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# Basilar skull fracture

A break in the bones at the [base of the skull](https://durgical.com/en/anatomy/occipital-bone/). Bruises behind the ear or around the eyes and clear fluid from the nose or ear are the clues.

Updated 2026-11-01

## Structures involved

Tap one to see what it is and open it in 3D.

- [Temporal bones](https://durgical.com/en/anatomy/temporal-bone/)
- [Base of the skull](https://durgical.com/en/anatomy/occipital-bone/)
- [Sphenoid bone](https://durgical.com/en/anatomy/sphenoid-bone/)
- [Cribriform plate](https://durgical.com/en/anatomy/cribriform-plate/)
- [Ethmoid bone](https://durgical.com/en/anatomy/ethmoid-bone/)
- [Dura mater](https://durgical.com/en/anatomy/cranial-dura/)
- [Eardrum](https://durgical.com/en/anatomy/tympanic-membrane/)
- [Facial nerve (VII)](https://durgical.com/en/anatomy/facial-nerve/)
- [Vestibulocochlear nerve (VIII)](https://durgical.com/en/anatomy/vestibulocochlear-nerve/)
- [Olfactory nerve (I)](https://durgical.com/en/anatomy/olfactory-nerve/)
- [Nasal cavity](https://durgical.com/en/anatomy/nasal-cavity/)
- [Sphenoid sinus](https://durgical.com/en/anatomy/sinus-of-sphenoid-bone/)

## Why it happens

- [CSF and the blood–brain barrier](https://durgical.com/en/physiology/csf-and-the-blood-brain-barrier/)
- [Gray and white matter, cerebellar cortex, meninges](https://durgical.com/en/histology/gray-and-white-matter-cerebellar-cortex-meninges/)

## What it is

A fracture of the skull base, involving the [temporal bone](https://durgical.com/en/anatomy/temporal-bone/) (petrous part), the occipital bone, the sphenoid or the [cribriform plate](https://durgical.com/en/anatomy/cribriform-plate/) of the ethmoid. It may tear the dura and open a route between the brain's fluid spaces and the nose, sinuses or middle ear, and can injure the cranial nerves that cross the skull base.

## Who gets it

It appears in a notable share of moderate and severe head injuries. In Colombia, motorcycle crashes, falls and assaults are the main mechanisms of traumatic brain injury and therefore of skull base fractures.

## Causes

- Motorcycle and car crashes
- Falls, especially from height
- Assaults and blows to the head
- Sports and work accidents

## Risk factors

- High-energy head trauma
- No helmet on motorcycles or bicycles
- Alcohol intoxication
- Older age (falls)

## Pathophysiology

Force transmitted through the skull concentrates at the thin, irregular bones of the base. Fractures through the anterior fossa tear the dura over the cribriform plate and cause CSF rhinorrhoea and periorbital bruising; temporal bone fractures injure the middle ear, facial nerve and inner ear and cause otorrhoea and mastoid bruising. Blood tracks along fascial planes, so the bruising usually appears hours to a day or more after the injury.

## Classification

- Anterior cranial fossa (frontobasal) fractures
- Middle fossa and temporal bone fractures: longitudinal (more common, conductive hearing loss) and transverse (more facial nerve and sensorineural injury); also otic capsule sparing versus violating
- Posterior fossa (occipital condyle and clivus) fractures

## Symptoms and signs

- Periorbital bruising (raccoon eyes)
- Bruising over the mastoid process behind the ear (Battle sign), often delayed
- Clear or blood-tinged fluid from the nose (rhinorrhoea) or ear (otorrhoea)
- Blood behind the [eardrum](https://durgical.com/en/anatomy/tympanic-membrane/) (haemotympanum)
- Loss of smell, hearing loss, vertigo or facial weakness

## Red flags

- Falling level of consciousness or unequal pupils (intracranial haematoma)
- Fever, headache and neck stiffness (meningitis from a CSF leak)
- Persistent clear rhinorrhoea or otorrhoea
- Facial nerve palsy, especially of immediate onset
- Signs of carotid or [vertebral artery](https://durgical.com/en/anatomy/vertebral-artery/) injury (focal deficit, Horner syndrome)

## Diagnosis

**Clinical**
Clinical signs (raccoon eyes, Battle sign, haemotympanum, CSF leak) raise suspicion. Full neurological examination with Glasgow Coma Scale, cranial nerve testing including [facial nerve](https://durgical.com/en/anatomy/facial-nerve/), hearing and smell, and cervical [spine](https://durgical.com/en/anatomy/region/spine/) precautions.

**Tests**
Beta-2 transferrin (or beta-trace protein) in nasal or ear fluid confirms CSF. The halo (ring) sign on gauze is a quick but non-specific bedside clue.

**Imaging**
Thin-slice non-contrast CT of the head and skull base (bone windows) is the test of choice. CT angiography when the fracture crosses the [carotid canal](https://durgical.com/en/anatomy/carotid-canal/) or a vascular injury is suspected. CT or MRI cisternography to localise persistent leaks.

## Differential diagnosis

- Periorbital bruising from direct facial trauma or orbital fracture
- Allergic or vasomotor rhinitis (clear nasal discharge)
- Middle ear haemorrhage from direct ear trauma
- Facial fractures (Le Fort, nasoethmoidal)

## Goal of treatment

Find and treat associated brain injury, protect against meningitis, let the CSF leak close, and preserve cranial nerve function.

## Treatment

**Acute**
ATLS care with airway protection and cervical spine precautions; avoid nasal tubes (nasogastric tube, nasotracheal intubation, nasal suctioning) when an anterior skull base fracture is suspected; use the oral route instead.

**Conservative**
Most CSF leaks close on their own within days: head-of-bed elevation, avoiding nose blowing and straining, sneezing with the mouth open, and treating constipation and cough.

**Medical**
Routine prophylactic antibiotics are not supported by current evidence; meningitis is treated promptly with antibiotics if it occurs. Corticosteroids may be used for delayed or partial facial palsy.

**Procedure**
Lumbar drain for leaks that persist despite conservative care.

**Surgical**
Surgical repair of a persistent CSF leak (often endoscopic endonasal), facial nerve decompression for immediate complete palsy, and evacuation of associated haematomas.

**Follow-up**
Nursing priorities: neurological checks and GCS, monitoring for fluid from the nose or ear (collect it, do not pack the nose or ear), temperature and signs of meningitis, and patient teaching to avoid nose blowing.

## Complications

- Persistent CSF leak
- Bacterial meningitis
- Facial nerve palsy
- Conductive or sensorineural hearing loss and vertigo
- Anosmia (loss of smell)
- Carotid artery injury and [cavernous sinus](https://durgical.com/en/anatomy/cavernous-sinus/) fistula

## Prognosis

Outcome depends mostly on the associated brain injury. Most CSF leaks stop within a week, and delayed facial palsy usually recovers; immediate complete palsy and sensorineural hearing loss have a worse outlook.

## Prevention

- Helmet use on motorcycles and bicycles
- Seatbelt use
- Fall prevention in older adults and at work

## Test yourself

Think of the answer, then tap the question to see it.

## Which signs suggest a basilar skull fracture?

Raccoon eyes, Battle sign (mastoid bruising), haemotympanum, and CSF rhinorrhoea or otorrhoea.

## Why should a nasogastric tube be avoided in suspected anterior skull base fracture?

It can pass through the fractured cribriform plate into the cranial cavity; an orogastric tube is used instead.

## Which test confirms that nasal or ear fluid is CSF?

Beta-2 transferrin (or beta-trace protein) in the fluid.

## Are prophylactic antibiotics recommended for basilar skull fracture with CSF leak?

No. Current evidence does not support routine prophylactic antibiotics; patients are watched for meningitis.

## Which cranial nerve is most at risk in a transverse temporal bone fracture?

The facial nerve (VII), along with the vestibulocochlear nerve (VIII).

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## Related conditions

- [Traumatic brain injury](https://durgical.com/en/conditions/traumatic-brain-injury/)
- [Epidural haematoma](https://durgical.com/en/conditions/epidural-haematoma/)
- [Subdural haematoma](https://durgical.com/en/conditions/subdural-haematoma/)
- [Bacterial meningitis](https://durgical.com/en/conditions/bacterial-meningitis/)
- [Bell palsy](https://durgical.com/en/conditions/bell-palsy/)
- [Hearing loss (conductive and sensorineural, including sudden hearing loss)](https://durgical.com/en/conditions/hearing-loss/)
- [Major trauma (polytrauma): ATLS primary survey](https://durgical.com/en/conditions/major-trauma-atls-primary-survey/)
- [Orbital floor (blowout) fracture](https://durgical.com/en/conditions/orbital-floor-fracture/)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Skull fracture](https://medlineplus.gov/ency/article/000060.htm) (MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine), 2024); [Antibiotic prophylaxis for preventing meningitis in patients with basilar skull fractures](https://pubmed.ncbi.nlm.nih.gov/25918919/) (Cochrane Database of Systematic Reviews (PubMed), 2015).

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Source: https://durgical.com/en/conditions/basilar-skull-fracture/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/basilar-skull-fracture/