Often, when referring to any kind of cerebrospinal fluid leak, the non-specific term CSF leak is used. Few realize that a CSF leak may arise in the head OR in the spine, AND that these are two different disorders. Let’s try to clear up some of the confusion.
What is a cranial CSF leak?
A cerebrospinal fluid (CSF) leak in the head—most often evident as CSF dripping from the nose or ear—is a cranial CSF leak.
What is a spinal CSF leak?
A cerebrospinal fluid (CSF) leak along the spine is a spinal CSF leak. This is due to a hole or tear in the dura mater around the spinal cord that normally holds the fluid in.
Here are a few of the misconceptions:
Misconception #1
One of the most common misconceptions by healthcare professionals and the general public is that cranial CSF leaks and spinal CSF leaks are the same disorder.
This is FALSE.
A spinal CSF leak involves a loss of CSF volume from a leak at the level of the spine. If a patient has symptoms of low CSF volume such as a positional headache, even if they have fluid dripping from their nose, a search for a spinal CSF leak should be undertaken. Note that not every positional headache is due to intracranial hypotension.
Misconception #2
Individuals with spinal CSF leaks are at increased risk of meningitis just as we see in patients with cranial CSF leaks.
This is FALSE.
A cranial CSF leak involves an opening between the brain and the rest of the body, so there is a risk of entry of bacteria or other microbes into the brain, causing meningitis.
A spinal CSF leak usually involves a leak into soft tissues without a communication through the skin. Unless there is a break in the skin, there is no increased risk of meningitis.
Extra immunizations are recommended for patients with cranial CSF leaks to attempt to reduce risk.
Misconception # 3
The underlying causes of spontaneous cranial and spinal CSF leaks are the same.
This is FALSE.
Trauma and surgery can certainly cause cranial CSF leaks and spinal CSF leaks, but the types of trauma and types of surgery are usually different.
The underlying causes of spontaneous cranial versus spinal CSF leaks are quite different. Intracranial hypertension (high pressure in the head) is well-documented in the published literature as an underlying cause of spontaneous cranial CSF leaks but appears to be infrequently associated with spontaneous spinal CSF leaks. More research is needed.
Spontaneous spinal CSF leaks are associated with several hereditary disorders of connective tissue, whereas this association has not been established with cranial CSF leaks.
Bone spurs along the spine are another cause of spinal CSF leaks.
Misconception #4
The diagnostic testing for cranial CSF leaks and spinal CSF leaks is the same.
While CT and MRI are used for both, the specifics of imaging differ. Spontaneous cranial CSF leaks and spinal CSF leaks have DIFFERENT symptoms, complications, underlying causes, diagnostic testing, and treatment approaches.
You can learn more about spinal CSF leaks, which is our focus, here on our website.