I thought it was a runny nose, but it's fluid flowing from the brain? In such cases, you must go to the hospital.

Runny nose is an indicator of health. Many people with rhinitis consider a runny nose to be nothing serious, but there are times when you should never ignore it and need to visit a hospital.

Professor Manjun Park of Inha University Hospital's ENT Department said at the "2nd Nose Day" event held by the Korean Rhinologic Society this April, "If nasal discharge continues from only one side, it is necessary to visit a hospital," adding, "Although rare, it could be cerebrospinal fluid rhinorrhea caused by tumors or tissue defects in the nasal roof."

Cerebrospinal fluid refers to the clear liquid that surrounds and flows around the brain and spinal cord. It protects the brain and spinal cord from external shocks and supplies nutrients. If you hit your head hard in a traffic accident or if there is tissue loss near the base of the brain (the floor of the cerebrum) due to conditions such as a pituitary tumor, cerebrospinal fluid can leak out through this area and flow down the nose. This is because the nose is located below the brain.

The main symptom of cerebrospinal fluid rhinorrhea is a clear, non-viscous fluid resembling runny nose that flows out from one nostril. Since the nose is connected to the mouth, a slight bitter or salty taste may also be felt in the mouth. When coughing, sneezing, or tilting the head forward, which increases intracranial pressure, the amount of cerebrospinal fluid leaking can become particularly large. Mild headaches may also accompany it.

Cerebrospinal fluid is difficult to distinguish from clear nasal discharge that flows at the beginning of allergic rhinitis, so it is advisable to go to a hospital for diagnosis. Normal cerebrospinal fluid is known to have a glucose level of 50-80 mg/dL, so the hospital collects a fluid suspected to be cerebrospinal fluid for a blood sugar test. If the glucose level is 30 mg/dL or higher, it is diagnosed as cerebrospinal fluid rhinorrhea. To accurately identify the site of cerebrospinal fluid leakage, a computed tomography (CT) scan or magnetic resonance imaging (MRI) may be necessary.

If the defect in the cerebrospinal fluid leak is mild, natural healing can be attempted through non-surgical treatment. However, hospitalization may be necessary. This is because absolute rest must be maintained with the head elevated 10-15 degrees while lying in bed to prevent an increase in intracranial pressure. Any actions that can worsen rhinorrhea, such as coughing, sneezing, or blowing the nose, are strictly prohibited. If the defect is large, surgical reconstruction of the defect may be required. This is done by inserting an endoscope into the nasal cavity to completely suture the defect area.

If cerebrospinal fluid leakage is left untreated, complications such as meningitis, which involves inflammation of the meninges surrounding the brain and spinal cord, can occur. There are reports indicating that patients with ongoing cerebrospinal fluid leakage have a 19% chance of developing meningitis. If suspected, it is essential to visit a hospital for treatment.

Meanwhile, there are various other diseases that can be estimated by observing nasal discharge. If the nasal discharge is clear and transparent after blowing your nose, it may indicate early-stage cold or allergic rhinitis. If the nasal discharge is fluorescent or greenish and has an unpleasant odor, it is likely to be acute or chronic sinusitis. If there is an increase in nasal discharge after gum disease or dental implant procedures, it may suggest odontogenic sinusitis. This is caused by inflammation near the upper molars spreading to the sinuses. When accompanied by fungi or other pathogens, it can produce an unpleasant smell. Additionally, if nasal discharge is unusually abundant during meals, it may indicate vasomotor rhinitis. If sneezing and nasal discharge occur when exposed to cold environments or dust, allergic rhinitis may be suspected.