Tethered Cord is a condition where the bottom end of the spinal cord is fixed, so that it can’t move freely inside the spinal bones as it should.
Before birth, the spinal cord is long, compared with the size of the baby, and ends at the bottom of the spinal canal.
As a typically developing child grows, the spinal cord doesn’t grow, so the bottom end ‘rides up’ inside the bones; by the time the child reaches their adult height, the cord should end at around the first lumbar vertebra (L1).
This ‘riding up’ is prevented in Tethered Cord. The spinal cord can be tethered by lipomas (fatty lumps) in the spinal canal, scar tissue from previous surgery (such as back closure for open spina bifida), or being attached to the skin by deep dimples or sinuses. The spinal cord therefore becomes stretched, and symptoms may begin during times of rapid growth, at around 2 years, 7-8 years, and with puberty.
Sometimes, symptoms appear in middle age, as deterioration of the spinal cord begins after many years of tethering.
Diagnosis is made by neurological examination, to check how the nerves and spinal cord are functioning, and by MRI, to check where the cord ends, and to identify anything which might be tethering it, such as lipoma. If bladder and bowel involvement is suspected, these should be investigated separately, by a urologist.
Tethering in children may require surgery to release the cord and/or remove the tissue causing the tethering. The surgery aims to prevent further deterioration and relieve pain, and timing is important for maximum benefit.
While improvements in function may be seen, they cannot be guaranteed and further de-tethering surgery may be needed if the cord later re-tethers, for example owing to scar tissue from previous surgery.
Increasingly, adults in their middle years with spina bifida tell us that they are experiencing symptoms of tethered cord.
Although the cord has been tethered since growth ended in their late teens, the symptoms begin after many years owing to ‘wear and tear’ on the cord in the lumbar area, from twisting, bending etc.
Surgery to release the spinal cord may be possible to prevent further deterioration; however the cord may have been quite damaged from years of tethering.
As the spinal cord and brain are connected, de-tethering surgery is sometimes carried out to relieve symptoms of Chiari II which is a feature of Myelomeningocoele in which the tonsils of the cerebellum protrude into the spinal canal.