Clinical features may suggest a basal skull fracture even in the absence of a positive skull x-ray.

Evidence of anterior fossa fracture:

• CSF rhinorrhoea:
• due to damage to the cribriform plate
• this often requires formal dural repair

• bilateral periorbital haematoma:
• bruising limited to the orbital margins indicates blood tracking from behind

• subconjunctival haemorrhage where the posterior margin cannot be seen

Evidence of petrous temporal fracture:

• bleeding from the external auditory meatus

• CSF otorrhoea:
• through a torn tympanic membrane
• usually a linear injury which does not require formal dural repair

• Battle's sign:
• bruising over the mastoid
• may take 24-48 hr to develop

A basal skull fracture provides a route for infection. Antibiotics are given to prevent meningitis; the course lasts at least seven days, or if there is a CSF leak, until seven days after this has ceased.