<prompt> Halo sign and handkerchief test are positive in-CSF RhinorrhoeaDeviated nasal septumNasal MyiasisChoanal atresia  <response>: Ans. is a i.e., CSF Rhinorrhoea Detection of CSF Leak in CSF Rhinorrhoea1 Biochemical testso Concentrations of Glucose are higher in CSF than in nasal discharge. Glucose value 30-40 mg protein value 100 mg max 200 mg support a diagnosis of CSF leako Presence of b2 transferrin is the most definitive test for detection of CSF and b2 transferrin assay is the test of choice when a confirmatory test is needed, because of high sensitivity as well as specificity.o b-trace protein prostaglandin D synthase is also used, however it is nonspecific as it is also present in human testes, heart and seroma.2 Basic clinical testso Tissue test Handker chief test:- Unlike nasal mucous, CSF does not cause a tissue to stiffeno Filter paper test:- Sample of nasal discharge on a filter paper exhibits a light CSF border and a dark central area of blood, i.e., double ring sign or halo sign.o Queckensted test:- Compression of the jugular vein leas to increased CSF leak due to increase in ICPo Rhinoscopy:- Visualization of CSF leak from paranasal sinus.3 CSF tracerso Intrathecal fluorescein dye adminstration, radionuclide cisternography, CT cisternography. 