- The clinical finding of CSF rhinorrhoea represents only the site of existing CSF but not the origin of the fistula.
- Accurate definition of the leakage site is undoubtedly the must important factor in successful treatment of the problem.
Imaging
- confirm the presence of the CF leak.
- Identify any underlying cause, anatomical abnormality.
- Determine the anatomical site,side and size of fistula.
- Assists in planning the surgical approach
- Look for : Bone defects
- Air fluid levels
- Erosions
Plain films:
- demonstrate pneumocephalus/air fluid levels/
[table id=35 /]
MRI:
- Not recommended as a 1st line imaging modality.
- Only when enephalocele is suspected.
- Doesn’t delineate bony defect/costly/time consuming.
CT cisternography:
- Better localization of the site of CSF leak.
- Intrathecal injection of contrast (metrizamide neurotoxicity. Next generation Iohexol).
- It may miss cribriform/ethmoid sinus defects
- invasive procedure
- ADR: N/V , headache, acute organic psychotic symptoms.
MR cysternography:
- Avoids exposure to ionization radiation.
- Avoids intrathecal infection of contrast(benefits)
- T2 weighted image detects the pressure of CSF in the sinonasal cavity and pulse sequence if performed enhances probability of detecting CSF .
- False negative result may be there.
