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Encephalocele

Summary

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  • Congenital malformation characterised by protrusion of brain tissue and meninges through a defect in the skull
  • Results from failure of neural tube closure during embryonic development
  • Diagnosis based on clinical presentation and neuroimaging findings1

Pathophysiology

  • Occurs due to incomplete closure of the neural tube during weeks 3-4 of embryonic development
  • Classified based on location:
    • Occipital (most common in Western countries)
    • Frontal
    • Parietal
    • Basal
  • Associated with other neural tube defects and genetic syndromes

Demographics

  • Incidence: 1-4 per 10,000 live births worldwide
  • Higher prevalence in Southeast Asia and parts of Africa
  • Risk factors:
    • Maternal folate deficiency
    • Genetic predisposition
    • Environmental factors (e.g., certain medications, toxins)

Diagnosis

  • Prenatal:
    • Maternal serum alpha-fetoprotein screening
    • Ultrasound examination
  • Postnatal:
    • Physical examination
    • Neuroimaging (CT, MRI)
  • Genetic testing to identify associated syndromes

Imaging

  • Ultrasound:
    • Anechoic or mixed echogenic mass protruding through skull defect
    • Visible skull defect
  • CT:
    • Bony defect in skull
    • Herniated brain tissue and CSF
    • 3D reconstruction useful for surgical planning
  • MRI:
    • Gold standard for characterising encephalocele contents
    • T1 and T2-weighted images to assess brain tissue and CSF
    • Helps identify associated brain malformations

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  • 60-year-old patient with longterm epilepsy.
  • Seizure semiology suggesting a temporal lobe origin.
  • MRI showed a small volume of the temporal lobe prolapsed with T2-hyperintense gliotic signal change (red arrow).
  • CT showed a defect in the skull base causing an enlarged foramen ovale.

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  • 60-year-old patient with a longstanding nasal CSF leak.
  • Medial temporal lobe encephalocele due to a defect in the lateral wall of the sphenoid bone.
  • Intracranial hypotension caused shallow subdural collections.

Treatment

  • Surgical repair of the defect; in adults, temporal/sphenoid encephaloceles are repaired for CSF leak or epilepsy

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Cephalohaematoma Doesn't cross suture lines; fluctuant swelling
Sinus pericranii Reduces with pressure or in recumbent position
Dermoid cyst Typically midline; doesn't transilluminate
Meningocele No brain tissue within the sac
Atretic encephalocele Smaller, skin-covered lesion without CSF
Nasal glioma Solid mass, doesn't change size with crying
Teratoma Complex mass with mixed tissue types on imaging
Skull fracture History of trauma; linear lucency on X-ray
Langerhans cell histiocytosis Lytic bone lesions on imaging
Congenital hemangioma Vascular lesion with flow on Doppler ultrasound

  1. A Monteagudo. Posterior Encephalocele. 2020. American journal of obstetrics and gynecology - Open in new tab. ↩