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Spinal cord tethering is an abnormal connection between the spinal cord and other parts of the back including the bone, muscle and connective tissues. This causes the spinal cord to stretch because the bones and other tissues of the spine grow faster than the spinal cord.
A spinal tether can take several forms, some of which are easily treated with surgery and without risk of recurrence. Other forms are quite complex and may require life-long monitoring.
The most common form of spinal cord tethering is fatty filum terminale, also called thickened filum. The filum terminale is normally a thin, flexible fiber that connects the bottom of the spinal cord to the bottom of the bones of the spine. Spinal cord tethering can occur if this fiber is thicker and stronger than normal. In such cases, the filum is typically infiltrated with abnormal fat. As the spine grows, the abnormally thick fiber stretches the spinal cord, like a rubber band.
Lipomyelomeningocele is another more complex form of spinal cord tethering, where an abnormal collection of fatty and fibrous tissue attaches broadly to the spinal cord. This tissue typically extends through the bones of the spine, through the muscle, and connects to these tissues as well as to the skin. Lipomyelomeningoceles can cause recurrent tethering and need life-long monitoring for symptoms. Surgery for lipomyelomeningocele is more complex than surgery for fatty filum terminale.
Several other malformations can cause spinal cord tethering. These include previously repaired spina bifida, splitting of the spinal cord, or cystic dilation of the bottom of the spinal cord. These conditions are much rarer than fatty filum terminale and lipomyelomeningocele.
Spinal cord tethering is a developmental abnormality, meaning that it is present before birth. It is caused by a problem with the normal spinal cord formation, such that the spinal cord does not separate from the nearby muscle, bone, fat and skin in the usual fashion.
We do not know what factors cause spinal cord tethering or any pre-natal treatments that prevent it.
Most studies suggest that girls are almost twice as likely as boys to have spinal cord tethering. Some cases of tethered spinal cord are associated with other congenital malformations in the spine, kidneys, digestive system and, less commonly, the heart. These conditions are usually obvious at birth and are a good reason to evaluate children for spinal cord tethering.
Most infants with tethered spinal cord do not have any associated birth defects. Instead, they may have marks on their skin that lead a pediatrician to look for spinal tethering. The most common marks are a dimple over the sacrum or lumbar spine, a birthmark known as a hemangioma, an abnormal collection of fatty tissue beneath the skin, or an abnormally shaped crease in their bottom.
Some children with tethered spinal cord are not identified in infancy. These children will have symptoms related to the bottom of the spinal cord. Common symptoms include back pain, leg pain, constipation, urinary dysfunction (urgency, frequency, accidents or recurrent urinary infections), foot deformities and scoliosis.
Tethering is sporadic and typically does not run in families.
Many cases of spinal cord tethering are identified in infancy because of the specific marks the condition causes on the skin of a baby’s back. In these cases, surgery can usually prevent development of symptoms.
When symptoms develop, the most common ones include back pain, leg pain, constipation, urinary dysfunction (urgency, frequency, accidents, recurrent urinary infections), foot deformities and scoliosis, a curving of the spine.
Once symptoms have already developed, surgery will typically stop back and leg pain. Other symptoms - particularly urinary problems - will usually stop getting worse after surgery, but they typically do not improve. Surgery will prevent any further damage, but it will not reverse the damage already done.
An MRI of the low back is the most definitive test for spinal cord tethering, and often the only test needed. This test uses magnetic fields to give a very clear picture of the anatomy of the spine.
An ultrasound of the low back can be performed in infants 4 months old and younger. The advantage of ultrasound is that sedation is not needed; the disadvantage is that ultrasound can miss cases of spinal cord tethering.
For older children with bladder symptoms, an evaluation by a urologist is recommended. This may include testing of how the bladder muscle and associated muscles are working.
An MRI is not a painful procedure, but it does require the patient to hold still while inside of the machine for about 45 minutes – which is why most children and all infants require sedation during the scan.
Children’s Colorado has the most experience in the state of Colorado and the surrounding seven-state region with evaluations for tethered spinal cord. Our radiology department frequently performs MRIs for this condition, and all of the children who need sedation are cared for by anesthesiologist specifically trained in and exclusively practicing pediatric anesthesia.
How do doctors at Children’s Colorado diagnose spinal cord tethering?
Our evaluation begins with discussing your child’s medical history and then doing a physical examination to determine whether a further test is needed. In most cases, only an MRI is required to diagnose spinal cord tethering.
Most cases of spinal cord tethering are treated with surgery. The surgery may be relatively straightforward with minimal risk, or may be more involved depending on your child’s type of spinal tether.
Some cases of very minor tethering in a child without symptoms can be monitored without surgery. This is a decision that our practitioners counsel parents about regularly.
Children’s Colorado has the only neurosurgeons in the state dedicated exclusively to pediatric neurosurgery. We have the largest practice and the greatest experience in tethered spinal cord surgery in the surrounding seven-state region.
Surgeons at Children’s Colorado also use the latest technology to achieve the best outcomes. This includes technologies like the surgical microscope, operative laser and neurological monitoring.
Neuromuscular Medicine, Neurology
Certified Pediatric Nurse Practitioner