- After head trauma
- But most are spontaneous with out any history of trauma
- After nasal allergy is excluded, a CSF ( Cerebro Spinal Fluid) leak from the brain has to be ruled out ( CSF Rhinorrhoea)
- Handkerchief test : If the handkerchief gets stiff on drying then the discharge is nasal secretion. If the handkerchief remains limp on drying then the discharge could be CSF.
- Glucose test: Normally glucose is absent in nasal secretion. If on examining a sample of nasal secretion in the lab it is reported as positive for glucose, it could be CSF.
- CT/MRI Scan of the PNS