Rhinorrhea is basically the discharge of fluid from the nose. It can also be called runny nose.
Cerebrospinal fluid is a fluid that surrounds the brain and the spinal cord. The CSF provides nutrition to the brain, it helps in protecting the brain and it aids in waste removal from the brain.

Literally everybody has suffered a runny nose at various points in their life. A runny nose could be caused by a common cold, certain allergies, freezing weather.

Once in a long while, notwithstanding, a runny nose can be brought about by a condition called cerebrospinal fluid (CSF) rhinorrhea, which is the point at which the liquid that encompasses the brain(CSF) leaks into the nose. A complication from surgery or injury are capable of causing CSF Rhinorrhea.

Causes

As stated earlier, Cerebrospinal fluid surounds the brain and spinal cord and this CSF is contained by a certain connective tissue called dura mater. CSF spills into certain cavities present in your head and comes out through the nose when there is a tear on that dura mater.

CSF rhinorrhea can be caused by the following:

• Surgical complications

• Some congenital defects

• Traumatic brain injury can also be a cause

• When there is a rise in intracranial pressure(pressure inside the head)

• It could also be spontaneous CSF rhinorrhea

Symptoms

• fluid that is thin and clear flowing from the nose

• increased flow of fluid from the nose when the person bends forward with the head facing downwards

• absence of smell

• worsening of the runny nose when the person changes position

• because of the constituents of CSF, there could be salty taste in the mouth

• migraine and frequent tiredness

Distinction between common runny nose and CSF leak

Runny nose	CSF Leak
The discharge from the nose can either be clear or colored. It could could also be thin or thick	The discharge from the nose is clear and thin
Drugs for cold and allergies can improve it	Drugs for cold and allergies do not improve it
Loss of smell is not usually involved	Loss of smell can be involved
There is discharge from both nostrils	There is discharge from one nostril

Complication

There could be spread of bacterial infection from the nose, through the tear in the dura mater into the brain coverings. This could lead to bacterial meningitis which is a severe infection.

Diagnosis

CT scans and MRI scans can be done to confirm CSF rhinorrhea.

Also, a sample of the fluid running from the nose can be taken and tested for the presence of "beta-2-transferrin" protein present only in CSF.

Treatment

Surgery can used to used to identify the site of the leak and rectify it.

Sometimes, a conservative approach of just observing can be taken as some CSF leaks tend to resolve over time.

Conclusion

CSF rhinorrhea is a condition that should be given great observation. One might be suffering constant running nose, thinking it's the type caused by common cold, not knowing that it could be CSF Rhinorrhea.