CSF rhinorrhea

CSF rhinorrhea refers to a symptom of cerebrospinal fluid (CSF) leakage extracranially into the paranasal sinuses, thence into the nasal cavity, and exiting via the anterior nares. It can occur whenever there is an osseous or dural defect of the skull base (cf. CSF otorrhea).

Pathology

Etiology
  • congenital
  • acquired
    • traumatic: closed head trauma with an anterior base of skull fracture is the most common cause of CSF rhinorrhea ; natural barriers between the anterior cranial fossa and paranasal sinuses can be disrupted, leading to rhinorrhea, depending on the severity of trauma
    • iatrogenic
      • multiple neurosurgical procedures involving the skull base, e.g. transsphenoidal pituitary surgeries 
      • complex operations at the skull base  
      • otolaryngology procedures such as septoplasty and endoscopic surgery 
    • non-traumatic
      • spontaneous: chronic elevated intracranial pressure (pseudotumor cerebri) with medial sphenoid meningocele formation
      • tumors: malignant nasopharyngeal and skull base tumors invading or involving the skull base can cause CSF rhinorrhea
Anatomical locations
  • cribriform plate: it is the most common site for spontaneous CSF rhinorrhea
  • sphenoid: occur at the perisellar region and the lateral recess of the sphenoid sinus 
  • temporal bone and middle ear: common sites are the tegmen tympani and tegmen mastoideum

Radiographic features

CT
  • large osseous defects can be visualized on plain CT
  • CT cisternography is the diagnostic modality for diagnosing an occult site of CSF leak. It is performed after injecting contrast into the theca; however, this procedure is highly dependent on patient positioning and timing
MRI
  • 3D high-resolution T2W and T1W sequences are useful in diagnosing this condition
  • coronal reformations can depict the osseous defects with a greater degree of accuracy
Nuclear medicine
  • radionuclide studies have higher sensitivity in diagnosing leaks but have poor anatomic resolution

History and etymology

Leakage of spinal fluid into either the nose or the ear was first described as a pathologic entity in 1899 by Sir St Clair Thomson .

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