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What is Halo sign is positive and handkerchief test is negative in: and explain in detail?
To distinguish CSF rhinorrhoea from simple rhinorrhoea of rhinitis the following tests can be done: 1)Handkerchief test:Mucus stiffens the handkerchief but CSF does not. 2)Halo sign/Target 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.