if nerve damage occurred before treatment. Lifelong follow-up helps detect re-tethering.

Frequently asked questions

What is a spinal lipoma?

It is a fatty mass attached to the spinal cord or its coverings, usually in the lower back and present from birth. It is a form of closed spina bifida and can tether the spinal cord, causing nerve problems as a child grows.

What are the signs of a spinal lipoma in a baby?

Look for a soft lump above the buttocks, a deep dimple, a hair tuft, a birthmark or a skin tag over the lower spine. Babies with these signs should have a spinal ultrasound or MRI.

Does a spinal lipoma need surgery?

Not always. Children without symptoms may be monitored. Surgery is usually recommended when symptoms such as leg weakness, pain or bladder problems develop, and sometimes early in infancy for certain types. The decision is made with a pediatric neurosurgeon.

Can a spinal lipoma cause problems in adults?

Yes. Some people are diagnosed as adults when tethered cord symptoms appear, such as back and leg pain, numbness, weakness or bladder changes, often after activity or injury. Surgery can help relieve symptoms.