Cerebrospinal Fluid Leak

A cerebrospinal fluid leak (CSF leak) is a medical condition where the cerebrospinal fluid (CSF) surrounding the brain or spinal cord leaks out of one or more holes or tears in the dura mater. A cerebrospinal fluid leak can be either cranial or spinal, and these are two different disorders. A spinal CSF leak can be caused by one or more meningeal diverticula or CSF-venous fistulas not associated with an epidural leak.

CSF leaks are either caused by trauma including that arising from medical interventions, or have no known cause known as spontaneous cerebrospinal fluid leaks (sCSF leaks). Traumatic causes include a lumbar puncture noted by a post-dural-puncture headache, and other trauma such as from a fall or accident. Spontaneous CSF leaks are associated with heritable connective tissue disorders including Marfan syndrome and Ehlers–Danlos syndromes.

Signs and symptoms

The most common symptom of a CSF leak is a fast-onset, extremely painful orthostatic headache or thunderclap headache.

A spinal leak may cause spontaneous intracranial hypotension (low CSF pressure) because the body cannot replenish the CSF fast enough to keep pace with the leak. As a result, the brain may sag inside the skull and into the foramen magnum, which is visible (and measurable) with an MRI of the brain. A cranial leak is more likely to cause intracranial hypertension (high CSF pressure), which carries a risk of meningitis. Both a cranial and spinal leak can fluctuate between high and low CSF pressure.

While high CSF pressure can make lying down unbearable, low CSF pressure due to a leak can be relieved by lying flat on the back.

Other symptoms of a CSF leak can include neck pain, photophobia, dizziness, gait disturbances, tinnitus, visual disturbances, brain fog, nausea, fluid dripping from the nose or ears, and a metallic taste in the mouth. An untreated CSF leak can result in coma or death.

Movement disorders are uncommon in spontaneous CSF leaks but occasionally can be one of the major components of the clinical presentation.

Causes

A cerebrospinal fluid leak can be a rare complication of an anterior cervical discectomy and fusion (ACDF). One study suggested a CSF leak to follow from 0.5% of operations. Another study suggests a CSF leak to follow from 1% of operations. In most of these cases repair is successful.

Diagnosis

CSF leaks are frequently misdiagnosed as migraine, Chiari malformation, dysautonomia or conversion disorder.

Routine imaging assessment uses contrast-enhanced brain MRI with sagittal reformats.: Imaging can assess for the following:

• Subdural fluid collections
• Enhancement of the meninges
• Engorgement of venous structures
• Pituitary swelling
• Sagging of the brain

For suspected spinal CSF leaks, spine imaging can be used to guide treatment.

Other imaging can be helpful in diagnosing a CSF leak, and in identifying its location, typically using a CT scan or an MRI scan. A myelogram can be used to more precisely identify the location of a CSF leak by injecting a dye to further enhance the imaging. However, CSF leaks are frequently not visible on imaging.

For patients with recalcitrant spontaneous intracranial hypotension and no leak found on conventional spinal imaging, digital subtraction myelography, CT myelography and dynamic myelography (a modified conventional myelography technique) should be considered to rule out a CSF-venous fistula. In addition, presence of a hyperdense paraspinal vein should be investigated in imaging as it is highly suggestive of a CSF venous fistula.

Fluid dripping from the nose (CSF rhinorrhoea) or ears (CSF otorrhea) should be collected and tested for the protein Beta-2 transferrin which would be highly accurate in identifying CS fluid and diagnosing a cranial CSF leak.

Treatment

Symptomatic treatment usually involves analgesics for both cranial and spinal CSF leaks. Caffeine and short-term bed rest can alleviate symptoms of low CSF pressure, while elevated rest and acetazolamide can alleviate symptoms of high CSF pressure.

Sometimes a CSF leak will heal on its own. Otherwise, symptoms may last months or even years. An epidural blood patch is the typical treatment for a CSF leak, where up to 20 cubic centimeters of the patient's blood is drawn, then injected into either the lumbar or cervical spine, close to the known or suspected site of the leak. Fibrin glue patching is an alternative where blood patching is unsuccessful. If the site of the leak is known, neurosurgical repair of the dura mater is an option.

Surgery to treat a CSF-venous fistula in CSF leak patients is highly effective.

The use of antibiotics to prevent meningitis in those with a CSF leak due to a skull fracture is of unclear benefit.