What Is a Cerebrospinal Fluid (CSF) Leak?

The brain and spinal cord are protected by three membranes (meninges). When the outermost layer of the meninges, the dura, is injured or punctured — often as a result of a head injury, certain medical procedures, or an increase of pressure in the skull — a cerebrospinal fluid (CSF) leak may occur. Cerebrospinal fluid is a clear liquid that flows in and around the brain and spinal cord to protect from injury and transfer nutrients.

Types of cerebrospinal fluid leaks

Cerebrospinal fluid leaks are categorized according to the location of the leak: Spinal CSF leaks originate from the dura around the spinal column, whereas cranial CSF leaks originate from the dura around the skull.

Symptoms

Symptoms of CSF leaks vary and are dependent on the type of leak.

Spinal CSF leak symptoms

• Headache in the back of the head, which may worsen when standing, coughing, or straining, may improve when lying down, and may start suddenly
• Dizziness
• Vision changes
• Nausea and/or vomiting
• Changes in hearing
• Ringing in the ears
• Confusion
• Neck pain and/or shoulder pain

Cranial CSF leak symptoms

• Clear, watery drainage from one side of the nose or ears
• Hearing loss
• Loss of smell
• Metallic taste in mouth

Causes

The causes of CSF leaks differ, depending on the type of leak.

Spinal CSF leak causes

Potential causes of spinal CSF leaks include the following:

• Prior spinal surgery
• Spinal tap/lumbar puncture
• Injury to the head or spine
• Irregular connections between dura mater and veins (CSF-venous fistulas)
• Epidural in the spine for pain relief (including epidurals given during labor/delivery)
• Irregularities of the dura mater around the nerve roots in the spine

Cranial CSF leak causes

Potential causes of cranial CSF leaks include the following:

• Sinus surgery
• Head injury
• Malformations of the inner ear
• Increased pressure in the brain

A CSF leak could be triggered by seemingly minor situations, including the following:

• Exercise
• Falls
• Heavy lifting
• Coughing
• Sneezing
• Straining during a bowel movement
• Stretching

Risk factors

Spontaneous CSF leaks (not caused by surgery or a medical procedure) are more common after the age of 30 and in individuals assigned female at birth. Other risk factors for CSF leaks include the following:

Spinal CSF leak risk factors

Factors that increase the risk of developing a spinal CSF leak include the following:

• Previous spinal surgery or other procedures involving or surrounding the spine
• Connective tissue disorders, such as Marfan syndrome or Ehlers-Danlos syndrome

Cranial CSF leak risk factors

Factors that increase the risk of developing a cranial CSF leak include the following:

• Obstructive sleep apnea
• Tumors at the base of the skull
• Previous surgery involving or surrounding the skull
• Head trauma
• Irregularities of the base of the skull or inner ear

Additional source: NewYork-Presbyterian Hospital