Klippel-Feil Syndrome

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Introduction

Klippel-Feil syndrome (KFS) was first described in 1912 by French physicians Maurice Klippel and André Feil. It is a complex condition presenting due to abnormal fusion of two or more cervical vertebrae, caused by a failure in the normal segmentation in early foetal development. This condition leads to a characteristic appearance of a shortened neck, low hairline, and limited neck mobility.

X-ray showing fused cervical vertebrae as seen in Klippel–Feil syndrome

Aetiology

Researchers have identified pathological variants in various genes along with environmental factors that can lead to KFS.

• The proteins produced by the GDF6, GDF3, and MEOX1 genes are responsible for the formation of bones and joints, as well as separation of spinal vertebrae during early development. Any variation results in a reduction in protein production, causing KFS; however, it is unclear how this shortage leads to separation and fusion of the cervical vertebrae.
• In many cases, the exact cause of KFS is not known. Researchers suspect that a combination of genetic factors and environmental factors, such as a disruption of blood flow during critical periods of development, may play a role.

Classification

The Samartzis classification system divides KFS into three types based on the number and level of vertebral fusion(s) and can be used by physicians to estimate the severity and presentation of symptoms in this subset of patients. The classification is as follows:

• Type I patients with a single congenitally fused cervical segment
• Type II patients with multiple non-contiguous, congenitally fused cervical segments
• Type III patients with contiguous, congenitally fused cervical segments

Epidemiology

KFS is a rare congenital condition occurring in approximately 1 in 40,000–42,000 newborns worldwide, with a slight female predominance. CT-based studies suggest the true prevalence is higher than the birth incidence, given that a larger number of individuals remain asymptomatic.

Clinical Presentation

Clinical features in KFS vary in severity depending on the extent and level of vertebral fusion. The following features may be present:

• Fusion of two or more spinal bones in the neck
• Short neck and low hairline
• Torticollis
• Congenital scoliosis
• Spina bifida
• Kidney, rib, and heart malformations
• Respiratory problems
• Syndactyly (webbed fingers) and hypoplastic thumb (abnormality of the thumb)
• Synkinesis or mirror movement (movement in one hand involuntarily mimics the deliberate movement of the other hand)
• Sprengel's deformity (scapula is congenitally elevated, causing restricted shoulder movements)[7]
• Hearing issues

The classic complete clinical triad of the low hairline, short neck, and restricted neck motion is seen in almost 50% of people with KFS.

Woman with Klippel–Feil syndrome

Differential Diagnosis

Several conditions may present with similar cervical spine findings or features, and should be considered when evaluating a patient with suspected KFS. The following are possible differential diagnoses for KFS:

• Healing osteomyelitis or discitis
• Previous fusion without instrumentation
• Juvenile idiopathic arthritis
• Ankylosing spondylitis

Diagnostic Procedures

KFS is present from birth but often goes unnoticed until later in life when symptoms worsen or become more obvious. It is typically diagnosed based on a clinical examination, symptoms and diagnostic studies (Plain X-rays, MRI, CT Scan, Ultrasound, or genetic testing).

• Plain X-rays may be obtained in older patients with Klippel-Feil syndrome to assess the extent of cervical vertebral fusion and the involvement of the ribs and other spinal segments.
• MRI is most useful in people who present with neurological deficits to evaluate soft tissue structures and spinal malformations.
• CT Scans in sagittal and coronal views provide detailed insights into spinal pathology.
• US may reveal KFS-related cardiac, gastrointestinal, and renal anomalies.
• In familial cases, molecular genetic testing (for GDF6, GDF3, MEOX1 variants) may be indicated.

Treatment

There is no curative treatment for KFS; management is symptomatic and tailored to the individual's presentation.

• Lifestyle modifications include avoidance of contact sports and high-impact activities that risk cervical injury.[9]
• Neck braces and traction may provide symptomatic relief.
• Patients with persistent neurological pain, myelopathy, new-onset muscle group weakness, and documented spinal instability are candidates for surgical intervention.

Physiotherapy Management

Physiotherapy in KFS aims to manage pain, maintain or improve function, and prevent secondary complications.

The following are the possible interventions tailored to manage symptom severity and individual presentation.

• Postural exercises and strengthening of neck, shoulder, and periscapular musculature are recommended in most patients to maintain mobility and strength.
• For axial symptoms and radiculopathy, physiotherapists can use soft tissue massage and mobilisation techniques while avoiding spinal manipulation to manage the symptoms.
• Low-intensity exercises such as aerobic (e.g. walking) and aquatic exercise (e.g. swimming) to prevent secondary complications.
• Regaining shoulder and neck range of motion when there is coexistence of Torticollis and Sprengel's deformity.
• Strengthening/stretching of weak/tight structures in cases coexisting with scoliosis.
• Breathing exercises for maintenance of respiratory functions.
• A home exercise program consisting of self-correction and active exercises for the shoulder and neck to maintain an improved state and thereby creating self-awareness.
• Physiotherapy in combination with non-steroidal medications could be useful to prevent degenerative changes.

Prognosis

In the absence of neurological deficit and spinal instability, people with KFS can be well managed by conservative treatment. The prognosis for most cases is good if the condition is diagnosed early in life. The prognosis varies with the severity and the number of fused segments.

However, when a person with KFS has several fused vertebrae, the risk of osteoarthritic changes increases due to the immobile joint. The superior joint likely undergoes degenerative changes with formation of osteophytes. This can lead to radiculopathy and/or myelopathy.

Summary

KFS is a rare and congenital cervical spine disorder characterised by short neck, low hairline, and decreased neck mobility. It can also be associated with various other congenital disorders. Early diagnosis, continued monitoring for complications, and treatment are important to successful long-term outcomes.