Cerebrospinal fluid (CSF) surrounds the brain and spinal cord and provides a cushion to protect them from injury. There are three layers that surround the spinal cord and brain. When there is a hole or tear in the outermost layer, a CSF leak occurs. The hole or tear in this outer layer, called the dura mater, allows some of the fluid to escape.
There are two distinct types of CSF leaks: spinal CSF leaks and cranial CSF leaks. Each type has different symptoms, causes and treatments.
A spinal CSF leak occurs anywhere in the spinal column. The most common symptom of a spinal CSF leak is a headache.
A cranial CSF leak occurs in the skull, and often causes symptoms such as clear fluid leaking from the nose or ear.
Some CSF leaks may heal with bed rest and other conservative treatment. Many CSF leaks need a patch to cover the hole or surgery to repair the leak.
Symptoms vary between spinal and cranial CSF leaks.
Spinal CSF leaks
The most common symptom of a spinal CSF leak is a headache. These headaches usually:
- Cause pain in the back of the head.
- Improve when lying down.
- Worsen when standing up.
- May start or worsen when coughing or straining.
- Rarely, start suddenly. When this happens, it is called a "thunderclap" headache.
Other symptoms of spinal CSF leaks may include:
- Neck or shoulder pain.
- Ringing in the ears.
- Changes in hearing.
- Nausea or vomiting.
- Changes in vision.
- Changes in behavior or ability to think clearly.
Cranial CSF leaks
Cranial CSF leak symptoms may include:
- Clear, watery drainage from one side of the nose or ear.
- Hearing loss.
- A metallic taste in the mouth.
Spinal CSF leaks may be caused by:
- A spinal tap, also called a lumbar puncture.
- An epidural in the spine for pain relief, such as during labor and delivery.
- An injury to the head or spine.
- Bone spurs along the spine.
- Irregularities of the dura mater around the nerve roots in the spine.
- Irregular connections between dura mater and veins. These are referred to as CSF-venous fistulas.
- Prior surgery on the spine.
Cranial CSF leaks may be caused by:
- A head injury.
- Sinus surgery.
- Increased pressure in the brain.
- Malformations of the inner ear.
Sometimes CSF leaks develop after very minor events:
- Straining to have a bowel movement.
- Lifting heavy objects.
When there is no surgery or procedure prior to the start of a CSF leak, it is called a spontaneous CSF leak.
Risk factors for spinal CSF leaks include:
- Having a previous surgery or procedure on or around the spine.
- Connective tissue disorders such as Marfan syndrome or Ehlers-Danlos syndrome, which often also cause joint hypermobility and dislocations.
Risk factors for cranial CSF leaks include:
- Having a previous surgery on or around the skull.
- Obstructive sleep apnea.
- Head trauma.
- Tumor at the skull base.
- Irregularities of the skull base or inner ear.
If a cranial CSF leak is left untreated, complications may occur. Possible complications include meningitis and tension pneumocephalus, which is when air enters the spaces surrounding the brain. Untreated spinal CSF leaks may lead to subdural hematomas, or bleeding on the surface of the brain.
Spinal CSF leak
Your healthcare professional will likely start by asking about your medical history and conducting a physical exam.
Tests to diagnose a spinal CSF leak may include:
- Magnetic resonance imaging (MRI) with gadolinium. An MRI scan uses a magnetic field and radio waves to produce detailed images of the brain, spinal cord and other areas of the body. Using MRI with gadolinium makes it easier to see any changes in the spine that result from a CSF leak. Gadolinium is a substance called a contrast agent that highlights tissues in the body.
- Radioisotope cisternography. This test involves measuring the CSF pressure and then injecting a chemical into the space surrounding the spinal cord. Then, several images of the area are taken over a 24-hour period. These images watch for changes in the flow of CSF that may indicate a leak.
- Myelography. This imaging test uses a contrast dye and X-rays or computed tomography (CT) to take detailed pictures of the spine. It can find the exact location of a CSF leak and helps to determine the most appropriate treatment plan.
- Spinal tap. This test also is called lumbar puncture. It involves placing a needle in the spinal column to measure the pressure of CSF inside the spinal column. It is usually performed as part of another test for CSF leak. For example, a spinal tap is required at the start of myelography or cisternography.
Cranial CSF leak
Your healthcare professional will likely start with your medical history and a physical exam. The physical exam includes close evaluation of your nose and ears. You may be asked to lean forward to check for any nasal discharge, which may be collected and sent to a lab for testing.
Tests to diagnose a cranial CSF leak may include:
- MRI with gadolinium. An MRI scan may be used to help detect a CSF leak inside the brain. Using it with gadolinium, a contrast agent, helps to highlight irregularities in the brain and locate the source of a CSF leak.
- Tympanometry. This test uses a handheld device called a tympanometer. The probe on the tympanometer is inserted into the ear to measure middle ear function and check for fluid. Clear fluid coming out of the ear is a symptom of a CSF leak.
- CT cisternography. This test is considered the gold standard for diagnosing and locating cranial CSF leaks. It uses a CT scan and a contrast dye to locate CSF leaks anywhere in the skull base. This test can show exactly where a CSF leak is, and help to determine the most appropriate treatment plan. High-resolution CT provides images in even greater detail and also may be used.
Some CSF leaks improve with bed rest alone, but most need treatment.
Treatments for spinal CSF leaks may include:
- Epidural blood patch. This treatment involves taking a sample of your own blood, then injecting it into the spinal canal. The blood cells form a clot, which can create a patch to cover the area where the CSF is leaking.
- Fibrin sealant. Fibrin sealant is special glue made from substances in human plasma that help with blood clotting. Used alone or mixed with your blood, it is injected into the spinal canal to cover the hole and stop the CSF leak.
- Surgery. Some CSF leaks need surgery. Surgery is performed if the other treatment options don't work and the precise site of the leak is known. There are several types of surgical treatments that repair CSF leaks. Surgery may involve repairing the CSF leak with stitches or grafts made from patches of muscle or fat.
- Trans-venous embolization. This minimally invasive procedure is used only for CSF-venous fistulas. CSF-venous fistulas are irregular connections that occur in the spine and allow CSF fluid to leak into the blood vessels. Trans-venous embolization stops the leak by gluing shut the fistula from inside the affected vein.
Some cranial CSF leaks, such as those caused by trauma, may improve with conservative measures such as:
- Bed rest.
- Elevating the head of the bed.
- Taking stool softeners to prevent straining.
Other cranial CSF leaks require surgical repair.
Preparing for an appointment
After discussing your symptoms with your healthcare professional, you might receive a referral to see a doctor trained in brain and spine conditions for further evaluation. Doctors with this training include neurologists, neurosurgeons and ENTs.
Here's some information to help you get ready for your appointment.
What you can do
Make a list of:
- Your symptoms, including any that may seem unrelated to the reason for which you scheduled the appointment, and when they began.
- Key personal information, including major stresses or recent life changes.
- All medicines, vitamins or other supplements you take, including doses.
- Questions to ask your healthcare team.
Bring with you to the appointment recent test results and scans of your brain and spine. Take a family member or friend along, if possible, to help you remember the information you receive.
For CSF leaks, questions to ask your healthcare provider include:
- What is likely causing my symptoms or condition?
- What tests do I need?
- Is my condition likely temporary or long-lasting?
- What is the best course of action?
- Would losing weight help my condition?
- I have these other health conditions. How can I best manage them together?
- Are there restrictions I need to follow?
- Should I see a specialist?
- Are there brochures or other printed material that I can have? What websites do you recommend?
Don't hesitate to ask other questions.
What to expect from your doctor
Your healthcare professional is likely to ask you questions, including:
- Have your symptoms been continuous or do they come and go?
- How severe are your symptoms?
- What, if anything, seems to improve your symptoms?
- What, if anything, seems to worsen your symptoms?