ExplanationA. Handkerchief test: Mucus stiffens the handkerchief but CSF does not.
Halo sign/Target sign/Double ring sign: This test is useful when CSF rhinorrhoea is associated with epistaxis (in the immediate period after trauma). A drop is put on Whatman’s filter paper. The blood in the drop produces a central circle and if CSF is present in the drop it produces a halo around the blood circle.
