Klippel-Feil Syndrome (KFS)

Klippel-Feil syndrome (KFS) is a condition in which you have two or more neck bones (vertebrae) fused together. KFS causes spine abnormalities and can affect many other body areas. Symptoms include short neck, limited neck mobility and low back-of-head hairline. Treatment depends on severity of your symptoms. Treatments range from devices to protect your spine to surgery.


A woman with Klippel-Feil syndrome.
In Klippel-Feil syndrome, vertebrae in your cervical spine are fused.

What is Klippel-Feil syndrome (KFS)?

Klippel-Feil syndrome (KFS) is a rare condition in which two or more of the bones in your neck are fused (abnormally joined) together. These bones are called cervical spine vertebrae. This can also affect other vertebrae in your spine beyond the neck region.

This may involve many other parts of your body, including your heart and lungs, kidneys, mouth, eyes and ears, muscles and nerves, spinal cord and other bones.

Your spine consists of 33 vertebrae. The first seven vertebrae are called your cervical vertebrae, with C1 being closest to the base of your skull, and C7 being the last vertebra in this section. KFS most commonly affects your C2 and C3 vertebrae. Normally, each vertebra is separated by intervertebral disks and cartilage, which adds a cushion between vertebrae and allows them to slide against each other. If you have KFS, some of your vertebrae stick together like a single piece of bone.

The three most common physical features of KFS (you may have none, one or more of these) are:

  • Fusion of cervical vertebrae, which limits neck motion.
  • A short neck.
  • A low hairline at the back of your head.

KFS is a congenital condition, which means it’s something you’re born with.

The syndrome is named for the two physicians who first discovered the condition in the early 1900s.


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How common is Klippel-Feil syndrome (KFS)?

Klippel-Feil syndrome (KFS) happens in about 1 in 40,000 to 42,000 newborns worldwide. It’s slightly more common in women and people assigned female at birth.

How do I know if my child has Klippel-Feil syndrome (KFS)?

Depending on the severity, Klippel-Feil syndrome (KFS) may be visible on ultrasound in the first trimester of pregnancy. If your provider can’t see it during pregnancy and there aren’t any obvious abnormalities at birth, during infancy or childhood, they may not discover it until the teen years or later. Late discovery is rare, however, because of the number of possible symptoms and abnormalities.


Symptoms and Causes

What are the symptoms of Klippel-Feil syndrome (KFS)?

Occasionally, people with Klippel-Feil syndrome (KFS) have few or no symptoms. Most people, however, do have symptoms, which range from mild to severe. Symptoms vary greatly from person to person.

Common signs and symptoms include:

  • Limited range of motion in your neck (most common physical symptom). The fusion of two or more vertebrae in your neck causes this.
  • Low hairline at the back of your head.
  • Short neck.
  • Size and shape difference between the two sides of your face.
  • Instability of the upper cervical spine where it connects to your skull. This can be very dangerous if you get injured, like in a car accident or playing football.
  • Curvature in your spine (scoliosis) in 30% to 50% of people.
  • Headaches.
  • Deafness in 30% of people.
  • Limited back (upper spine) motion.
  • Nerve pain that spreads into your arms or legs.
  • Muscle pain in your neck and/or back.
  • Nerve damage in your neck or back.
  • Narrowing of your spinal space (spinal stenosis), which can damage your spinal cord.
  • Kidney disease in 30% of people.

Other problems include:

  • Hearing problems or deafness.
  • Cleft palate or abnormally shaped palate.
  • Abnormalities in reproductive organs, and urinary tract, heart and lung, rib deformities or arm and leg deformities.
  • Weakness in ligaments in your upper spine-skull junction, which can allow movements to pinch your spinal cord and cause nerve damage.

What causes Klippel-Feil syndrome (KFS)?

Researchers don’t fully know what causes Klippel-Feil syndrome (KFS). Most cases are thought to be sporadic — meaning there’s no family history or obvious genetic cause. In others, changes (mutations) in one of the genes involved in bone and spine development cause the syndrome.

KFS can sometimes also be seen with another disorder or be a side effect of another congenital disease. If it’s a side effect of another congenital disease, KFS happens because of mutations in the genes involved in those disorders.

Some of these medical issues and conditions are:

  • Central nervous system problems and other issues that arise from drinking alcohol while pregnant (fetal alcohol syndrome).
  • Abnormal eye, ear and spine development (Goldenhar syndrome).
  • Abnormal shoulder blade development (Sprengel deformity).
  • Abnormal eye movement (Duane syndrome).
  • Absence of one or both kidneys (renal agenesis).
  • Abnormal eyes, ears and neck vertebrae development (Wildervanck syndrome).
  • Abnormal development in the central nervous system (including Chiari malformation, spina bifida and syringomyelia).


Can Klippel-Feil syndrome (KFS) be inherited?

In most cases, Klippel-Feil syndrome (KFS) isn’t inherited. However, in some cases, mutations in one of three identified genes cause this syndrome. When gene mutation(s) cause KFS, you can inherit the syndrome.

Diagnosis and Tests

How is Klippel-Feil syndrome (KFS) diagnosed?

A healthcare provider makes the diagnosis of Klippel-Feil syndrome (KFS) based on your symptoms, a clinical exam and imaging studies. Providers usually diagnose this syndrome in childhood, and can sometimes even see it in a fetus before birth.

Your healthcare provider will ask about your medical history and family history and perform a physical. During the physical exam, your provider will:

  • Look at your face, neck (to see if it’s short in height), the rest of your spine and your hairline (to see if it’s low at the back of your head).
  • Look for signs of radiculopathy (to see if your cervical spine is pinching a nerve) or myelopathy (to see if compression injured your spinal cord).
  • Check reflexes that your spinal cord and other nerves control.
  • Assess how you walk (your gait).
  • Listen to and feel your chest and belly.

What tests will be done to diagnose this condition?

There aren’t any lab tests that diagnose KFS, but your provider may order laboratory tests to rule out other conditions if you have multiple symptoms. They’ll examine your heart, kidneys and organs of the gastrointestinal tract and urinary tract for abnormalities. They may order a hearing test. Your provider may also discuss genetic testing.

Spine imaging

Your healthcare provider will want to see X-rays, and maybe a computed tomography (CT) scan or magnetic resonance imaging (MRI).

  • X-rays: X-rays can show fused vertebrae and the curve, stability and any other abnormal features of your entire spine.
  • CT scan: A CT scan provides additional details about fused vertebrae and spine structure.
  • MRI scan: An MRI scan helps view soft tissue structures including the spinal cord, disk space, nerve roots and spinal ligaments and finds other abnormalities in any organs in your body.

Management and Treatment

How is Klippel-Feil syndrome (KFS) treated?

Your symptoms determine the treatment. Treatment might include medications and/or physical therapy. You’ll need to understand any risks you have if you’re involved in trauma so you can avoid dangerous activities. Most people with KFS don’t need surgery.

Conservative treatments and medications

The majority of people who don’t need surgery do well with conservative treatments such as using cervical collars, braces and traction. Your provider may order medications to relieve pain and inflammation.


You’re more likely to need surgery if:

  • You have a problem with your nervous system, including your brain, spinal cord and nerves.
  • You have a deformed or unstable spine.
  • You have new muscle weakness. This could be a sign of something more serious related to your spine or spinal cord.
  • You have abnormalities in other organs.

If you have one or more fused cervical vertebrae below C3, close monitoring may be all that’s needed. If you or your child play contact sports, such as hockey or rugby, your healthcare provider may say you can continue to play these sports once you’ve learned how to protect your neck.

If you have any fused cervical vertebrae above C3 (nearest the base of your skull), you should avoid playing contact sports. You’re at greater risk of a dangerous spinal injury.

Your healthcare provider will regularly check your heart and lungs, reproductive system, kidneys and other organs to catch any problems early, manage or treat any changes, or recommend any needed surgery.

Can Klippel-Feil syndrome (KFS) get worse?

Klippel-Feil syndrome (KFS) can worsen over time. If your spine is abnormal, you’re more likely to develop problems as you age, such as degenerative disk issues, which can cause pinched nerves, pain in your back and spine or weakness in your arms or legs.

You’re more prone to injury through falls and blows to your body. Other internal problems may develop over time. This is why it’s important to see your team of healthcare providers as scheduled. They’ll perform check-ups and any needed tests or imaging studies to determine or change treatment.

Does Klippel-Feil syndrome (KFS) affect life expectancy?

Diagnosing Klippel-Feil syndrome (KFS) early is key to managing or treating health problems with surgery or by nonsurgical methods and careful watching over time. By fixing abnormalities and following your healthcare provider’s instructions for protecting your spine, you can usually have a normal life expectancy.

Outlook / Prognosis

What can I expect if I have Klippel-Feil syndrome (KFS)?

Your outcome depends on what your disease looks like (what parts of you are affected) and any other related conditions. Each person is unique. Your healthcare team will discuss your case when they see you at regular intervals. Some people have no symptoms and others have a significant number of symptoms that lower their quality of life.

Your healthcare providers will discuss if you need to do anything to protect your spine, if you can play contact sports or if you need to make other lifestyle changes. They’ll also discuss any need for surgery.

Living With

What type of healthcare professionals might be involved in my care?

The types of healthcare providers who might be involved in your care include:

  • Your regular provider.
  • Pediatric or internal medicine specialist.
  • Neurologist.
  • Neurosurgeon.
  • Orthopaedic surgeon.
  • Oromaxillofacial surgeon.
  • Cardiologist.
  • Gastroenterologist.
  • Nephrologist.
  • Otolaryngologist.
  • Audiologist.
  • Pain management specialist.
  • Physical therapist.

A note from Cleveland Clinic

Klippel-Feil syndrome (KFS) is a rare spinal condition in which two or more vertebrae in your neck join together. The syndrome may be associated with many other spine problems and many other parts of your body can be affected too. However, each person is unique. You may have a mild form of KFS and not have significant symptoms or you may have more severe health issues that require long-term management. Your team of specialists will be with you each step of the way.

Medically Reviewed

Last reviewed on 08/02/2022.

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