When the spinal cord is anchored lower than it should be
If your child has been told that they may have a tethered spinal cord (sometimes called tethered cord syndrome), this page explains what that means in plain language, why it can cause problems as a child grows, and what the surgery is for. The information here is general, your child's neurosurgeon will discuss what applies specifically to your child.
The spinal cord runs from the brain down through the spinal canal, ending in a thin thread of tissue called the filum terminale, which attaches to the bottom of the spine. Normally, the cord can glide slightly inside the canal as the child moves and grows. As the child gets taller, the spine grows faster than the cord, and the lower end of the cord settles into its usual position.
In a tethered spinal cord, the lower end of the cord is anchored (stuck) to something at the bottom of the spinal canal and cannot move freely. As the child grows, the cord is gently stretched. Over time, that stretching can interfere with how the nerves at the bottom of the cord work, the nerves that control the legs, the bladder, the bowel, and the sensation in the lower body.
There are several different reasons that a cord can be tethered, and your child's team may use one of the following names:
A tight or thickened filum terminale is the simplest cause, the connecting thread itself is too short, too thick, or contains fatty tissue.
A spinal lipoma is a fatty mass attached to the lower end of the cord that holds it in place. When the lipoma extends out through the skin or there is an opening in the bones above it, it may be called a lipomyelomeningocele.
A dermal sinus tract is a small tract connecting the skin on the lower back to the spinal canal, it can tether the cord, and it can also let infection in.
A split cord malformation (diastematomyelia) is where the cord is divided into two halves by a piece of bone or fibrous tissue, which can tether one or both halves.
Re-tethering after spina bifida surgery is when scar tissue from an earlier myelomeningocele repair holds the cord down as the child grows. See the spina bifida page for more on this.
An important point, some children have one of these anatomical findings on a scan but never develop symptoms. Tethered cord becomes a "syndrome" only when the stretching of the cord actually starts to cause problems. Whether (and when) to operate is a careful decision your team will make with you.
Tethered cord is often suspected because of a particular pattern of findings, something visible on the lower back, something the legs or the feet are doing, or something to do with the bladder, the bowel, or the back. The skin signs often appear first, and one specific point matters, not every dimple on a baby's lower back is a sign of tethering. See the note in the diagnosis section.
The first step is a careful examination of the lower back and the legs by a doctor who knows what to look for. Some children are referred because their paediatrician sees a skin finding at a well-baby check. Others are referred because of new bladder, foot, or back symptoms. A neurological examination of the legs and a check of the bladder and bowel pattern are part of every assessment.
About sacral dimples, a small, simple dimple right in the middle of the very bottom of the back (at the top of the buttock cleft) is very common and almost always harmless. It does not need any test. A dimple becomes worth investigating when it is large or deep, when it is high above the buttock cleft, when it is off-centre, when there is hair or a tuft growing from it, when there is a tract that seems to go inward, or when there is another skin finding nearby (a lump, a birthmark, a port-wine stain). Your child's doctor will know which is which.
In babies whose lower spine bones have not yet ossified (usually under about 3 months of age), an ultrasound of the lower back can give a good first look at the spinal cord. The scan is painless, uses no radiation, and is often the first test for a worrying skin finding.
In older babies and children, the test of choice is an MRI of the spine. The MRI shows the position of the cord, the appearance of the filum, any lipoma or other tethering element, and any associated findings. Your child may need light sedation to lie still for the scan.
If there are bladder or bowel symptoms, your child will also be reviewed by a paediatric urologist. A test called urodynamics measures how the bladder fills and empties, and it is sometimes the most sensitive way of detecting a subtle problem from a tethered cord, sometimes even before the MRI shows clear changes.
The treatment for a tethered cord that is causing (or is likely to cause) problems is surgery to release the cord. Not every tethering finding needs surgery, and the decision is taken carefully by the neurosurgeon based on the specific anatomy, the child's symptoms, and the age. There are no medications that release the cord, surgery is the only treatment that addresses the cause.
The main goal of untethering surgery is to stop the cord from being damaged any further. Symptoms that are already present sometimes improve after the operation, back pain often improves, bladder symptoms can improve or stabilise, established weakness or foot deformities usually do not reverse but stop getting worse. Your team will give you a realistic picture of what to expect for your child.
Untethering operations are usually well tolerated. After the operation, your child will typically need to lie flat in bed for one or two days to help the wound heal and to reduce the risk of a cerebrospinal fluid (CSF) leak. The hospital stay is usually two to five days, depending on which operation was performed and how things are going.
Once home, most children take it easy for about two to four weeks before returning to school. Heavy activity, sport, and swimming usually wait six weeks or so, until the neurosurgeon confirms that the wound has healed. The team will give you written instructions specific to your child.
If your child had bladder symptoms before the operation, follow-up urodynamic testing (usually a few months after the surgery) helps to see whether the bladder is improving. Some children's bladders improve dramatically, for others ongoing urological care remains important. The urologist on your child's team will guide this.
In the longer term, your child will be followed by the neurosurgery team to watch for re-tethering, which can occur, particularly in lipoma cases and after spina bifida surgery. New back pain, new weakness, new bladder changes, or a new curve in the spine are the signs to mention at follow-up. Most children, however, do well after their first untethering and do not need a second operation.
Most children with a tethered cord, whether operated on or carefully watched, grow up to live full and active lives. The key is recognising the condition early and following up regularly, so that small changes can be acted on before they cause lasting problems.
After untethering surgery, certain signs can mean a complication, a CSF leak, an infection, or a problem with healing. And in any child being watched for a tethered cord, new symptoms can mean that the cord is being affected and that the situation needs to be reassessed quickly. Do not wait, contact the neurosurgery team (or go straight to the emergency department) right away if you notice any of the following:
If your child is difficult to rouse, is having a seizure, or has had a sudden change in the legs or the bladder, this is an emergency, go to the nearest emergency department or call the emergency services immediately.