Fracture of the base of the skull

A skull base fracture involves a fracture of the bones that form the basis of its outer surface (basis cranii externa), as well as structures of the inner surface of the skull base (basis cranii interna). [1]

According to ICD-10, a fracture of the base of the skull has the code S02.1 and includes fractures: the temporal, sphenoid and occipital bones; formed by parts of various bones of the cranial fossa, the upper wall of the orbit (orbital plate of the frontal bone); sinuses (sinuses) of the ethmoid and frontal bones. [2]

Epidemiology

According to statistics, in cases of severe craniocerebral trauma, the incidence of skull base fractures ranges from 3.5-24%, and they account for about 20% of skull fractures. 70% of fractures occur in the anterior cranial fossa and 20% in the middle.

According to some reports, the incidence of fractures of the base of the skull in children after head injuries is 11%. [3]

With isolated damage to the structures of the outer and / or inner surface of the base of the skull, the lethality reaches 29%; post-traumatic disability of varying degrees is observed in 55-60% of patients. Simultaneous fracture of the bones of the vault and the base of the skull in almost 45% of cases leads to the death of the injured. [4]

Causes of the skull base fracture

The causes of fractures of the base of the skull, as well as risk factors for violation of the integrity of the bone structures of its outer or inner surfaces, are significant  craniocerebral  and head / neck injuries. They can be obtained by drivers, passengers and pedestrians in an accident; in accidents at work and in many sports (primarily related to speed and extreme loads), as well as as a result of falls, severe bruises and direct blows to the head.[5]

A fracture of the base of the skull in infants is also etiologically associated with a head injury during falls, and in a newborn, such a fracture can be caused by an injury to the skull during childbirth (with incorrect removal of the head).

As evidenced by clinical experience, especially often these fractures affect the stony part (pyramid), the crest and processes (styloid and mastoid) of the temporal bone; cranial fossa; areas of the sphenoid sinus  , foramen magnum and occipital condyles. Such fractures can be isolated, but often with TBI, the cranial vault also suffers, that is, a fracture of the bones of the vault and base of the skull is combined. See -  The structure of the skull [6]

Almost 10% of fractures of the base of the skull (in particular, the occipital condyle) are associated with a fracture of the cervical spine (two upper vertebrae of the craniovertebral zone).

Distinguish between a closed fracture of the base of the skull with a closed head injury, when the skin covering the area of the fracture is not damaged, as well as an open fracture of the base of the skull - with an open head injury with skin rupture and bone exposure.

A fracture of the bones of the base of the skull can be comminuted - if the bone is crushed into separate fragments, and when the broken segments are displaced inward (towards the meninges and the brain), the fracture is called depressed. A bone fracture that does not shift is defined as a linear fracture of the base of the skull.

A fracture of the skull with transitions to the base is noted when the crack of the cranial vault continues on the bones of its base.

A fracture of the base of the skull of the temporal bone often occurs, since its lower part enters the base of the skull, the scaly part is the lateral wall of the cranial vault, and the anterior and posterior surfaces (together with parts of other bones) form the middle and posterior cranial fossa of the inner base of the skull. In addition, the  temporal bone  belongs to the airways, it is thinner than other bones of the skull (frontal - 1.4 times, and the occipital - 1.8 times), has two processes (styloid and mastoid), and is also penetrated by several canals, tubules, furrows and crevices. Read more -  Temporal bone fracture  [7] 

 

Pathogenesis

As you know, the pathogenesis of any bone fractures is due to a significant mechanical (high-energy) effect, in which the bone is deformed and destroyed due to exceeding the limit of the biomechanical properties of bone tissue (having a layered crystalline lamellar structure) - resistance to applied force (elasticity) and strength.

More information in the material -  The structure and chemical composition of bones

Symptoms of the skull base fracture

The first signs of a fracture of the base of the skull are due to its localization and the nature of damage to the bone structures. But, in any case, the victim feels severe pain, dizziness and loses consciousness; there may be vomiting, instability of blood pressure and heart rate (tachy- or bradycardia) is noted.

If the fracture affects the petrosal part (pars petrosa) of the temporal bone, blood accumulates in the tympanic cavity of the ears (hemotympanum) and bleeding from the external auditory canals is possible.

With the rupture of a part of the lining of the brain with fractures of the base of the skull, the outflow of cerebrospinal fluid from the nose or ears is associated -  liquorrhea , which in most cases is observed several hours after the injury. [8]

In addition, the characteristic symptoms of such a fracture include retroauricular ecchymosis - intradermal hemorrhage behind the ears - in the mastoid process of the temporal bone (a symptom or sign of Battle), and around the eyes - periorbital ecchymosis (called "raccoon's eye"). Ecchymosis in the behind-the-ear region and otolikvorrhea (leakage of cerebrospinal fluid from the ears) are observed with a fracture of the middle cranial fossa (fossa cranii media), that is, the parts of the sphenoid and temporal bones forming it, and its other manifestations are loss of sensitivity of the middle part of the face, violation of the gag reflex, tinnitus and conductive deafness.

In patients with a fracture localized in the area of the posterior cranial fossa (fossa cranii posterior) and located in the occipital bone of the foramen occipitale magnum, vomiting, nasal liquorrhea and bleeding from the nose and ears, Buttle's sign and ecchymosis of the periorbital region are observed.

Hemorrhages in the eye area may indicate a fracture of the bones of the inner surface of the base of the skull, forming the anterior cranial fossa (fossa cranii anterior), in which anosmia (loss of smell), epistaxis, hemorrhage under the conjunctiva and corneal edema, pronounced ophthalmoplegia  (impaired eye movement ) are also noted  ) and drooping of the upper eyelid -  ptosis . [9]

Complications and consequences

With fractures of the base of the skull (isolated or with a fracture of the bones of the vault), serious complications can occur and consequences can develop that can be irreversible.

A fracture of the base of the skull can be complicated by meningitis due to the increased likelihood of bacteria entering from the paranasal sinuses, nasopharynx and ear canal (since the fracture in many cases affects the pyramid of the temporal bone, the tympanic membrane and the auditory canal).

Quite often, there is a violation of the integrity of the internal carotid artery in the cavernous (cavernous) part of this vessel with the formation of an arteriovenous fistula - a direct carotid-cavernous fistula   between the artery and the cavernous sinus of the dura mater.

The consequences include:

• pneumocephalus (intracranial accumulation of air);
• cerebral edema  with the development of intracranial hypertension;
• compression of the brain  with bone fragments or  subdural hematoma  (resulting from subarachnoid bleeding);
• dissection, pseudoaneurysm, or thrombosis of the carotid artery;
• damage to the  cranial nerves  (oculomotor, facial, vestibular cochlear), leading to neurological manifestations in the form of paresis and paralysis;
• cerebral coma .

Diagnostics of the skull base fracture

The diagnosis of a fracture of the bones of the base and calvarium is mainly clinical and is carried out according to the same algorithm as the  diagnosis of traumatic brain injury , with a mandatory assessment of the severity of the injury.

Blood tests are required (general, for the level of electrolytes and oxygenation), as well as the  analysis of cerebrospinal fluid  and its bacteriological culture - for antibiotic therapy.

Instrumental diagnostics consists of X-rays of the skull and cervical spine, CT of the skull,  magnetic resonance imaging (MRI) of the brain , and  electroencephalography .

Differential diagnosis

In newborns, differential diagnosis is carried out with congenital underdevelopment of the bones of the skull, intracranial hemorrhage (which may occur due to birth trauma), as well as  encephalocele , which may be accompanied by liquorrhea. 

Treatment of the skull base fracture

How first aid (first aid) is carried out, which is provided at the site of injury before the arrival of the medical team, and what needs to be done, in detail in the publication -  Help with traumatic brain injury e [10]

After hospitalization of the victims, treatment is carried out in the intensive care unit and consists of anti-shock measures, cessation of bleeding, support of respiratory function, stabilization of blood pressure and heart rate (with the use of appropriate medications). [11]

To relieve cerebral edema, dehydration is performed with diuretic injections. To prevent the development of meningitis when an infection enters the lining of the brain, antibacterial drugs are used preventively (although the effectiveness of using antibiotics for prevention has long been questioned). Read also -  Treatment of traumatic brain injury

In case of persistent liquorrhea, as well as in cases complicated by vascular damage and intracranial bleeding, pressing of broken segments into the skull, compression of the brain, significant damage to the cranial nerves, surgical treatment is necessary - neurosurgical intervention with craniotomy. [12]

How long does it take for a skull base fracture to heal? The healing process can take several months (a linear fracture heals much faster). At the same time, the rate of reparative regeneration, due to which bone fractures heal, may depend on the individual characteristics of patients and their increase. This refers to bone metabolism, the regenerative activity of osteoblasts in the cambial layer of the periosteum, as well as the rate of destruction of bone tissue by osteoclasts. [13]

Rehabilitation after a fracture of the base of the skull, as well as  rehabilitation after a traumatic brain injury , is carried out according to an individual plan - depending on the nature of neurological, ophthalmological and other disorders that each patient has. To restore the lost function and improve the condition, physiotherapy, physiotherapy exercises, massage, speech therapy, etc. Are used. [14]

Prevention

A fracture of the base of the skull can only be prevented by the prevention of craniocerebral injuries in all road users, during sports, in the industrial sphere and in everyday life.

Forecast

For patients with skull base fractures, the prognosis depends on whether the fracture is displaced. With isolated fractures without displacement, the outcome is successful. Overall, however, most patients with these fractures remain functional or neurological. 

Most CSF leaks resolve spontaneously within 5-10 days, but some may persist for months. Meningitis may occur in less than 5% of patients, but the risk increases with the duration of CSF leak. Conductive hearing loss usually resolves within 7 to 21 days. [15], [16]

After a fracture of the base of the skull (taking into account its severity), the survival rate is 48-71%, after a fracture of the bones of the vault and base of the skull - no more than 55%.