Cerebrospinal fluid leak

A cerebrospinal fluid leak (CSF leak) is a medical condition where the cerebrospinal fluid (CSF) in the brain or spinal cord leaks out of one or more holes or tears in the arachnoid and dura mater. A spinal CSF leak can also be caused by meningeal diverticula or CSF-venous fistula not associated with an epidural leak.

CSF leaks are often further classified according to the cause. An iatrogenic or traumatic CSF leak has an identified cause such as a lumbar puncture (noted by a post-dural-puncture headache), surgery or physical trauma; while a spontaneous cerebrospinal fluid leak has an unknown cause. CSF leaks are associated with heritable connective tissue disorders including Marfan syndrome and Ehlers-Danlos syndrome.

Signs and symptoms

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

Patients with a spinal leak may suffer 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. Patients with a cranial leak are more likely to suffer intracranial hypertension (high CSF pressure), and are at risk of meningitis. Some patients with either a cranial or 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.

Diagnosis

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

Routine imaging assessment should begin with contrast-enhanced brain MRI with sagittal reformats. Brain MRI should be assessed for signs of SEEPS :

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

For suspected spinal CSF leaks, spine imaging should 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 spontaneously. 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.

External links

Classification	ICD-10-CM
External resources	MedlinePlus: 001068