Tethered Spinal Cord Syndrome

Overview

Tethered spinal cord syndrome is a neurologic disorder caused by tissue attachments that limit the movement of the spinal cord within the spinal column. These attachments cause an abnormal stretching of the spinal cord. This syndrome is closely associated with spina bifida. It is estimated that 20-50% of children with spina bifida defects that are repaired shortly after birth will require surgery at some point to untether the spinal cord.

Myelomeningocele/Lipomyelomeningocele

The lower tip of the spinal cord is normally located opposite the disc between the first and second lumbar vertebrae in the upper part of the lower back. In people with spina bifida (myelomeningocele), the spinal cord fails to separate from the skin of the back during development, preventing the spinal cord from ascending normally; therefore, the spinal cord is low-lying, or tethered. In patients with a lipomyelomeningocele, the spinal cord will have fat at the lower tip, and this fat may connect to the fat that overlies the thecal sac (a fluid filled sac that the spinal cord “floats” within) that may also lead to thethering.

Although the skin is separated and closed at birth, the spinal cord stays in the same location after the closure. As a child continues to grow, the spinal cord can become stretched, causing damage and interfering with the blood supply to the spinal cord.

SYMPTOMS + TYPES

In addition to myelomeningocele and lipomyelomeningocele discussed above, the following are other causes of tethered cord that vary in severity of symptoms and treatment:

• Dermal sinus tract (a rare congenital deformity)
• Diastematomyelia (split spinal cord)
• Lipoma (a benign, fatty growth)
• Tumor
• Thickened/tight filum terminale (a delicate filament near the tailbone)
• A history of spine trauma
• A history of spine surgery

Symptoms in Children

The symptoms listed below are some of the ways in which tethered spinal cord syndrome may be exhibited in children:

• Lesion on the lower back
• Fatty tumor or deep dimple on the lower back
• Skin discoloration on the lower back
• Hairy patch on the lower back
• Back pain, worsened by activity and relieved with rest
• Leg pain, especially in the back of legs
• Leg numbness or tingling
• Changes in leg strength
• Deterioration in gait
• Progressive or repeated muscle contractions
• Leg deformities
• Spine tenderness
• Scoliosis (curvature of the spine)
• Bowel and bladder problems

Although it is rare, a patient with tethered spinal cord can continue undiagnosed into adulthood. In such cases, the strain on the spinal cord increases, leading to increasing sensory and motor problems, as well as loss of bladder and bowel control.

TESTING + DIAGNOSIS

If a tethered cord is suspected, one or more tests may be necessary to confirm the diagnosis.

• MRI: A diagnostic test that, using powerful magnets and computer technology, produces three-dimensional images of body structures; can show the spinal cord, nerve roots, and surrounding areas, as well as enlargement, degeneration, and displacement
• Myleogram: An x-ray of the spinal canal following injection of a contrast material into the thecal sac; can show pressure on the spinal cord or nerves caused by tethered spinal cord
• CT or CAT scan: A diagnostic image created after a computer reads x-rays; may be used after a myelogram to show how the dye flows around the spinal cord and nerves
• Ultrasound: A water-soluble gel is placed on the skin where the transducer (a handheld device that directs the high-frequency sound waves to the spine) is to be placed. The gel helps to transmit the sound to the skin surface. The ultrasound is turned on, and images of the spinal cord moving in the thecal sac are obtained

TREATMENT + CARE

Surgery

Untethering is generally performed only if clinical signs or symptoms of deterioration are observed. The surgery involves opening the scar from the prior closure down to the covering (dura) over the myelomeningocele. Sometimes a small portion of the bony vertebrae (laminae) are removed to obtain better exposure or to decompress the spinal cord. The dura is then opened, and the spinal cord and myelomeningocele are gently dissected away from the scarred attachments to the surrounding dura. Once the myelomeningocele is freed from all scarred attachments, the dura and the wound are closed.

The child usually can resume normal activities within a few weeks. Recovery of lost muscle and bladder function depends upon the degree and length of preoperative implications. The combined complication rate of this surgery is usually 1-2%. Complications include infection, bleeding, and damage to the spinal cord or myelomeningocele, which may result in decreased muscle strength or bladder or bowel function. Many children require only one untethering procedure. However, because symptoms of tethering can occur during periods of growth, 10-20% of children with this syndrome require repeated surgery.

Follow-Up

Treatment of a tethered cord syndrome does require follow-up with the treating neurosurgeon and typically with physical therapy/ occupational therapy. After some time, follow-up with the neurosurgeon may be on an as needed basis or if symptoms return.