Neurosurgery notes/Paediatrics/Paediatric Syndrome/Larsen syndrome

Larsen syndrome

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Paediatric Syndrome

General

  • Definition: A rare genetic disorder caused by mutations in filamin B and carbohydrate sulfotransferase 3 deficiency, that presents with characteristic findings of ligamentous hyperlaxity, abnormal facial features, cervical kyphosis, and multiple joint dislocations.
  • Diagnosis is made based on family history associated with typical radiographic and clinical features.
  • No commercially available diagnostic test exists due to the variety of genetic mutations.
  • Treatment is usually open reduction for joint dislocations and early posterior spinal fusion for cervical kyphosis to prevent neurological deterioration.

Epidemiology

  • Incidence: 1/100,000

Aetiology

  • Genetics
    • Both AD and AR inheritance patterns
      • AD linked to a mutation of the gene encoding filamin B
      • AR linked to carbohydrate sulfotransferase 3 deficiency

Associated conditions

Orthopaedic manisfestations

  • Hand deformities
  • Dislocations
    • Hips
    • Knees (usually bilateral)
    • Shoulders
    • Elbows (radial head)
  • Clubfeet

Spinal

  • Scoliosis
  • Cervical kyphosis
    • May present with extremity weakness secondary to myelopathy
    • Caused by hypoplasia of the cervical vertebrae

Clinical presentation

Symptoms

  • Patients have normal intelligence

Signs

  • Hypotonia
    • Uncommon but may be due to cervical compression
  • Abnormal facial features
    • Flattened nasal bridge
    • Hypertelorism
    • Prominent forehead
  • Hands
    • Long cylindrical fingers that do not taper
    • Wide distal phalanx at the thumb
  • Elbows
    • Bilateral radial head dislocations may be present
  • Knees
    • Look for bilateral knee dislocations
  • Foot deformities
    • Equinovarus
    • Eqinovalgus
    • Clubfeet
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Imaging

Radiographs

  • AP and lateral of cervical spine
    • During first year of life
    • Prior to any intubation to avoid iatrogenic spinal cord injury
  • AP pelvis and lateral of hips
    • Ultrasound if less than 3 months
  • Findings
    • Hypoplasia of vertebrae
    • Cervical kyphosis with subluxation
    • Hip dislocation

MRI

  • Cervical kyphosis
    • Myelopathy

Treatment

  • Cervical kyphosis
    • Operative
      • Posterior cervical fusion
        • Indications
          • Patients with significant kyphosis but no neurologic deficits
          • Recommended to be performed during the first 18 months of life to prevent neurological deterioration
      • Anterior/posterior cervical decompression and fusion
        • Indications
          • Cervical kyphosis with neurologic deficits