Klippel-Feil Syndrome

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Definition: Klippel-Feil Syndrome (KFS) is a congenital condition characterized by the abnormal fusion of two or more cervical vertebrae. It results from a failure of normal segmentation of cervical somites during the 3rd to 8th weeks of gestation.

Epidemiology:

• Prevalence: Estimated at 1 in 40,000 to 42,000 births (likely under-reported as asymptomatic cases exist).
• Gender: Slight female predominance (60%).
• Genetics:
  • Most cases are sporadic.
  • Autosomal Dominant and Recessive forms exist (GDF6, GDF3, MEOX1 mutations identified).

Clinical Triad (The Classic Description):

1. Low Posterior Hairline.
2. Short Neck.
3. Limited Cervical Range of Motion. Note: This classic triad is present in less than 50% of patients.

Natural History:

• Many patients with limited fusion (Type I) are asymptomatic and live normal lives.
• Symptomatic patients present with neck pain, radiculopathy, or myelopathy, usually in the 2nd or 3rd decade due to degeneration at adjacent overdrive segments.

Embryology:

• Somitogenesis: The vertebral column forms from sclerotomes.
• Segmentation: Requires precise regulation (Notch signaling pathway).
• Failure: KFS is a Failure of Segmentation. (Contrast with Hemivertebra which is Failure of Formation).

Biomechanics of Fusion:

• The "Fused" Segment: Is immobile.
• The "Adjacent" Segment: Must compensate to maintain head motion.
• Hyper-mobility: The level above or below the fusion experiences increased stress and range of motion.
• Instability: This hyper-mobility can lead to ligamentous laxity and frank instability.
• Wash-boarding: On flexion-extension views, the segment moves excessively compared to normal.

Common Levels:

• C2-C3 Fusion: Most common. Often autosomal dominant.
• C5-C6 Fusion: Second most common. Autosmal recessive association.
• Occipitocervical: Rare but dangerous.

History:

• Appearance: Parents notice short neck or asymmetry.
• Function: Difficulty turning head (turning whole body).
• Pain: Neck pain (mechanical) or radicular symptoms (nerve compression).
• Neuro: Weakness, clumsiness (Myelopathy signs).

Physical Examination:

• Inspection:
  • Short neck appearance ("Head sits on shoulders").
  • Low hairline.
  • Webbed neck (Pterygium colli) - Differentiate from Turner Syndrome.
  • Torticollis or facial asymmetry.
  • Sprengel's deformity (High scapula).
• Range of Motion:
  • Restricted rotation and lateral bending usually.
  • Flexion/Extension may be preserved if segments are open.
• Neurology:
  • Reflexes (Hyperreflexia? Hoffman's? indicates Myelopathy).
  • Strength and Sensation.
  • Mirror Movements (Synkinesis): Involuntary movement of one hand when the other moves. Indicates failure of decussation of corticospinal tracts.

Screening:

• MUST examine for other anomalies (Heart murmur, Scoliosis check).

Plain Radiographs:

• Views: AP, Lateral, Open Mouth Odontoid.
• Dynamic: Flexion / Extension views are Critical.
  • Look for instability (greater than 3.5mm translation or greater than 11 degrees angulation).
  • Look for hyper-mobility at adjacent segments.
• Findings:
  • WASP waist appearance (narrowing at fused disc space).
  • Loss of disc height.
  • Fusion of posterior elements (facets/lamina).

Advanced Imaging:

• CT Scan:
  • Best for bony architecture.
  • Define extent of fusion (anterior vs posterior).
  • Surgical planning.
• MRI Spine (Total):
  • Mandatory if neuro signs or before surgery.
  • Assess cord compression (stenosis at adjacent levels).
  • Screen for Chiari malformation, Syringomyelia, Diastematomyelia.
• Renal Ultrasound:
  • Screen for agenesis/anomalies (30%).

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Surgical Tips

• Vascular Study: Pre-operative CTA/MRA is recommended to map the Vertebral Arteries. They often have aberrant courses (enter at C4 or C5) in KFS.
• Intubation: Difficult airway anticipated (limited neck extension). Use Fiberoptic.

Prognosis by Type

• Type I (Single block): Usually benign natural history. May remain asymptomatic throughout life.
• Type II (Long segments): High rate of myelopathy/radiculopathy in adulthood due to hypermobility at unfused segments.
• Type III (Multiple non-contiguous): Variable prognosis depending on associated anomalies.

Long-Term Considerations

Patients with Klippel-Feil syndrome face unique long-term challenges:

• Accelerated adjacent segment disease: Open segments bear increased stress, leading to early degeneration
• Sports participation: Patients with stable spines who avoid contact sports generally have good function
• Occupational considerations: May need activity modification for jobs involving heavy lifting or neck strain
• Life expectancy: Generally normal unless associated with severe cardiac or renal anomalies

Surgical Outcomes

• Fusion success rate: Generally high (greater than 90%) for posterior cervical fusion
• Symptom relief: Good pain relief and neurological improvement in appropriately selected patients
• Adjacent segment disease: Risk of progression despite successful fusion
• Revision surgery: May be required for pseudarthrosis or adjacent level pathology

Multidisciplinary Care

Optimal management of Klippel-Feil syndrome requires a coordinated team approach with input from orthopaedics, paediatrics, cardiology, nephrology, and genetics to address the full spectrum of associated anomalies and ensure comprehensive patient care.

• Epidemiology: Access to MRI and genetic testing (e.g., GDF6) is available in major centers.
• Referral: Usually managed in tertiary pediatric spine centers (Children's Hospitals).
• Sports: Rugby is huge in Australia. Strict adherence to Torg guidelines and counselling against scrum participation for KFS patients is critical.
• NDIS: Severe cases with neurologic deficit may qualify for support.