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Get Wise About Cracks: A
Pictorial Review of the Pediatric
Skull Base eEdE-203
Anna Thomas MD, John Egelhoff DO,
John Curran MD, Jeffrey Miller MD,
Richard Towbin MD.
DISCLOSURES:
• None
Objectives
1. Review the normal anatomic landmarks of the
skull base and its 3 main divisions.
2. Review normal development and progression of
ossification of the different divisions of the skull
base.
3. Review normal skull base lucencies and foramina
of the pediatric skull base.
4. Present a few cases of pediatric skull base
fractures and discuss their associated complications.
5. Review frequently associated complications
associated with specific skull base fracture locations.
Overview
Skull base:
• Comprised of 7 bones:
* paired frontal
* paired temporal
* unpaired ethmoid
* unpaired sphenoid
* unpaired occipital
• 3 divisions: anterior, central,
and posterior form the floor
of the anterior, middle, and
posterior cranial fossae.
From: Baugnon, KL et al.
Neuroimag Clin N Am 24 (2014)
439–465.
Review of the Atraumatic
Skull Base
Anterior Skull Base - Axial
Mildly Adapted From the Textbook: Diagnostic and Surgical Imaging Anatomy
of the Brain. Head & Neck. Spine.
Anterior Skull Base -Sagittal
From Textbook: Diagnostic and Surgical Imaging Anatomy
of the Brain. Head & Neck. Spine.
Age Related Anterior Skull Base Ossification
Birth: Nonossified.
2 years: only 4% have a fully ossified anterior
skull base.
4/+ years: fully ossified anterior skull base.
> 4 years: the foramen cecum is the only
nonossified portion.
Adapted from: Koch BL. Neuroimag Clin N Am 2014;24:513–529.
Coronal Progression of Anterior Skull Base Ossification
1 week old Coronal CT through the anterior skull
base:
Most of the anterior skull base including crista galli,
cribriform plate and perpendicular plate of ethmoid
bone are unossified. There is a large gap between the
orbital plates of frontal bones. Ethmoid air cells are
not yet developed.
2 year old coronal CT through anterior skull base:
Ethmoid bone is now mostly ossified, particularly
crista galli & cribriform plate. Note the normal
unossified gaps in the anterior cribriform plate.
18 Year old coronal CT through anterior skull base
which is completely ossified. Ethmoid air cells extend
superolateral to plane of the cribriform plate. The
fovea ethmoidalis is connected to the cribriform
plate by the lateral lamella.
Axial Progression of Anterior Skull Base Ossification
Normal Lucencies & Foramina of the anterior skull base
Foramina of the
Anterior Skull Base
Optic Nerve Canal
Superior Orbital
Fissure
Contents
Cranial Nerve II,
Ophthalmic artery,
and sympathetic
nerve fibers.
Cranial Nerves III, IV,
V1, VI and the
Superior Ophthalmic
vein
Central Skull Base
Mildly Adapted From the Textbook: Diagnostic and Surgical Imaging Anatomy
of the Brain. Head & Neck. Spine.
Central Skull Base Foramina & Contents
Foramina of the central
skull Base
Contents
Foramen rotundum
Cranial Nerve V2
Foramen ovale
Cranial Nerve V3
Carotid canal
Internal Carotid artery and
Sympathetic plexus
Foramen spinosum
Middle Meningeal artery
Vidian canal
Vidian nerve and artery
Foramen lacerum
Cartilage
Diagram of Central & Posterior Skull Base
Ossification Centers
*Indicates olivary eminence
From: Nemzek WR et al. AJNR Am J Neuroradiol 2000;21:1699-1706.
Normal Neonatal Central Skull Base
Lucencies & Ossification Centers on the Axial
Projection
Axial CT image of the central
skull base in a 1 week old:
Olivary eminence ( ), also
called the anterior foramen is a
triangular shaped lucency seen
only in the early newborn period;
This is located posterior to the
presphenoid ( ) and anterior to
the paired postsphenoid
ossification centers ( ). Note
the posterior and centrally located
posterior foramen ( )also
called the craniopharyngeal canal.
Progression of Skull Base Ossification
Black arrow ( )shows normal sequence of skull base ossification in a
posterior to anterior direction.
From: Nemzek et al. AJNR Am J Neuroradiol 2000;21:1699-1706.
Maturation of the Central Skull Base - Sagittal
Midline central skull base in a 1 week old:
A patent spheno-occipital synchondrosis ( ) and a
partially patent craniopharyngeal canal (
) are noted.
Midline central skull base in a 2 year old:
Spheno-occipital synchondrosis ( ) is patent and its
comprising bones are more uniform in density . A thin
sclerotic line persists at expected site of the
craniopharyngeal canal ( ). Note the ossifying
cribriform plate and small ethmoid and sphenoid sinuses
Midline central skull base in an 18 year old:
The spheno-occipital synchondrosis ( ) is completely
fused. Note the completely ossified cribriform plate and
mature ethmoid and sphenoid sinuses.
Synchondroses & Sutures of the Central Skull Base
Name
Spheno-occipital
synchondrosis
Craniopharyngeal
canal
(Posterior Foramen)
Olivary eminence
Canalis basilaris
medianus
Location
Pertinent Information
Located between and
separates the postsphenoid
ossification center from the
basiocciput
Where maximal skull base growth occurs. Remains
patent until teenage years. Small ossified bodies
can be seen at the synchondrosis during closure.
After complete closure, small divots, clefts, or
fissures on one or both sides of this synchondrosis
are often seen.
Extends from the floor of the
sella turcica to the roof of the
nasopharynx
Seen a partially patent canal in a only small
percentage of infants, with usual closure in early
infancy. Rarely, is pathologically widened from a
cephalocele containing the ectopic pituitary.
Triangular shaped,
cartilaginous lucency seen in
early newborn period between
presphenoid and the paired
postsphenoid bodies
Seen only in early newborn period. Rarely visible as
a sclerotic remnant in a small percentage of
children over 9 months of age.
Midline lucency in the
basiocciput posterior to the
spheno-occipital
synchondrosis
Very rarely seen as incidental finding that may be
associated with nasopharyngeal cysts. Variable in
shape and patency ( can be complete /incomplete).
Posterior Skull
Base
Both images are from Textbook:
Diagnostic and Surgical Imaging
Anatomy of the Brain. Head & Neck.
Spine.
Posterior Skull Base Foramina & Contents
Foramina of the Posterior
skull Base
Contents
Internal Auditory Canal
Cranial nerves VII & VIII and
labyrinthine artery
Cranial nerve VII &
stylomastoid artery
Cranial nerves IX, X, & XI,
internal jugular vein, inferior
petrosal vein & sigmoid sinus
Cranial nerve XII
Stylomastoid Foramen
Jugular Foramen
Hypoglossal Canal
Foramen Magnum
Medulla oblongata, ascending
spinal fibers of cranial nerve
XI, vertebral arteries, and
anterior & posterior spinal
arteries
Posterior Skull Base Ossification
Mastoid and
Petrous Temporal
bone segments
Cartilaginous & Membranous Components of the
Skeletally Immature Occipital Bone
Note: (
) refers to mendosal suture.
Skull Base Trauma
2 year old s/p MVA with magnified coronal (above)
and axial ( left) images through the right temporal
bone:
Blue arrow: right temporal bone fracture.
Yellow arrow: resultant disruption of right middle ear
ossicles and loss of normal ice cream cone configuration of the
incudomalleal joint.
2 year old who was backed over by a car:
White arrow: vertical fracture through sphenoid
extending to the sella. This child manifested with
clinical signs of Diabetes insipidus within days of
this injury.
Yellow arrows: preclival soft tissue swelling.
Magnified image of the sphenoid bone in the
same patient:
White arrow: vertical fracture through sphenoid
extending to the sella. This child manifested with
clinical signs of Diabetes insipidus within days of this
injury.
Yellow arrows: preclival soft tissue swelling.
7 year old ejected
during MVA:
Far right sagittal CT
image demonstrates
abnormal widening of
the joint space
between the right
occipital condyle with
right superior C1 facet
(blue arrow) in this
patient with
atlantoccipital
dislocation.
7 year old ejected from car during MVA:
Blue arrow - marked thickening of preclival
soft tissues.
Yellow arrow - retroclival hematoma.
7 year old ejected
during MVA:
Coronal image
demonstrates
abnormal widening of
the joint space
between the occipital
condyle and the
superior C1 facet on
both sides (blue
arrows) in this patient
with atlantoccipital
dislocation.
8 year old with focal expansion of the skull .
Yellow arrows: Note the focal abnormal expansion of the right sigmoid fossa and this
abnormality was in the region of an old fracture. There is a post-traumatic dural tear with
leptomeningeal herniation at the fracture site resulting in progressive skull erosion at the
fracture site from continuous CSF pulsations.
8 year old s/p head injury with left
posterior calvarial fracture and resultant
post traumatic thrombosis of left
transverse sinus:
White arrows: obliquely oriented fracture
through left occipital bone extending across
left lambdoid suture into petrous segment of
left temporal bone.
Yellow arrow: intracranial air adjacent to left
sigmoid sinus.
Blue arrows: abnormal isointense T2 signal
( thrombus) replacing normal dark flow void of
the left transverse sinus.
Orange arrows: left transverse sinus is
absent on the MRV.
Common Complications Associated with Specific
Skull Base Fracture Locations
Fracture Location:
Common Complications:
Anterior Skull Base
Intraorbital Injury
Sinonasal CSF leak/meningoencephalocele
Central Skull Base
Internal carotid artery injury
Injury to Cranial Nerves II, III, IV, V, or VI
Horner Syndrome
Posterolateral Skull Base
(Nonsquamous Temporal Bone)
Internal carotid artery injury
Injury to Cranial Nerves VII or VIII
Mastoid CSF leak/meningoencephalocele
Injury to middle and inner ear structures
Central Posterior Skull Base
Major venous vessel injury
Vertebrobasilar arterial injury
Injury to Cranial Nerves IX, X, XI, or XII
Injury to craniocervical junction/upper cervical
spine
Adapted from: Baugnon, KL et al. Neuroimag Clin N Am 24 (2014) 439–465.
References:
1. Baugnon KL, Hudgins PA (2014) Skull Base Fractures and Their
Complications. Neuroimag Clin N Am 24:439-465.
2. Koch BL. Pediatric Considerations in Craniofacial Trauma (2014)
Neuroimag Clin N Am 24:513–529.
3. Nemzek WR, Brodie HA, Hecht ST , Chong BW, et al (2000) MR, CT,
and Plain Film Imaging of the Developing Skull Base in Fetal
Specimens AJNR Am J Neuroradiol 21:1699-1706.
4. Madeline LA, Elster AD (1995 ) Suture closure in the human
chondrocranium: CT assessment. Radiology 196: 747-756.
5. Harnsberger HR, Osborn AG, Macdonald A, Ross J (2006)
Diagnostic and Surgical Imaging Anatomy of the Brain. Head &
Neck. Spine. Amirsys Incorporated.