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Cephalocele
Usha D. Nagaraj, MD
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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
              • 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
                • 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

            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

                                          1. Khodarahmi I et al: Imaging spectrum of calvarial abnormalities. Radiographics. 41(4):1144-63, 2021
                                          2. Nagaraj UD et al: Prenatal evaluation of the Sakoda complex. Pediatr Radiol. 49(13):1843-7, 2019
                                          3. Yucetas SC et al: A retrospective analysis of neonatal encephalocele predisposing factors and outcomes. Pediatr Neurosurg. 52(2):73-6, 2017
                                          4. Demir MK et al: Atretic cephaloceles: a comprehensive analysis of historical cohort. Childs Nerv Syst. 32(12):2327-37, 2016
                                          5. Boppel T et al: Excavating Meckel's cave: cavum-trigeminale-cephaloceles (CTCs). J Neuroradiol. 42(3):156-61, 2015
                                          6. Morone PJ et al: Temporal lobe encephaloceles: a potentially curable cause of seizures. Otol Neurotol. 36(8):1439-42, 2015
                                          7. Copp AJ et al: Neural tube defects: recent advances, unsolved questions, and controversies. Lancet Neurol. 12(8):799-810, 2013
                                          8. 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
                                          9. Barkovich et al: Pediatric Neuroimaging: 5th edition. Lippincott Williams & Wilkins. 501-21, 2012
                                          10. Bui CJ et al: Institutional experience with cranial vault encephaloceles. J Neurosurg. 107(1 Suppl):22-5, 2007
                                          11. Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol. 36(7):647-62; quiz 726-7, 2006
                                          12. Rowland CA et al: Are encephaloceles neural tube defects? Pediatrics. 118(3):916-23, 2006
                                          13. Sdano MT et al: Temporal bone encephaloceles. Curr Opin Otolaryngol Head Neck Surg. 13(5):287-9, 2005
                                          14. 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
                                          15. Lowe LH et al: Midface anomalies in children. Radiographics. 20(4):907-22; quiz 1106-7, 1112, 2000
                                          16. Patterson RJ, et al: Atretic parietal cephaloceles revisited: an enlarging clinical and imaging spectrum? AJNR 19:791-5, 1998
                                          Related Anatomy
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                                          Related Differential Diagnoses
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                                          References
                                          Tables

                                          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
                                                      • 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
                                                        • 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

                                                    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

                                                                                  1. Khodarahmi I et al: Imaging spectrum of calvarial abnormalities. Radiographics. 41(4):1144-63, 2021
                                                                                  2. Nagaraj UD et al: Prenatal evaluation of the Sakoda complex. Pediatr Radiol. 49(13):1843-7, 2019
                                                                                  3. Yucetas SC et al: A retrospective analysis of neonatal encephalocele predisposing factors and outcomes. Pediatr Neurosurg. 52(2):73-6, 2017
                                                                                  4. Demir MK et al: Atretic cephaloceles: a comprehensive analysis of historical cohort. Childs Nerv Syst. 32(12):2327-37, 2016
                                                                                  5. Boppel T et al: Excavating Meckel's cave: cavum-trigeminale-cephaloceles (CTCs). J Neuroradiol. 42(3):156-61, 2015
                                                                                  6. Morone PJ et al: Temporal lobe encephaloceles: a potentially curable cause of seizures. Otol Neurotol. 36(8):1439-42, 2015
                                                                                  7. Copp AJ et al: Neural tube defects: recent advances, unsolved questions, and controversies. Lancet Neurol. 12(8):799-810, 2013
                                                                                  8. 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
                                                                                  9. Barkovich et al: Pediatric Neuroimaging: 5th edition. Lippincott Williams & Wilkins. 501-21, 2012
                                                                                  10. Bui CJ et al: Institutional experience with cranial vault encephaloceles. J Neurosurg. 107(1 Suppl):22-5, 2007
                                                                                  11. Hedlund G: Congenital frontonasal masses: developmental anatomy, malformations, and MR imaging. Pediatr Radiol. 36(7):647-62; quiz 726-7, 2006
                                                                                  12. Rowland CA et al: Are encephaloceles neural tube defects? Pediatrics. 118(3):916-23, 2006
                                                                                  13. Sdano MT et al: Temporal bone encephaloceles. Curr Opin Otolaryngol Head Neck Surg. 13(5):287-9, 2005
                                                                                  14. 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
                                                                                  15. Lowe LH et al: Midface anomalies in children. Radiographics. 20(4):907-22; quiz 1106-7, 1112, 2000
                                                                                  16. Patterson RJ, et al: Atretic parietal cephaloceles revisited: an enlarging clinical and imaging spectrum? AJNR 19:791-5, 1998