Base of skull fracture

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
• Haemotympanum
• 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

• Meningitis/encephalitis
• 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)