Base of skull fracture comes up a lot in the CICM Fellowship exam. Usually, the question will show you some racoon eyes or a bruised mastoid, and then ask what other problems might be associated with a base of skull fracture. Usually, it has been Battle's sign (named after Dr William Henry Battle, rather than any association with warfare) which apparently has a 100% positive predictive value for base of skull fracture.
Questions involving BOSF thus far:
- Question 30.1 from the second paper of 2011
- Question 14.3 from the second paper of 2010
- Question 12.3 from the second paper of 2009
- Question 2 from the second paper of 2008
Clinical features of a base of skull fracture:
- CSF otorrhoea
- Racoon eyes (adults call it "bilateral periorbital haematoma")
- CSF rhinorrhoea
- Cranial nerve abnormalities:
- CNI damage (loss of olfaction)
- CN II entrapment (visual field defects or blindness)
- CN VII palsy (facial paralysis)
- CN VIII palsy (deafness)
- Blephaerohaematoma (i.e. of the eyelid)
- Pneumoencephalus (more of a radiological finding)
- Bloody otorrhoea
- CSF otorrhoea
Complications of a base of skull fracture
- Carotid artery dissection
- Cavernous sinus thrombosis
- Pneumocephalus due to positive pressure ventilation
- Accidental cannulation of the cranial cavity with the nasogastric tube
- Carotido-cavernous fistula
- CSF fistula
- Pituitary injury (eg. Question 12.1 from the second paper of 2014)
Antibiotics in base of skull fracture
A 1998 meta-analysis had concluded that "antibiotic prophylaxis after basilar skull fractures does not appear to decrease the risk of meningitis." This conclusion was supported by a 2011 Cochrane review. Nobody does this any more, and the college probably won't ask about it again.
Management of a CSF leak
- Even if your CSF is leaking, antibiotics do not seem to decrease the risk of meningitis.
- The CSF snot can be tested for β-2 transferrin to confirm that it is in fact CSF
- The leak should stop within 7 days.
- If it does not, one may wish to insert a lumbar drain (if this is feasible). The drain will allow CSF egress by another route, and therefore hopefully the CSF fistula will experience a lower pressure gradient, allowing it to heal.
- Surgical management (by some sort of patch with an intra and extradural repair) is the gold standard for refractory cases (Scholsem et al, 2008)