Describe in brief recent techniques to localize the site of CSF leak.

• 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/

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.