The leakage of cerebrospinal fluid (CSF) into nasal, oral or ear cavities and its subsequent drainage from these cavities may be caused by trauma, intracranial surgical procedures, infection, hydrocephalus, congenital malformations and neoplasms. The most severe consequence of a CSF leak is meningitis.

Epidemiology

• Prevalence - 70-80% are related to accidental trauma
  • 2-4% of head injuries result in CSF leaks

Etiology

• Trauma
• Nontraumatic
  • Surgery (usually spinal or neurosurgery)
    • Postoperative defect
    • Spontaneous leak
  • Infection
  • Tumor obstruction
  • Congenital defects (at the base of the skull)
  • Hydrocephalus

Pathophysiology

• Beta transferrin, a protein produced by neuraminidase activity in the brain, is uniquely found in CSF and perilymph fluid
• Interruption of anterior cranial fossa floor allows leaks through the cribriform plate

Clinical Presentation

• CSF leakage most commonly presents as otorrhea or rhinorrhea
• Patient may complain of salty or sweet taste
• Presence of halo sign on used tissues or bed linen

Diagnosis

• Laboratory testing
  • Chemical analysis (eg, Glucostix) of the fluid for glucose and protein is unreliable in determining the presence of CSF fluid
  • The presence of Beta-2 transferrin indicates CSF leakage (high specificity and sensitivity)
• Imaging studies
  • Radiographic studies, with or without intrathecal injection of dye or radioisotope, are not always successful in demonstrating small or delayed CSF leaks
  • High resolution CT is initial study of choice
  • MRI
  • Cisternogram by CT or MRI