Overview
Cerebrospinal fluid (CSF) surrounds the brain and spinal cord and provides a cushion to protect them from injury. There are three protective 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 it 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
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.
- Dizziness.
- 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.
- Meningitis.
Causes
CSF leaks may be caused by injuries, procedures or other factors.
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:
- Sneezing.
- Coughing.
- Straining to have a bowel movement.
- Lifting heavy objects.
- Falling.
- Stretching.
- Exercise.
When there is no surgery or procedure prior to the start of a CSF leak, it is called a spontaneous CSF leak.
Risk factors
There are some factors that may increase your risk of a spinal or cranial 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.
- Obesity.
- Obstructive sleep apnea.
- Head trauma.
- Tumor at the skull base.
- Irregularities of the skull base or inner ear.
Complications
If a cranial CSF leak is not treated, complications may occur. Possible complications include meningitis and air entering the spaces surrounding the brain, known as tension pneumocephalus. Spinal CSF leaks that aren't treated may lead to bleeding on the surface of the brain, known as subdural hematomas.