CSF otorrhea

CSF otorrhea is defined as leakage of cerebrospinal fluid (CSF) from the subarachnoid space into the middle ear cavity or mastoid air cells and then out the ear via a perforation in the tympanic membrane or defect in the external ear.

Epidemiology

There are a number of underlying causes, and thus no specific demographic is affected.

Clinical presentation

Patients typically present with conductive deafness and a watery discharge from the ear (requiring a defect in the tympanic membrane).

The diagnosis can be confirmed by identifying beta-2 transferrin in the fluid.

Pathology

Etiology

• congenital
  • labyrinthine malformation (e.g., cochlear incomplete partition with stapes footplate deformity)
  • bony and dural defects along the temporal bone surface (especially tegmen)
  • enlargement/abnormal development of bony canals
    • facial canal 
    • subarcuate (petromastoid) canal 
    • Hyrtl fissure 
  • aberrantly distributed arachnoid granulations
• traumatic/iatrogenic
  • most often due to transverse fractures of the temporal bone
  • otologic surgery
• infection
• neoplastic

Radiographic features

CT cisternography

Findings on CT cisternography include:

• soft tissue mass with adjacent bony defect
• leakage of contrast into middle ear cavity
• bony defects
• labyrinthine malformations
• fistulous tracts 
• enlarged labyrinthine facial nerve canal

MRI

Findings include:

• CSF signal intensity in the bony defects
• CSF signal intensity in middle ear cavity
• associated empty sella
• dural enhancement after gadolinium administration

Nuclear medicine

Radionuclide cisternography

In complex cases, nuclear cisternography may be performed.

See also

• CSF rhinorrhea, which can sometimes be due to leak of CSF into the middle ear, through the Eustachian tube, and out the nose