Tethered Cord Syndrome

What tethered cord syndrome is

In early development, the spinal cord runs the whole length of the spinal canal. As the spine grows faster than the cord, the lower end of the cord (the conus medullaris) normally rises to around the level of the first or second lumbar vertebra by infancy. It is anchored only loosely by a thin, elastic strand called the filum terminale, so the cord can glide as you bend.

In tethered cord syndrome, the cord is pinned down. It is pulled tight during growth spurts and with bending, which reduces blood flow and damages nerve cells in the lower cord. The result is a slowly progressive loss of function in the legs, bladder and bowel.

Causes

Primary (congenital) tethered cord

Linked to birth defects of the spine, called spinal dysraphism:

• Myelomeningocele: the open form of spina bifida. Nearly all children who have had it repaired have a tethered cord on MRI, though not all develop symptoms.
• Spinal lipoma (lipomyelomeningocele): fatty tissue fused to the cord.
• Tight or fatty filum terminale.
• Dermal sinus tract: a channel from the skin to the spinal canal, which can also cause meningitis.
• Split cord malformation (diastematomyelia).

Secondary tethered cord

Scar tissue after earlier spinal surgery (including spina bifida repair), spinal injury, infection or tumors can stick the cord down again. This is called retethering.

Symptoms

In babies and young children

• Skin markers over the lower spine: a tuft of hair, deep or off-center dimple, fatty lump, red or purple birthmark, or skin tag
• Differences in leg length, muscle size or foot shape
• Delayed walking or toilet training
• Repeated urinary tract infections

In older children and teens

• Back pain, and leg pain or numbness, worse with activity or bending
• Leg weakness, clumsiness or changes in walking
• Foot deformities such as high arches and clawed toes, often progressive
• Scoliosis that worsens quickly
• Urinary incontinence, urgency, frequency or recurrent infections; constipation or soiling

In adults

Tethered cord can first cause symptoms in adulthood, often triggered by activities that flex the spine, a fall, or pregnancy:

• Severe low back pain spreading into the legs or genital area, often not following a single nerve pattern
• Numbness, weakness or muscle wasting in the legs
• Bladder problems such as urgency, frequency or incomplete emptying (neurogenic bladder)
• Bowel and sexual dysfunction

Diagnosis

1. Neurological examination: strength, sensation, reflexes, gait and foot shape, plus a look at the skin over the spine.
2. MRI of the spine: shows a low-lying conus (below L2), a thickened or fatty filum, lipomas, syrinxes (fluid cavities in the cord, see syringomyelia), and other malformations.
3. Spinal ultrasound: in babies under about 3 to 4 months, before the bones harden, as a screening test.
4. Urodynamic studies: measure bladder pressure and emptying, an important baseline and a sensitive sign of change.
5. X-rays for scoliosis and bony abnormalities.

A low-lying cord on MRI alone does not always need surgery. Doctors look for symptoms or worsening function.

Treatment

Untethering surgery

A neurosurgeon makes an incision over the lower spine, opens the dura (the covering of the spinal cord) and releases the cord, for example by cutting the filum terminale or freeing scar tissue or a lipoma. Nerve monitoring during the operation helps protect function. Most patients stay in the hospital for a few days and lie flat for a short time to reduce spinal fluid leak.

• Pain usually improves well after surgery.
• Weakness, sensory changes and bladder problems often stabilize and may improve, though long-standing damage may not reverse.
• Some children, especially those with spina bifida or lipomas, retether and need repeat surgery.

Ongoing management

• Bladder management: timed voiding, medicines, or clean intermittent catheterization
• Bowel programs for constipation and continence
• Physical therapy, orthotics and orthopedic surgery for foot deformities
• Monitoring and treatment of scoliosis
• Regular follow-up with neurosurgery, urology and orthopedics, especially during growth spurts

Outlook

Early diagnosis and surgery before major nerve damage give the best results. Prophylactic surgery in children without symptoms is debated and decided case by case. People with a tethered cord from spina bifida need lifelong follow-up because symptoms can recur. Adults with newly diagnosed tethered cord often have meaningful pain relief after untethering.

Frequently asked questions

What are the symptoms of tethered cord syndrome?

The main symptoms are low back pain, leg pain or numbness, leg weakness or changes in walking, foot deformities, worsening scoliosis, and bladder or bowel problems such as leaking, urgency and frequent infections. In babies, the first sign is often a skin marker over the lower back.

Can adults have tethered cord syndrome?

Yes. Some people born with a mild tethered cord have no symptoms until adulthood, when bending activities, injury, pregnancy or degeneration stretch the cord. Adults typically have severe back and leg pain, numbness and bladder problems. MRI diagnoses it, and surgery often relieves pain.

Is tethered cord surgery serious?

It is major spinal surgery but is commonly performed and generally safe in experienced hands. Risks include spinal fluid leak, infection, and rarely new weakness or bladder problems. Nerve monitoring during the operation reduces risk. Most people go home within a few days.

Can a tethered cord come back after surgery?

Yes. Scar tissue can reattach the cord, which is called retethering. It is more common after spina bifida and lipoma repairs and during growth spurts. Regular follow-up watches for returning pain, weakness, foot changes or bladder problems, which may need another operation.

What does a sacral dimple have to do with tethered cord?

Most small dimples within the buttock crease are harmless. A dimple that is deep, larger than about 5 mm, more than 2.5 cm above the anus, or combined with hair, a birthmark, a fatty lump or a skin tag can signal hidden spinal dysraphism. A spinal ultrasound or MRI is then recommended.