ENCEPHALOCELES

ENCEPHALOCELES
N E U R O N I C U 5 M I N U T E F R I D AY
Andy Stadler, MD
Pediatric Neurosurgery Fellow
July 29, 2016
Discussion Outline
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Case Presentation
Definitions
History
Embryology
Epidemiology
Classification
Diagnosis
Posterior Encephaloceles
Anterior Encephaloceles
Summary
Case Presentation
§  Newborn female with prenatal diagnosis of a cranial abnormality
›  Routine US à prenatal MRI
›  Pregnancy otherwise uncomplicated
›  Full term, elective cesarean section
›  Otherwise healthy
§  Large cystic occipital mass
›  Pulsatile
›  Transilluminates
§  Neurological exam normal for her age, head circumference small
§  CT, MRI, and MRA/MRV obtained
›  Bony defect minimal
›  No major venous involvement
›  Small amount of brain parenchyma herniated into sac
Case Presentation
Case Presentation
Definitions
§  Encephalocele: neural tube defect characterized by herniation of
cerebral tissue, meninges, and CSF outside the confines of the skull
§  Meningocele: herniation of meninges and CSF only
§  Cephalocele: any combination of these intracranial elements
§  Cranium bifidum occultum: midline or paramedian calvarial defect not
associated with brain, meningeal, or CSF prolapse
History
§  Ancient sculptures and medieval art
show earliest depictions of
encephaloceles
§  Petrus Forrestus (1590): earliest
written description
§  J.F.C. Corvinus (1749): first
monograph on encephaloceles
§  Pathogenesis debated throughout the
19th century, with multiple theories
proposed
Embryology
§  Pathogenesis is poorly understood
§  Possibly related to an error in
mesodermal differentiation, with focal
failure of the structures arising from the
paraxial mesoderm
§  More recently theorized to be secondary
to a failure of neuroectodermal
disjunction
›  Normal migration of the paraxial
mesoderm prevented
§  Possible environmental contribution
§  AR and teratogenic syndromes
§  Familial association reported but rare
Epidemiology
§  Overall incidence impossible to state
§  Distribution varies by geography and race
›  North America, Europe, and northern Asia: occipital encephaloceles in
0.8-4.0 per 10,000 live births, 70% female
›  Southeast Asia: sincipital encephaloceles in 1 in 5000 live births
§  Basal encephaloceles 10%, temporal <1%
§  10-15% of all neural tube defects
Jimenez DF, Principles and Practice of Pediatric Neurosurgery (2015)
Classification
§  Primary vs secondary
§  Location
›  Occipital: supratorcular, infratorcular
›  Occipitocervical
›  Parietal: interparietal, anterior/posterior fontanelle
›  Sicipital: interfrontal, nasofrontal, nasoethmoidal, nasoorbital,
cranial cleft
›  Basal: transethmoidal, transsphenoidal, sphenoethmoidal,
sphenomaxillary, sphenoorbital, sphenopharyngeal, temporal,
endaural
§  Associated syndromes
Associated Anomalies
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Tessier facial cleft
Craniostenosis
Dandy-Walker cysts
Chiari malformation
Ectrodactyly
Hemifacial microsomia
Hypothalamic-pituitary dysfunction
Iniencephaly
Klippel-Feil syndrome
Myelomeningocele
Hypertelorism
Optic nerve abnormalities
Holoprosencephaly
Associated Syndromes
Jimenez DF, Principles and Practice of Pediatric Neurosurgery (2015)
Associated Syndromes
Jimenez DF, Principles and Practice of Pediatric Neurosurgery (2015)
Diagnosis
§  Prenatal scans
§  Amniocentesis results may be normal
§  Prenatal MRI
›  Routine prenatal imaging may be normal
with small defects
§  Postnatal MRI
›  Often including MRA/MRV
§  Craniofacial CT
Posterior Encephaloceles
§  Occipital encephaloceles generally apparent at birth
§  Small encephaloceles may have minimal clinical correlate
§  Larger lesions can result in
microcrania, cranial nerve
deficits, spasticity, blindness,
developmental delays
§  Larger lesions diagnosed
prenatally may require
cesarean section
§  Size distribution varies
›  >20cm – 16%
›  15-20cm – 14%
›  10-15cm – 12%
›  5-10cm – 30%
›  <5cm – 28%
Posterior Encephaloceles – Associated Findings
Hydrocephalus: 16-65% occurance
Skull base deformity and microcephaly: 9-27%
Falx and tentorium often in abnormal position
May involve posterior elements of adjacent vertebrae
Occipital encephaloceles may be in combination with multiple
extracranial abnormalities, suggesting error in developmental migratory
processes
§  Other findings: brainstem kinking, inverted cerebellum, temporal lobe
herniation, occipital lobe herniation, dysgenesis of the cecum,
dysgenesis of the vermis, corpus callosum dysplasia, thamalic fusion,
hydromyelia
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Posterior Encephaloceles – Surgical Management
§  Unless rupture of the sac with CSF leakage or exposed brain parenchyma,
repair may be elective
§  Prone positioning
§  Careful dissection to develop plane around the cyst
§  Exploration of the cyst
§  Debridement of necrotic tissue, intracranial reduction of viable tissue
§  Transection of the cyst flush with the cranial defect and primary closure
§  Often bone defect is small enough to not require intervention
§  “Expansion cranioplasties” may accommodate larger amounts of viable
herniated neural tissue
§  Larger bony defects may require cranioplasty
›  Split-thickness bone grafting if older
›  Consider staged cranioplasty in younger patients
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Surgical Management
Posterior Encephaloceles – Prognosis
§  Posterior encephaloceles predict worse outcomes than sincipital or basal
§  Many factors can negatively affect prognosis
›  Hydrocephalus
›  Amount of parenchymal within the defect
›  Seizure disorder
›  Vascular/venous involvement
›  Other brain abnormalities
§  Hydrocephalus and seizure disorders are more common with occipital
encephaloceles
§  Overall prognosis for occipital encephaloceles
›  83% with significant mental or physical impairments
›  17% with no significant deficits
›  Half of all patients are able to function independently
Anterior Encephaloceles
§  May not manifest until later in childhood or adulthood
§  Sincipital encephaloceles generally visible at birth as an eccentric facial
swelling that enlarges with crying/Valsalva
§  Nasoethmoidal may be mistaken for nasal polyps
§  Basal encephaloceles typically present with symptoms of nasal
obstruction
Anterior Encephaloceles
Anterior Encephaloceles – Sincipital
Anterior Encephaloceles – Nasoethmoidal
Anterior Encephaloceles – Basal
Summary
§  Encephaloceles are relatively rare neurodevelopmental lesions
§  Improved understanding of the pathogenesis and etiology of these
lesions will likely follow molecular genetic analysis
§  Anterior and posterior encephaloceles have varied presentation and
operative considerations, but with similar surgical goals
§  Prognosis related to location and extent of the lesion