Tethered Spinal Cord

Tethered spinal cord is a neurological condition where the spinal cord is abnormally attached (tethered) to the tissues surrounding the spine. This attachment restricts the spinal cord's movement, causing it to stretch as the body grows or moves. This stretching can damage the spinal cord and nerves, leading to various symptoms, especially in children.

What is Tethered Spinal Cord?

Tethered spinal cord is a condition where the bottom of the spinal cord is stuck to the surrounding tissues inside the spinal canal. Normally, the spinal cord floats freely within the spinal column. When it's tethered, movement and growth can cause the spinal cord to stretch, potentially leading to nerve damage and a range of symptoms.

The spinal cord is a long, delicate bundle of nerves that extends from the brain down the back. It carries messages between the brain and the rest of the body. In a healthy spine, the spinal cord ends around the first or second lumbar vertebra (lower back bones) and moves freely within the spinal canal. With a tethered spinal cord, this lowest part of the spinal cord is held in place by a band of fibrous tissue, a fatty tumor, or other abnormalities. This prevents the spinal cord from moving up and down as it should. As a person grows or bends, the spinal cord can become stretched, which can interfere with its blood supply and nerve function. This stretching and reduced blood flow can lead to progressive damage to the nerves within the spinal cord. The condition can be present at birth (congenital) or develop later in life due to injury or surgery. Symptoms often worsen over time without treatment.

Symptoms

Symptoms of a tethered spinal cord can vary widely, often affecting the legs, bladder, and bowel. In children, signs might include skin changes on the lower back, foot deformities, or problems with walking. Adults may experience back pain, leg weakness, or bladder control issues that develop over time.

Symptoms can appear at any age, but they are often noticed during childhood. In infants, a tethered spinal cord might be suspected if there are certain skin marks on the lower back, such as a dimple, a patch of hair, a fatty lump (lipoma), or a discoloration. Foot deformities, such as clubfoot or high arches, or differences in leg size can also be early signs. As children grow, they might develop problems with walking, such as tripping or dragging a foot. They may also experience weakness, numbness, or pain in their legs or feet. Bladder and bowel control issues, like frequent urinary tract infections, bedwetting (even after being potty-trained), or constipation, are common because the nerves controlling these functions are affected. In adults, symptoms often include chronic lower back pain that worsens with activity, leg weakness, numbness, or tingling. Bladder and bowel dysfunction, such as incontinence or difficulty emptying the bladder, are also frequent complaints. Symptoms in adults can sometimes appear or worsen after an injury or pregnancy.

Causes & risk factors

Tethered spinal cord is usually caused by conditions present at birth that affect the development of the spinal cord and surrounding structures. These include certain types of spina bifida or other malformations. Less commonly, it can develop later in life due to scar tissue from injury, surgery, or tumors.

Most cases of tethered spinal cord are linked to birth defects that occur when the spine and spinal cord are forming during pregnancy. One common cause is a type of spina bifida called spina bifida occulta, where there is a small gap in the bones of the spine, but the spinal cord itself is usually covered by skin. Other conditions, like a fatty tumor (lipoma) within the spinal canal or a thickened filum terminale (the thin thread-like tissue at the end of the spinal cord), can also cause tethering. Sometimes, the spinal cord can become tethered later in life. This can happen due to scar tissue forming after spinal surgery, such as for a herniated disc, or after a spinal injury. Tumors or cysts in the spinal canal can also cause the spinal cord to become stuck. These acquired forms are less common than those present from birth. While the exact reasons for these developmental abnormalities are not always clear, they are not typically inherited. There are no specific lifestyle risk factors known to cause tethered spinal cord. The primary risk factor is the presence of these underlying congenital spinal conditions or a history of spinal trauma or surgery.

How it's diagnosed

Diagnosing a tethered spinal cord typically involves a physical exam, a review of symptoms, and specialized imaging tests. Magnetic resonance imaging (MRI) is the most common and effective tool, providing detailed pictures of the spinal cord and surrounding tissues to identify the tethering.

A doctor will usually begin by taking a detailed medical history and performing a physical examination. They will look for external signs on the lower back, assess muscle strength, reflexes, and sensation in the legs, and check for any foot deformities. They will also ask about bladder and bowel function. The most important diagnostic tool is magnetic resonance imaging (MRI) of the spine. An MRI uses powerful magnets and radio waves to create detailed images of the spinal cord, nerves, and surrounding tissues. It can clearly show if the spinal cord is positioned too low or if there are any structures, like a fatty tumor or scar tissue, that are holding it in place. Other tests might be used in specific situations. For example, a computed tomography (CT) scan may be used if an MRI is not possible, though it provides less detail of the soft tissues. Urodynamic studies, which measure how well the bladder and urethra store and release urine, may be performed if bladder control issues are a significant symptom, helping to assess nerve function to the bladder.

Treatment options

The primary treatment for a tethered spinal cord is surgery to release the tethering, which aims to prevent further nerve damage and relieve symptoms. The decision to operate depends on the severity of symptoms and the risk of progression. Surgery is often recommended, especially in children, to untether the spinal cord.

The main goal of treatment is to free (untether) the spinal cord, allowing it to move normally again. This is typically achieved through a surgical procedure called detethering surgery. The surgery involves carefully opening the spinal canal and cutting the fibrous band or removing the fatty tissue that is holding the spinal cord in place. For children, surgery is often recommended early, even if symptoms are mild, to prevent progressive nerve damage as they grow. Early intervention can help improve or stabilize neurological function, especially regarding leg weakness and bladder control. The timing of surgery in adults depends on the severity and progression of symptoms, as well as the potential risks. While surgery can often relieve symptoms and prevent further damage, it cannot always reverse existing nerve damage. Some symptoms, particularly those related to bladder and bowel function, may not fully improve after surgery. Physical therapy may be recommended after surgery to help with recovery and improve strength and mobility. Regular follow-up appointments are important to monitor for any recurrence of tethering, which can happen in some cases, especially in children with complex spinal conditions.

Recovery & outlook

Recovery after tethered spinal cord surgery varies, with many people experiencing improvement or stabilization of symptoms. The outlook is generally better with early diagnosis and treatment before significant nerve damage occurs. Regular follow-up is crucial, as tethering can sometimes recur, particularly in growing children.

After surgery, recovery involves a period of rest and gradual return to activity. Many people experience relief from pain and improvement in neurological symptoms, such as leg weakness or numbness. However, the extent of improvement depends on how much nerve damage occurred before surgery and how long symptoms were present. For children, early surgery often leads to better outcomes, helping to prevent the worsening of symptoms as they grow. Some children may see improvements in bladder and bowel function, while others may require ongoing management for these issues. Physical therapy can play a vital role in regaining strength, flexibility, and improving walking ability. It is important to understand that while surgery can untether the spinal cord, it doesn't always reverse all existing damage. Some symptoms, especially long-standing bladder or bowel problems, may persist even after successful surgery. In some cases, particularly in children with complex spinal conditions, the spinal cord can become tethered again (retethering), requiring further monitoring and potentially additional surgery. Lifelong follow-up with a medical team is often recommended to monitor for any new symptoms or signs of retethering.

When to see a doctor

You should see a doctor if you or your child develop symptoms that suggest a tethered spinal cord, especially new or worsening back pain, leg weakness, numbness, or changes in bladder or bowel control. In infants, specific skin markings on the lower back, like dimples or hair patches, warrant medical evaluation.

If you notice any of the potential signs of a tethered spinal cord, it is important to consult a doctor. For infants and young children, this includes unusual skin markings on the lower back, such as a deep dimple, a tuft of hair, a fatty lump, or discolored skin. Also, seek medical advice if your child has foot deformities, differences in leg size, or problems with walking, such as tripping or dragging a foot. For older children and adults, concerning symptoms include new or worsening lower back pain, especially if it radiates down the legs. Weakness, numbness, or tingling in the legs or feet that is getting worse should also prompt a doctor's visit. Any new difficulties with bladder or bowel control, such as incontinence, frequent urinary tract infections, or constipation, are also important to discuss with a healthcare provider. Early diagnosis and treatment can help prevent further nerve damage and improve outcomes. Do not delay seeking medical attention if you suspect a tethered spinal cord, as timely intervention can make a significant difference in managing the condition and its symptoms.

Frequently asked questions

Can a tethered spinal cord heal on its own?

No, a tethered spinal cord does not heal on its own. The abnormal attachment of the spinal cord to surrounding tissues is a physical issue that requires medical intervention. Without treatment, the condition can worsen over time, leading to progressive nerve damage and more severe symptoms.

Is tethered spinal cord a genetic condition?

While some conditions associated with tethered spinal cord, like spina bifida, can have a genetic component, tethered spinal cord itself is not typically considered a directly inherited genetic condition. Most cases are due to developmental abnormalities that occur during pregnancy, rather than being passed down through families.

What are the long-term effects of an untreated tethered spinal cord?

Without treatment, an untreated tethered spinal cord can lead to progressive and irreversible nerve damage. This can result in worsening leg weakness, numbness, chronic pain, severe bladder and bowel dysfunction (like incontinence), and increasing difficulty with walking and mobility over time.

How common is tethered spinal cord?

The exact prevalence of tethered spinal cord is not precisely known, as many mild cases may go undiagnosed. However, it is considered a relatively rare condition. It is more commonly associated with other congenital spinal abnormalities like spina bifida occulta, which affects about 1 in 1,000 to 1 in 2,000 newborns.

Can adults develop a tethered spinal cord?

Yes, while often present from birth, adults can develop a tethered spinal cord. This can happen due to scar tissue forming after spinal surgery or injury, or from tumors or cysts in the spinal canal. Symptoms in adults may appear gradually or worsen after a specific event like an injury or pregnancy.

What is the success rate of tethered spinal cord surgery?

Tethered spinal cord surgery is generally successful in preventing further neurological deterioration and often improves existing symptoms, especially pain and leg weakness. However, the success rate for complete symptom resolution, particularly for bladder and bowel issues, can vary. Early surgery typically leads to better outcomes, but some symptoms may persist, and retethering can occur in a minority of cases.

Sources

• MedlinePlus — Tethered Spinal Cord
• Mayo Clinic — Tethered Spinal Cord
• Cochrane Library — Tethered Spinal Cord