Skull fractures, that are
fractures of the cranial vault and base of skull, excluding facial
fractures, are the results of significant force to the head and are
classified according to the integrity of the overlying skin, the site, the
shape of the fracture and the final position of the bony fragments. As a
result of the force applied there is often associated brain injury.
Skull fractures in all but
the neonate are caused by significant impact force to the cranium and may
be associated with a variety of other injuries, both intracranial and
extracranial. The cranial vault develops form membranous bone, with
ossification of the bones commencing at six weeks gestation and the
syndesmotic sutures fusing by the fifth decade. Growth of the skull vault
is driven by the growth of the underlying brain, with maximum rate of
growth in the first twelve months during which time the brain doubles its
weight. Growth of the skull is complete by ten to twelve years. This
development of the skull is important as different types of fractures
occur in the different age groups.
Simple linear fractures
constitutes about 50% of all, and the compound fractures about 25%. Simple
depressed fractures make up about 6 %.
Mechanisms of injury:
The biomechanics of skull
fractures depend on a direct force being applied to the skull,
surface area of the force,
of the force,
point impact, and the age of the
If the force is applied over
a longer time it will result in acceleration of the head. Bone in the
adult and older child, has great resistance to compression but little
resistance to tensile strain, and thus when direct force is applied to the
skull, the skull is deformed instantaneously with the weaker tensile
strength resulting in the inner table fracturing initially and if
the force is of sufficient strength then the outer table will also
fracture. These findings are not true for young children where the
bone still has elastic properties and can therefore be deformed without
fracturing. The propagation of the fracture depends on the force
applied and the local anatomy, namely, the thickness of the bone and the
presence of bony ridges.
Sutural diastasis can
occur in young patients without significant force, but in the adult
patient with fused sutures it is a sign of significant trauma and may well
be associated with intracranial complications.
Remote effects of
forces applied to the skull can result in fractures at a site distant to
that of the impact, due to the transmission of energy through the facial
bones or with the development of a release fracture. With the application
of a force to the skull, the shortening of a skull diameter in line with
the force of lengthening of the diameter at right angles to the force
causes a reversal of the energy forms, with the compressive strain on the
inner table and the tensile strain on the outer table.
Simple linear fractures may
only present with a boggy scalp swelling, with a range of neurological
signs and varying levels of consciousness. Compound fractures may well
have associated evidence of a dural laceration with CSF leak or brain
herniating through the wound.
Skull X-rays have been the
standard radiological investigation in head injuries, and still have
their place, even with the introduction of CT scans. The advantages of
skull x-rays are, the majority of linear fractures are revealed,
air fluid levels are well shown within the para-nasal sinuses and
junction is well delineated on skull x-rays, the majority of adult
patients have a calcified pineal gland and therefore in departments
with no access to CT scans, a skull x-ray may reveal midline shift due
to a mass lesion, management plans can be made on the result of a
skull x-ray. The
diagnosis of a base of
skull fracture remains clinical and may not be shown on skull x-rays
but the associated radiological signs of pneumocephaly and air-fluid
level in the frontal or sphenoid sinuses suggest the presence of such
Patients who require a CT
scan do not require a skull x-ray.
CT Scanning has
revolutionized the management of trauma, in particularly head injuries,
with good resolution of the cranial vault on axial bone windows’ and the
intracranial contents on ‘soft tissue windows’, but there are limitations
with imaging the posterior fossa and for base of skull imaging coronal
scans must be done. Two dimensional CT scanning in trauma patients is
sufficient in the radiological assessment of skull fractures, with no
further information gained from three dimensional scanning.
imaging is not superior to CT scanning in the acute assessment of head
injured patients, due to the length of time taken for each scan, the use
of non ferro-magnetic anesthetic equipment and the poor resolution of the
Fractures of the cranial
vault and base of skull are the results of significant force to the head
and are classified according to the integrity of the overlying skin, the
site, the shape of the fracture and the final position of the bony
fragments. As a result of the force applied there is often associated
brain injury. The classification is important as it highlights the
various complications, as well as the different approaches to their
There are many systems to
classify skull fractures, as listed below; however the most practical
system is a combination of all three:
or displaced (slot, comminuted, depressed or elevated) skull fractures.
Simple or compound
(related externally to the integrity of the overlying scalp and/or
internally involving the paranasal air sinuses, or mastoid air cells)
Anatomically, base of
skull or vault fractures.
These fractures are
significant if the fracture line crosses a meningeal artery or one of
its branches (may lead to extradural hemorrhage), a dural venous sinus
(may result in venous thrombosis, headache, and seizures), and extends
into the paranasal sinuses. In the base it usually skirts the foramina
because of the strong buttresses of bone around the foramina.
carries the risk of infection and cortical thrombophlebitis and
require thorough debridement and prophylactic antibiotics.
In children, these
fractures are often widely separated (usually lambdoid sutural
diastasis) and usually heal by union within few months unlike in
Growing fracture (Cranio-cerebral erosion):
Linear fracture-CT scan
In children, some linear
fractures are associated with torn dura due to dense attachment of the
dura to the bone in this age group. A rare complication, which occurs in
0.6% of linear skull fractures in pediatric patients: 90% occur before the
age of three. The fracture is associated with a dural tear, preventing
primary dural healing and resulting in progressive enlargement and
eversion of the fracture line. The arachnoid sac may contain CSF and
herniated brain with or without porencephaly. The treatment for the two
forms is different, as the former requires a duro-cranioplasty (debridement
of the damaged brain and dural repair) whilst the latter a shunt, in
order to prevent progressive neurological deterioration.
fracture are more common in children. Birth injuries, and fall from a
height are the common causes. Any depression more than 5 mm is likely to
have injured the dura. In a pond fracture, the inner table and the
dura are intact.
Surgical elevation is
recommended by many. Others argue that the damage occurs at the time of
injury and elevation do not help. No reliable data is available to support
surgery except for cosmetic purposes. Elevation over a sinus area may be
|| Depressed fracture-3D
|| Pond fracture
fracture is an emergency to prevent infective sequelae.
Surgery for these patients is
initial local wound closure after thorough cleaning and removal of
foreign bodies, to achieve hemostasis and prevent infection. If there is
no dural laceration this will be the definitive treatment.
Definitive surgery must be
performed as soon as possible, if there is a suspected dural laceration or
intracranial hematoma or moderate to severe wound contamination. Dural
laceration should be suspected if there is CSF in the wound, brain
herniation, pneumocephaly in the absence of a base of skull fracture or on
imaging there is intracranial air, the outer table of the skull is
depressed below the inner table
(or any depression above 5 mm), or a
spicule of bone within the cranium
The surgical principles are:
cleaning of the wound with great attention to removal of all foreign
bodies and debridement of devitalized scalp.
of the bone around the fracture with a craniotomy or craniectomy to reveal
a margin of normal dura and then removing the depressed fragment without
causing further cortical laceration.
Define the dural edges and
extend the opening to inspect the underlying brain, evacuate intradural
hematoma, foreign bodies and achieve hemostasis.
closure, with primary suturing if there is no significant dural loss;
however if there is a large dural defect, a duraplasty must be performed,
using pericranium, fascia lata or an appropriate xenograft.
fragments can be replaced if the wound is thoroughly cleaned, there is no
clinical evidence of wound infection, the surgery is performed within 24
hours of injury and the patient is treated with the appropriate
depressed fractures with associated facial fractures should be treated
acutely as a combined procedure, as patients who have a high Glasgow Coma
Score, no evidence of raised ICP or displacement of midline structures, do
not appear to have an increase in operative morbidity . Earlier approaches
to the management were with two or three operations, the initial
neurosurgical procedure followed 7 to 10 days later by maxillo-facial
reconstruction; however acute surgery is possible with improvements in
neuroanesthesia, neurointensive care and the new plating sets for reducing
and fixing these fractures.
Scalp wound must be closed
primarily or if there is a large skin defect the scalp can be ‘expanded’
by making parallel release incisions in the galea parallel to the wound or
using a rotation flap to cover the fracture, with skin grafting the donor
fractures are caused by tangential injuries which slice off a portion of
the scalp, skull and the underlying dura.
Slot fractures are
always contaminated and are due to penetrating trauma caused by a blade,
axe or machete, and therefore usually associated with a dural
laceration. Principles of treatment are the same as in compound depressed
The local anatomy of the
skull base, with the paranasal sinuses and mastoid air cells in
close proximity to the
dura, usually renders these fractures compound.
There has been no
adequate controlled study to assess the benefit of prophylactic
in the prevention of
post-traumatic meningitis in patients with base of skull fractures.
working party of the
British Society for Antimicrobial Chemotherapy recommends close
monitoring of patients to
diagnose meningitis early and treat appropriately.
Base of skull fractures
can be sub-divided anatomically into the fossae namely, anterior,
middle and posterior
Fossa Fractures may be
presumed with scalp emphysema,peri-
or raccoon eyes where there is subconjuntival hemorrhage with
epistaxis, anosmia, CSF rhinorrhoea,
or blindness, suggest an anterior
Epistaxis is usually
managed with adequate nasal packing.
The olfactory nerve
filaments are fine and delicate and can get injured in cribriform
plate fractures. Anosmia
may be missed in acute stages. An associated dural tear may result
in CSF rhinorrhoea; it
usually stops in 3-4 days. Persistent cases require a repair.
Optic foramen region fractures may
result in optic
nerve injuries and warrant immediate attention.
Pneumocephalus, due to
entry of air from the sinuses, is an emergency. The patient develops a
tension pneumocephalus due to a dural flap valve or with the use of
positive airway pressure
with an anaesthetic mask.
A twist drill to let out the air may be life saving.
Middle fossa fractures
often extend to anterior fossa and posteriorly to petrous pyramid.
Blood in the external
auditory meatus, deafness, facial palsy, or delayed appearance of
subgaleal altered blood over the mastoid ( Battle sign) may point to a
middle fossa fracture.
The fracture may also
injure the cavernous sinus, and may result in carotico-cavernous
Contrast cisternography-CSF leak
thru' ant cranial fossa fracture
cribriform plate with CSF rhinorrhoea
The 3rd, the 4th, and the 6th
nerves are at risk. The 3rd nerve paresis in patients with a normal level
of consciousness are due to traction injuries, however if a sign of
transtentorial herniation, the third nerve palsy will be preceded by a
decrease in the patient’s level of consciousness. The 4th nerve has the
long subarachnoid course and may sustain traction injury. The 5th nerve
lies in the lateral wall of the cavernous sinus with the three divisions
exiting through the middle fossa, where fractures can injury the nerve
directly. The 6th nerve is tethered by the posterior cerebral and
superior cerebellar arteries as it exits the brain stem and as it enters
the cavernous sinus through Dorello’s canal, therefore any shift in the
brain stem relative to the base of skull can cause traction on this nerve.
Longitudinal fracture due to
a lateral blow is common, and may result in facial nerve injury.
The less common transverse fracture as a result of occipital blows involve
the 7th and 8th nerves along with disruption of vestibular and cochlear
components of the labyrinth. The facial nerve is susceptible to injury
within the petrous bone from middle fossa fractures. Facial nerve palsy
immediately after the injury suggests traction, torsion or tearing of the
nerve, whilst those that are of delayed onset are due to nerve swelling or
a compressive haematoma in the facial canal and both groups of patients
may be treated conservatively as the recovery of facial nerve function is
91.7% in the former and 94.1% in the later.
Some surgeons recommend
large doses of steroids to prevent a delayed facial palsy. Surgical
decompression/ repair via transmastoid translabyrinthine approach is
being tried in facial nerve injuries with varying reports.
Deafness from a middle
fossa fracture, if associated with a facial palsy, suggests a neural
injury. If not, ossicular dislocation must be excluded as this is a
treatable form of deafness. Therefore all patients with a middle fossa
base of skull fracture must have full hearing assessment within two weeks
CSF otorrhoea is
rare and subsides spontaneously almost invariably.
(with an intact tympanic membrane) may require surgical intervention.
is rare complication, but should be suspected if the patient has
bilaterally dilated pupils and refractory hypertension. The majority
of these patients has a disrupted optic chiasm as well as disrupted
Post. fossa fractures
are rare. associated cervical spine injuries must be ruled out..
The 6th to12th nerves may be injured.
Skull fractures, per se may
be of no clinical significance, however when associated with decreased
level of consciousness, or a focal neurological deficit, it may be an
indicator of an intracranial hematoma or cortical contusion. A force
severe enough to fracture the skull may produce brain damage as well.
The risk of intracranial
hematomas in adults and pediatric patients with head injuries depends on
two important clinical findings, namely, a skull fracture and the
patient’s level of consciousness. The risks of intracranial hemorrhage (extradural,
subdural, intracerebral) following a skull fracture depend on the age and
the level of consciousness of the patient. 1 in 12 of
children and 1 in 4 of adults with decreased GCS and fracture, have an ICH.
Infection results from
delayed treatment or inadequate treatment of the compound fractures,
ranging from superficial wound infection to the more severe intracranial
complications of meningitis, subdural empyema or brain abscess.
Hence a skull fracture should
alert the neurosurgeon when patients, with a history of head injury,
present with a neurological problem.