Halo sign is most consistent with which condition?

• A. Cerebrospinal fluid leak
• B. Bacterial infection
• C. Arthritis
• D. None

Answer: (A)

The halo sign shows clear cerebrospinal fluid around a central blood clot on a dressing. CSF leaks occur when there’s a breach in the meningeal layers, often from a basilar skull fracture after head trauma. CSF is clear and watery, so when it mixes with blood it can form a pale ring around the central clot, which is the halo you see. This visual cue points to a CSF leak rather than ordinary nasal discharge or a simple wound.

In practice, treat this as a potential skull fracture: avoid nose or ear instrumentation, keep the patient calm and still, monitor for neurologic changes, and seek advanced care promptly. The other options don’t produce this halo pattern—arthritis involves joints, and a bacterial infection would typically present with purulent drainage rather than a clear halo around a clot. None wouldn’t explain the CSF-specific sign.