Klippel-Feil Syndrome
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Direct answer
Klippel-Feil syndrome is a congenital disorder in which two or more cervical vertebrae are fused, classically producing a short neck, a low posterior hairline and restricted neck movement. It is often accompanied by Sprengel deformity, renal, cardiac and neural axis anomalies, so every child needs a wider search. The Feil classification grades the pattern of cervical fusion, and the level of involvement shapes the assessment.
What you must remember
- Congenital fusion: a failure of normal cervical segmentation in early embryonic life, leaving fused vertebral bodies rather than separate segments.
- Classic triad: short neck, low posterior hairline and restricted neck movement, with all three present in only a minority of patients.
- Sprengel deformity: a high, small scapula that is a frequent accompaniment and should prompt a search for other fusions.
- Renal anomalies: agenesis, ectopia and horseshoe kidney, so renal ultrasonography forms part of the work-up.
- Cardiac and neural anomalies: congenital heart disease, Chiari malformation and syringomyelia can accompany the fusion, and MRI of the craniocervical junction is important.
- Other associations: sensorineural deafness, Duane anomaly and mirror movements are recognised features.
- Feil classification: Type I is a massive cervical and upper thoracic fusion, Type II involves one or two interspaces and Type III combines cervical fusion with a lower thoracic or lumbar fusion.
Grading the fusion and the associated anomalies
A 9-year-old girl has a short neck, a low hairline and limited neck movement. Radiographs show fused cervical bodies, and the plan must address the spine and the associated organ systems together.
| Feil type | Fusion pattern | Typical associations | Practical concern |
|---|---|---|---|
| Type I | One fused mass of cervical and upper thoracic spine | Often severe, with multiple other anomalies | Very restricted neck movement and a greater risk of neural compromise |
| Type II | One or two cervical interspaces fused | Variable, including renal and hearing anomalies | Milder restriction, often discovered incidentally |
| Type III | Cervical fusion combined with lower thoracic or lumbar fusion | Scoliosis and lower spinal anomalies | Deformity progression needs follow-up |
The Feil classification is descriptive rather than a precise predictor of outcome, so the examiner should record the fusion level, the spinal alignment and the affected organ systems. Standing whole-spine radiographs and craniocervical MRI are then used to plan the work-up. Flexion-extension films are added when instability is suspected, before any contact sport or manipulation is allowed.
Where the exam tries to catch you
Examiners test the triad, the associated anomalies and the features that are easily confused with it.
- Trap: treating Sprengel deformity as a separate shoulder problem. Correct: a high scapula is a frequent accompaniment of Klippel-Feil syndrome, so it should prompt a search for cervical fusion and renal or cardiac anomalies.
- Trap: assuming the spine is the only system involved. Correct: renal ultrasonography, echocardiography and hearing assessment are part of the evaluation, since these anomalies are commonly associated.
- Trap: dismissing neck pain or neurological signs as incidental. Correct: craniocervical instability and cord compression need MRI, because a neurological deficit changes the management.
Frequently asked questions
What is the classic triad of Klippel-Feil syndrome?
The classic triad of Klippel-Feil syndrome is a short neck, a low posterior hairline and restricted neck movement. All three features are seen in only a minority of affected children, so the diagnosis is often made from cervical fusion on radiographs.
Which systems must be screened in Klippel-Feil syndrome?
Klippel-Feil syndrome requires screening of the kidneys, heart, nervous system, hearing and shoulder girdle. Renal ultrasonography, echocardiography, MRI of the craniocervical junction and audiometry are commonly used to detect the recognised associations.
What does the Feil classification describe in Klippel-Feil syndrome?
The Feil classification describes the pattern of cervical fusion in Klippel-Feil syndrome, grading it as a massive fusion, a fusion of one or two interspaces, or a cervical fusion combined with a lower thoracic or lumbar fusion. It is descriptive rather than a precise predictor of outcome, so the level of fusion should always be recorded.
Why should a Sprengel deformity prompt a search for Klippel-Feil syndrome?
A Sprengel deformity is a congenital elevation and hypoplasia of the scapula, and it is a frequent accompaniment of Klippel-Feil syndrome. Its presence should therefore prompt a search for cervical fusion and other associated anomalies.