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KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Definitions
- Extracranial extension of intracranial contents through defect in skull; categorized by contents & location
- Congenital is more common than acquired
- Congenital forms are typically sporadic, though chromosomal (trisomy 13 & 18), syndromic (Meckel-Gruber), & disruptive (amniotic band) etiologies have been described
- Acquired forms may be due to trauma, surgery, infection, or Gorham-Stout
- Congenital is more common than acquired
- Contents
- Cephalocele: Broad term for any focal extracranial extension of intracranial contents
- Meningocele: Meninges & CSF only
- Encephalocele: Brain, meninges, CSF
- a.k.a. meningoencephalocele
- Meningoencephalocystocele: Ventricle, brain, meninges, CSF
- Atretic cephalocele: Meningeal & neuroglial elements retain fibrous connection to intracranial compartment, often without significant protrusion through defect
- Locations
- Occipital: Most common location, up to 80% of cases
- Supra- &/or infratentorial structures in cephalocele, including tentorium cerebelli & dural venous sinuses
- Occipitocervical form (Chiari 3): Very rare
- Involving occipital bone, foramen magnum, & upper cervical spine (spinal dysraphism)
- Original Chiari 3 description: Upper cervical spinal dysraphism with protruding encephalocele containing herniated hindbrain
- Associated intracranial findings of Chiari malformation, including "lemon" calvarium, callosal hypogenesis, tectal beaking
- Frontoethmoidal/sincipital/anterior: 15% (↑ in Southeast Asia)
- Nasoethmoidal: Most common form; defect between nasal bone & nasal cartilage (through foramen cecum)
- Nasofrontal/frontonasal: Defect between frontal & nasal bones (through fonticulus frontalis)
- Nasoorbital: Least common form; defect at junction of maxilla (anterior) & lacrimal bone with lamina papyracea of ethmoid bone (posterior)
- Parietal: 10% (↑ in Japan at 38%)
- Atretic parietal cephalocele is most common
- Midline posterior parietal scalp mass over small bony defect, elevation of falx/tentorial junction, persistent falcine venous sinus, fibrous tract splits superior sagittal sinus
- Majority have benign clinical course
- Parietal meningoencephaloceles are uncommon
- Usually associated with significant brain anomalies → poor prognosis
- Atretic parietal cephalocele is most common
- Basal/nasopharyngeal: Up to 10% of cases
- Transethmoidal: Defect in ethmoids only with mass in anterior nasal cavity
- Transsphenoidal/sphenopharyngeal: Defect in sphenoid bone only; usually extends into nasopharynx but can also be confined to sphenoid sinuses
- Sphenoethmoidal: Through sphenoid & ethmoid bones with mass in posterior nasal cavity
- Sphenoorbital: Defect through superior orbital fissure with unilateral exophthalmos; rare cases associated with neurofibromatosis type 1
- Sphenomaxillary: Very rare, 1-2 case reports
- Remaining calvarium: Rare
- Interfrontal
- Interparietal
- Anterior fontanelle
- Posterior fontanelle
- Temporal (lateral)
- Mastoid &/or petrous temporal bone: Rare
- Cavum trigeminale: Rare
- Occipital: Most common location, up to 80% of cases
- Extracranial extension of intracranial contents through defect in skull; categorized by contents & location
IMAGING
General Features
CT Findings
MR Findings
Ultrasonographic Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
- Khodarahmi I et al: Imaging spectrum of calvarial abnormalities. Radiographics. 41(4):1144-63, 2021
- Nagaraj UD et al: Prenatal evaluation of the Sakoda complex. Pediatr Radiol. 49(13):1843-7, 2019
- Yucetas SC et al: A retrospective analysis of neonatal encephalocele predisposing factors and outcomes. Pediatr Neurosurg. 52(2):73-6, 2017
- Demir MK et al: Atretic cephaloceles: a comprehensive analysis of historical cohort. Childs Nerv Syst. 32(12):2327-37, 2016
- Boppel T et al: Excavating Meckel's cave: cavum-trigeminale-cephaloceles (CTCs). J Neuroradiol. 42(3):156-61, 2015
- Morone PJ et al: Temporal lobe encephaloceles: a potentially curable cause of seizures. Otol Neurotol. 36(8):1439-42, 2015
- Copp AJ et al: Neural tube defects: recent advances, unsolved questions, and controversies. Lancet Neurol. 12(8):799-810, 2013
- Tirumandas M et al: Nasal encephaloceles: a review of etiology, pathophysiology, clinical presentations, diagnosis, treatment, and complications. Childs Nerv Syst. 29(5):739-44, 2013
- Barkovich et al: Pediatric Neuroimaging: 5th edition. Lippincott Williams & Wilkins. 501-21, 2012
- Bui CJ et al: Institutional experience with cranial vault encephaloceles. J Neurosurg. 107(1 Suppl):22-5, 2007
- Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol. 36(7):647-62; quiz 726-7, 2006
- Rowland CA et al: Are encephaloceles neural tube defects? Pediatrics. 118(3):916-23, 2006
- Sdano MT et al: Temporal bone encephaloceles. Curr Opin Otolaryngol Head Neck Surg. 13(5):287-9, 2005
- Moron FE et al: Lumps and bumps on the head in children: use of CT and MR imaging in solving the clinical diagnostic dilemma. Radiographics. 24(6):1655-74, 2004
- Lowe LH et al: Midface anomalies in children. Radiographics. 20(4):907-22; quiz 1106-7, 1112, 2000
- Patterson RJ, et al: Atretic parietal cephaloceles revisited: an enlarging clinical and imaging spectrum? AJNR 19:791-5, 1998
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References
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Tables
KEY FACTS
Terminology
Imaging
Top Differential Diagnoses
Clinical Issues
Diagnostic Checklist
TERMINOLOGY
Definitions
- Extracranial extension of intracranial contents through defect in skull; categorized by contents & location
- Congenital is more common than acquired
- Congenital forms are typically sporadic, though chromosomal (trisomy 13 & 18), syndromic (Meckel-Gruber), & disruptive (amniotic band) etiologies have been described
- Acquired forms may be due to trauma, surgery, infection, or Gorham-Stout
- Congenital is more common than acquired
- Contents
- Cephalocele: Broad term for any focal extracranial extension of intracranial contents
- Meningocele: Meninges & CSF only
- Encephalocele: Brain, meninges, CSF
- a.k.a. meningoencephalocele
- Meningoencephalocystocele: Ventricle, brain, meninges, CSF
- Atretic cephalocele: Meningeal & neuroglial elements retain fibrous connection to intracranial compartment, often without significant protrusion through defect
- Locations
- Occipital: Most common location, up to 80% of cases
- Supra- &/or infratentorial structures in cephalocele, including tentorium cerebelli & dural venous sinuses
- Occipitocervical form (Chiari 3): Very rare
- Involving occipital bone, foramen magnum, & upper cervical spine (spinal dysraphism)
- Original Chiari 3 description: Upper cervical spinal dysraphism with protruding encephalocele containing herniated hindbrain
- Associated intracranial findings of Chiari malformation, including "lemon" calvarium, callosal hypogenesis, tectal beaking
- Frontoethmoidal/sincipital/anterior: 15% (↑ in Southeast Asia)
- Nasoethmoidal: Most common form; defect between nasal bone & nasal cartilage (through foramen cecum)
- Nasofrontal/frontonasal: Defect between frontal & nasal bones (through fonticulus frontalis)
- Nasoorbital: Least common form; defect at junction of maxilla (anterior) & lacrimal bone with lamina papyracea of ethmoid bone (posterior)
- Parietal: 10% (↑ in Japan at 38%)
- Atretic parietal cephalocele is most common
- Midline posterior parietal scalp mass over small bony defect, elevation of falx/tentorial junction, persistent falcine venous sinus, fibrous tract splits superior sagittal sinus
- Majority have benign clinical course
- Parietal meningoencephaloceles are uncommon
- Usually associated with significant brain anomalies → poor prognosis
- Atretic parietal cephalocele is most common
- Basal/nasopharyngeal: Up to 10% of cases
- Transethmoidal: Defect in ethmoids only with mass in anterior nasal cavity
- Transsphenoidal/sphenopharyngeal: Defect in sphenoid bone only; usually extends into nasopharynx but can also be confined to sphenoid sinuses
- Sphenoethmoidal: Through sphenoid & ethmoid bones with mass in posterior nasal cavity
- Sphenoorbital: Defect through superior orbital fissure with unilateral exophthalmos; rare cases associated with neurofibromatosis type 1
- Sphenomaxillary: Very rare, 1-2 case reports
- Remaining calvarium: Rare
- Interfrontal
- Interparietal
- Anterior fontanelle
- Posterior fontanelle
- Temporal (lateral)
- Mastoid &/or petrous temporal bone: Rare
- Cavum trigeminale: Rare
- Occipital: Most common location, up to 80% of cases
- Extracranial extension of intracranial contents through defect in skull; categorized by contents & location
IMAGING
General Features
CT Findings
MR Findings
Ultrasonographic Findings
Imaging Recommendations
DIFFERENTIAL DIAGNOSIS
PATHOLOGY
General Features
Gross Pathologic & Surgical Features
CLINICAL ISSUES
Presentation
Demographics
Natural History & Prognosis
Treatment
DIAGNOSTIC CHECKLIST
Consider
Image Interpretation Pearls
Reporting Tips
Selected References
- Khodarahmi I et al: Imaging spectrum of calvarial abnormalities. Radiographics. 41(4):1144-63, 2021
- Nagaraj UD et al: Prenatal evaluation of the Sakoda complex. Pediatr Radiol. 49(13):1843-7, 2019
- Yucetas SC et al: A retrospective analysis of neonatal encephalocele predisposing factors and outcomes. Pediatr Neurosurg. 52(2):73-6, 2017
- Demir MK et al: Atretic cephaloceles: a comprehensive analysis of historical cohort. Childs Nerv Syst. 32(12):2327-37, 2016
- Boppel T et al: Excavating Meckel's cave: cavum-trigeminale-cephaloceles (CTCs). J Neuroradiol. 42(3):156-61, 2015
- Morone PJ et al: Temporal lobe encephaloceles: a potentially curable cause of seizures. Otol Neurotol. 36(8):1439-42, 2015
- Copp AJ et al: Neural tube defects: recent advances, unsolved questions, and controversies. Lancet Neurol. 12(8):799-810, 2013
- Tirumandas M et al: Nasal encephaloceles: a review of etiology, pathophysiology, clinical presentations, diagnosis, treatment, and complications. Childs Nerv Syst. 29(5):739-44, 2013
- Barkovich et al: Pediatric Neuroimaging: 5th edition. Lippincott Williams & Wilkins. 501-21, 2012
- Bui CJ et al: Institutional experience with cranial vault encephaloceles. J Neurosurg. 107(1 Suppl):22-5, 2007
- Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol. 36(7):647-62; quiz 726-7, 2006
- Rowland CA et al: Are encephaloceles neural tube defects? Pediatrics. 118(3):916-23, 2006
- Sdano MT et al: Temporal bone encephaloceles. Curr Opin Otolaryngol Head Neck Surg. 13(5):287-9, 2005
- Moron FE et al: Lumps and bumps on the head in children: use of CT and MR imaging in solving the clinical diagnostic dilemma. Radiographics. 24(6):1655-74, 2004
- Lowe LH et al: Midface anomalies in children. Radiographics. 20(4):907-22; quiz 1106-7, 1112, 2000
- Patterson RJ, et al: Atretic parietal cephaloceles revisited: an enlarging clinical and imaging spectrum? AJNR 19:791-5, 1998
