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:

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)

References

Pretto, Flores L., C. S. De Almeida, and L. A. Casulari. "Positive predictive values of selected clinical signs associated with skull base fractures." Journal of neurosurgical sciences 44.2 (2000): 77-82.

Tubbs, R. Shane, et al. "William Henry Battle and Battle's sign: mastoid ecchymosis as an indicator of basilar skull fracture: Historical vignette." Journal of neurosurgery 112.1 (2010): 186-188.

Katzen, J. Timothy, et al. "Craniofacial and skull base trauma." Journal of Trauma and Acute Care Surgery 54.5 (2003): 1026-1034.

Samii, Madjid, and Marcos Tatagiba. "Skull base trauma: diagnosis and management." Neurological research 24.2 (2002): 147-156.

Villalobos, Tibisay, et al. "Antibiotic prophylaxis after basilar skull fractures: a meta-analysis." Clinical infectious diseases 27.2 (1998): 364-365.

Ratilal, Bernardo O., et al. "Antibiotic prophylaxis for preventing meningitis in patients with basilar skull fractures." Cochrane Database Syst Rev 8 (2011).

Scholsem, Martin, et al. "Surgical management of anterior cranial base fractures with cerebrospinal fluid fistulae: a single‐institution experience." Neurosurgery 62.2 (2008): 463-471.