What is CSF?  What is a CSF leak?

Cerebrospinal fluid (often referred to as “CSF”) is the fluid that sits around the brain and spinal cord.  As the brain sits in the skull, it is surrounded and cushioned by the CSF.  The fluid is also thought to help circulate nutrients around the brain.  The fluid is clear and looks like water.

The brain and CSF are typically not exposed directly to the outside world; they are protected inside the skull.  In some situations, the CSF can start to leak out of its usual location.  Sometimes, it can leak out of the nose.  When that happens, it is called a CSF leak.  For a leak to happen, there has to be a hole in the layers of tissue around the brain and CSF.  The hole has to typically involve a few different layers of tissue to allow the fluid to leak out of the nose.

When there is a CSF leak, there is typically drainage of watery fluid from the nose.  The drainage can be steady.  That can make it look like the drainage from a leaky water faucet.  The constant drainage can be annoying, but can also create a health problem.  Just as fluid can leak out of the hole, bacteria can enter through the hole and create an infection called meningitis.  Meningitis is a serious infection that can lead to many problems.

What causes a nasal CSF leak?

Some of the causes of CSF leaks include:

  • Surgery. Some common procedures that can lead to a CSF leak include brain surgery, nasal surgery, and sinus surgery.
  • Injuries involving the nose, face, and head.
  • High CSF pressure

How are CSF leaks diagnosed?

Making the diagnosis of a CSF leak can be challenging.  In some situations, there may be a lot of fluid leaking from the nose.  The fluid can be collected and sent to a lab for analysis, and this may help make the diagnosis.  The test that is used commonly is called a beta-2-transferrin assay.  If beta-2-transferrin is detected, it is typically diagnostic of a CSF leak.
It is also important to determine where the leak is located.  One of the tests that is very helpful to find the location is a sinus and head CT scan.  Examination of the nose with an endoscope can also help.  Based on your symptoms and the findings from an exam, a specialist who treats CSF leaks can determine what sorts of tests would be most helpful.
Once the diagnosis is made and the location is determined, a plan can be made to repair the hole that is allowing the fluid to leak.  Some cases may heal on their own, but repairing the hole often requires surgery.

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