eMedicine Specialties > Radiology > Brain/Spine

Cerebrospinal Fluid, Leak

Hugh J F Robertson, MD, DMR, FRCPC, FRCR, FACR, Professor Emeritus of Radiology, Professor of Clinical Radiology, Louisiana State University Health Sciences Center, New Orleans; Clinical Professor of Radiology, Tulane University School of Medicine; Active Staff, Department of Radiology, University Hospital
Enrique Palacios, MD, FACR, Professor of Radiology, Neuroradiology, Tulane University Medical Center, New Orleans; Michael G D'Antonio, MD, Clinical Associate Professor of Radiology, Louisiana State University Health Sciences Center, New Orleans; Consulting Staff Radiologist, Jefferson Radiology Associates, Inc, West Jefferson Medical Center

Updated: Oct 26, 2009

Introduction

Background

Cerebrospinal fluid (CSF) leak may occur from the nose (rhinorrhea), from the external auditory canal (otorrhea), or from a traumatic or operative defect in the skull or spine. The fluid leak is a result of meningeal dural and arachnoid laceration with fistula formation. Blunt trauma is the most common cause.

Coronal CT image of the temporal bone demonstrates a bone defect (small arrows) in the tegmen tympani with a protruding soft-tissue meningoencephalocele (large arrows). This patient had cerebrospinal fluid otorrhea after mastoidectomy.

Coronal fast spin-echo T2-weighted image in the same patient as in Image 11 demonstrates herniation of meninges and brain tissue (arrows) with adjacent cerebrospinal fluid into the postmastoidectomy tegmen tympani defect. This finding is consistent with a meningoencephalocele of the temporal bone.

Acute posttraumatic cerebrospinal fluid rhinorrhea. This coronal magnetic resonance cisternogram demonstrates a left-sided cerebrospinal fluid leak through the cribriform plate (small arrows), which was clinically suspected. The image also shows a right-sided meningocele (large arrow) protruding through the cribriform plate, which was not suspected but was surgically repaired at the same time as the left cribriform cerebrospinal fluid leak site.

Lateral 24-hour cranial scintigraphic image from a nuclear medicine cisternographic study in a patient with clinically evident right-sided cerebrospinal fluid rhinorrhea. Image demonstrates increased tracer accumulation in the nasal region (arrow).

Pathophysiology

Normal adult subarachnoid fluid has a circulating volume of 90-150 mL. Approximately 500 mL of cerebrospinal fluid (CSF) is produced daily, primarily from the ventricular choroid plexuses. Circulating CSF is absorbed into the venous circulation, mainly through the cranial arachnoid granulations and spinal arachnoid villi.

Normal CSF pressure is 100-200 mm of water. The normal CSF protein content is 20-45 mg/dL, and the normal CSF glucose range is 50-100 mg/dL, which is 60% of the measured serum glucose value. However, nasal mucous secretions and tears also have detectable glucose content. Therefore, tests used to identify CSF by its glucose content are often false positive (in 45-75% of cases). The absence of glucose tends to exclude CSF as the leaking fluid.

The enzyme beta-2 transferrin (B2Tr) is produced in the brain by neuraminidase activity and is present in CSF, perilymph, and ocular aqueous humor but not in sinonasal mucous secretions and tears.³ This feature is the basis for a specific test for CSF based on immunoelectrophoresis. B2Tr may be found in blood serum in liver disease, such as in chronic alcoholism and in patients with inborn errors of glycoprotein metabolism or genetic variants of transferrin. Beta-trace protein is prostaglandin D2 synthase. It is produced in epithelial cells of the choroid plexus and meninges and is found in CSF, perilymph, seminal fluid, and urine. It is approximately 35 times more concentrated in CSF than in blood serum. Immunoelectrophoretic assay of beta trace protein has been reported to have high specificity and sensitivity for CSF detection.^4,5

CSF rhinorrhea

Causes of CSF rhinorrhea include (1) blunt head trauma; (2) sequelae of skull-base surgery,⁶ commonly functional endoscopic sinus surgery (FESS), transsphenoidal pituitary surgery, translabyrinthine acoustic schwannoma, and mastoid surgery with intact tympanic membrane; (3) destructive skull-base lesions, including neoplasms (both benign and malignant), and empty sella; (4) developmental defects of the ethmoid, sphenoid, frontal, or petrous temporal bones with the formation of a meningocele or meningoencephalocele (with an intact tympanic membrane); and (5) fracture of the petrous temporal bone or other destructive processes in which CSF in the middle ear drains to the nose in the presence of an intact tympanic membrane.^7,8

Less than 5% of all cases of CSF rhinorrhea are spontaneous. Most cases of CSF rhinorrhea begin soon after a head injury and cease spontaneously within 7-180 days.

CSF otorrhea

Artist's rendering of a tegmen tympani bone defect with a herniated meningoencephalocele.

With a translabyrinthine fistula, CSF mixes with perilymph in the cochlea or vestibule and forms perilymphatic hydrops with displacement or perforation of the maldeveloped stapes footplate; the fluid leaks into the middle ear.¹¹ Wide cochlear aqueduct syndrome is a controversial and doubtful entity in adult patients because the aqueduct is filled with fibrous tissue and not functional beyond childhood.

Pneumocephalus

Pneumocephalus can occur in up to one third of all patients with posttraumatic or spontaneous CSF leak.¹² This condition is likely the result of the pressure gradient created during respiration, sneezing, or nose blowing.

Spinal CSF leak

Spinal CSF leaks can occur as a result of (1) blunt or penetrating trauma¹³ ; (2) postoperative sequela with leakage through a dural tear or incision; (3) lumbar puncture¹⁴ ; (4) inadvertent meningeal puncture during epidural anesthesia; (5) spontaneous leakage from 1 or more spinal nerve root sleeves, particularly in the thoracic and lumbar areas; and (6) Valsalva maneuver during excessive weightlifting.¹⁵

Increased intracranial pressure facilitates the development of CSF leaks. Meningeal dysplasia (as in Marfan syndrome) may also contribute to the development of CSF leak in some patients.

Spontaneous intracranial hypotension syndrome

Spontaneous intracranial hypotension syndrome (SIHS) can result from a persistent CSF leak. SIHS is usually spinal and seldom originates from the skull base (eg, ethmoidal defects). Frequently, SIHS and persistent orthostatic headache after lumbar punctures can be successfully treated by lumbar epidural blood patch.^16,17,18

Frequency

United States

Cerebrospinal (CSF) rhinorrhea occurs in 2-6% of patients with head injury. Rhinorrhea or otorrhea occurs in up to 30% of patients with a skull-base fracture. Head trauma accounts for 50-80% of all cases of CSF leak, and up to 16% are iatrogenic.

Postoperative CSF leak has been noted in 0.5-15.0% of patients with transsphenoidal surgery, particularly after reparative operations.¹⁹ CSF leak has been reported in 5.0-12.5% of translabyrinthine acoustic schwannoma surgeries.²⁰ Functional endoscopic sinus surgery (FESS) is a common procedure, with CSF leak occurring in 1.0-2.5%, but 90% of leaks are detected and repaired intraoperatively.

About 4% of CSF leaks are of spontaneous and nontraumatic causes (eg, developmental skull-based defects with meningocele, skull-base tumor, empty sella,²¹ osteomyelitis).

Mortality/Morbidity

Meningitis occurs in 25-50% of untreated traumatic cerebrospinal fluid (CSF) fistulas and in 10% of patients in the first week after trauma with head injury. The incidence of meningitis up to several years after spontaneous cessation of posttraumatic CSF leak is 10%. Meningitis-related mortality rates up to 20% have been reported, particularly when meningitis is due to antibiotic-resistant organisms.

• 50-85% of traumatic CSF leaks resolve spontaneously within 7 days, and almost all leaks cease within 6 months.
• CSF fistula of spontaneous origin is often intermittent, persisting in at least 60% of cases if untreated. The risk of meningitis is higher with spontaneous CSF fistula than with traumatic CSF fistula.
• CSF otorrhea after trauma ceases spontaneously more often than traumatic rhinorrhea and seldom recurs.

Sex

• No sexual predilection is reported for traumatic cerebrospinal fluid (CSF) fistula.
• For postsurgical and spontaneous CSF leaks, the female-to-male ratio is 2:1.

Age

• No age predilection is reported for traumatic cerebrospinal fluid (CSF) fistula.
• Postsurgical and spontaneous CSF leaks are most common in adults older than 30 years.

Anatomy

Cerebrospinal fluid (CSF) leak resulting from trauma occurs usually with fractures of ethmoid, sphenoid, or petrous temporal bones.²² The ethmoid bones are particularly vulnerable to trauma. The orbital plates of the frontal bone do not cover the ethmoid bones completely; therefore, the thin and perforated cribriform plates are partially unprotected.

The dura is thinnest at and adherent to the cribriform plates and adjacent ethmoid sinus medial segments. The anterior ethmoidal arteries course in grooves on the surface of the ethmoid bones. In addition, multiple developmental defects occasionally occur in the sphenoid bone and in the floor of the middle cranial fossa. Because of these vascular grooves in the ethmoid bones and cribriform plates and because multiple anatomic defects are frequently present, it is sometimes difficult to demonstrate a fracture or developmental defect of the ethmoid bone in association with a CSF fistula.

Presentation

CSF leak after trauma

Cerebrospinal fluid (CSF) leak from the fistula occurring after head trauma consists of watery, blood-stained fluid that abruptly leaks from 1 or both nostrils or an external auditory canal. Two thirds of patients with these fistulas present within 48 hours of their head injury. Almost all of these fistulas occur within 3 months of injury. Occasionally, the fistula appears many months or years after injury, with a sudden gush of fluid or meningitis; these episodes are sometimes recurrent. CSF leak occurs often without nasal congestion, sneezing, lacrimation, or aural discharge.

Rhinorrhea may occur intermittently and can increase on bending forward, with a Valsalva maneuver or jugular vein compression. Nasal vasoconstrictor or antihistamine therapy does not affect the leak. Headache is sometimes but not always present. The patient may have physical signs of skull-base fracture, including periorbital ecchymosis or edema, mastoid-area skin ecchymoses, and cranial nerve deficits.

Frontal trauma may result in anosmia from an injury to the olfactory nerves, tracts, or orbitofrontal cortex; visual deficit from an injury to the optic nerve, optic globe, or extraocular muscle; or fractures of the orbit medial wall and floor.²³ A fracture of the temporal bone may be associated with a blood clot and hemorrhagic fluid in the external auditory canal, a perforated tympanic membrane, and conductive or sensorineural hearing loss. Transverse fractures of the petrous temporal bone result in injury to cranial nerves VII and VIII in 50% of patients. In addition, deafness may result from ossicular disruption. Longitudinal fractures of the temporal bone result in injury to cranial nerve VII in 25% of patients.

Labyrinthine injury may result in vertigo. Otitis media and meningitis may occur. Increased intracranial pressure and hydrocephalus may prolong a CSF leak that might otherwise cease spontaneously.

A ventriculostomy catheter in a patient with CSF leak is associated with an increased incidence of meningitis.²⁴

Pneumocephalus

Pneumocephalus can sometimes give an audible succussion splash with shaking of the head. Tension pneumocephalus occurs in rare cases and can result in an emergency with an acute change in the level of consciousness. The air must then be drained by inserting a needle through a twist drill hole in the cranial bone.

Spontaneous intracranial hypotension syndrome

Patients with spontaneous intracranial hypertension syndrome (SIHS) typically present with orthostatic headaches, which are maximal in intensity in the upright position and diminished in the recumbent position. Other symptoms include neck pain and stiffness, nausea, diplopia, dizziness, hearing loss, photophobia, visual field defects, facial numbness, and, occasionally, radicular pain in the arms. Patients may have a history of recent lumbar puncture, spinal trauma, or surgery. In SIHS, CSF pressure is usually 40-60 mm of water, but it is sometimes normal.

Preferred Examination

A suggested algorithm for the diagnosis of a cerebrospinal fluid (CSF) fistula follows.

1. Confirm or exclude the presence of CSF in leaking fluid by means of an immunoelectrophoretic study of the fluid for beta-2 transferrin (B2Tr) or, where available, beta-trace protein. For this specialized laboratory study, 0.5-1.0 mL of the fluid may be required. An absorptive sponge pad placed at or near the presumed site of fluid leak can facilitate the collection of the fluid.
2. Perform high-resolution, thin-section axial and coronal cranial and facial CT.²⁵ Include all of the paranasal sinuses and petrous temporal bones in the scans.
3. Perform magnetic resonance (MR) cisternography. This study may also be useful for detecting inactive fistulas.
4. CT cisternography or radionuclide cisternography may be useful if CT and MR cisternography do not show the CSF fistula.
   • Radionuclide cisternography may be useful to detect an intermittently active CSF fistula.
   • Cisternography with an intrathecal injection of radioisotope or nonionic iodinated myelographic contrast medium or noninvasive MRI cisternography usually localizes the CSF leak.
5. Brain and spinal MRI is useful in demonstrating meningocele and meningoencephalocele when associated with CSF leak, as well as for examining patients with spontaneous intracranial hypotension syndrome.²⁶
6. On occasion, the methods listed above do not help in localizing the CSF fistula, and surgical exploration is necessary.

Fluid leaking from the nose or external auditory canal must first be positively identified as CSF. Drops of fluid from a CSF leak placed on absorbent filter paper may result in the double-ring sign, which is a central circle of blood and an outer clear ring of CSF. Results of glucose, chloride, and total protein tests of the fluid are not specific or conclusive for CSF.

All methods of cisternography—radionuclide, CT, and MR—provide improved or optimal CSF fistula detection when the fistula is active and when a Valsalva maneuver or jugular venous compression is added to the imaging protocol. CSF fistula can usually be demonstrated by using some method of cisternography, but localization of the leak to the right or left nasal cavity may be difficult because of the tendency of the fluid to cross sides and flow from both nostrils.

Methods for detecting CSF fistulas with intrathecal injections of dye pose a risk of chemical meningitis. Methylene blue, indigo carmine, and phenolsulfonphthalein (PSP) dyes are no longer in use. Some otolaryngologists use a dilute solution of fluorescein to localize CSF fistulas both preoperatively and during surgery. Typically, 0.5 mL of a 10% fluorescein solution is injected into the lumbar subarachnoid space over more than 1 minute. Cotton pledgets are placed in the nose, as for radionuclide cisternography. The dye reaches the skull base in 6 hours and is present over the cerebral convexities in 24 hours. The pledgets are examined for green fluorescence in a dark room with ultraviolet light 6 hours after the intrathecal PSP injection.²⁷

Limitations of Techniques

Skull radiographs are of limited diagnostic use in cerebrospinal fluid (CSF) leaks, but they may show a skull fracture or suggest the presence of empty sella.

Computer-reconstructed coronal images are less accurate and are acceptable only until direct coronal images can be obtained.

Differential Diagnoses

Other Problems to Be Considered

Acute or chronic rhinitis (allergic, infectious, vasoactive)
Perforated otitis interna (serous, catarrhal)
Otitis externa
Foreign body in the external auditory canal

Radiography

Findings

Skull radiographs are of limited diagnostic use in cerebrospinal fluid (CSF) leaks, but they may show a skull fracture or suggest the presence of empty sella.

Computed Tomography

Findings

This patient presented with a spontaneous onset of cerebrospinal fluid rhinorrhea 10 years after a head injury. This coronal CT cisternogram was obtained after an intrathecal injection of contrast material (Omnipaque 300, 8 mL) into the lumbar thecal sac and subsequent positioning of the contrast agent in the head. The image demonstrates dense contrast medium layering in the empty sella and contained within the meningocele (arrow).

Axial CT image was obtained with the patient (same patient as in Image 4) in the supine position. Contrast medium has drained out of the meningocele, but a small amount remains in the sphenoid sinus around the meningocele.

Axial CT image of the same patient as in Image 9 demonstrates pneumocephalus in association with the spontaneous cerebrospinal fluid rhinorrhea and a septal bone defect in the left posterior ethmoid air cell.

Coronal CT image of the temporal bone demonstrates a bone defect (small arrows) in the tegmen tympani with a protruding soft-tissue meningoencephalocele (large arrows). This patient had cerebrospinal fluid otorrhea after mastoidectomy.

CT cisternography is performed with injection of 5-7 mL of nonionic myelographic contrast medium into the lumbar subarachnoid space. The patient is maintained in the prone position until a CT scan is performed. Ideally, the contrast medium is concentrated in the intracranial anterior and posterior skull base regions under fluoroscopic guidance by tilting the prone patient head downward on a fluoroscopic tilt table. Alternatively, with the patient lying prone on a stretcher, the patient's hips can be raised above the level of the head for 1-2 minutes to concentrate the contrast medium over the anterior and posterior regions of the skull base. Coronal CT images of 2-3 mm thickness are then obtained through the face and cranium, including all of the paranasal sinuses and the mastoid air cells.

CT cisternographic findings in CSF leak include the concentration of contrast medium in portions of a sinus or within ethmoid or mastoid air cells. Occasionally, a stream of contrast medium is demonstrated at the fistula site.

Digital subtraction radiographic cisternography can be similarly performed with a spinal subarachnoid injection of nonionic iodinated contrast medium. The images may demonstrate a CSF fistula, but this technique is used less frequently than the other cisternographic methods.

Degree of Confidence

The incidence of cerebrospinal fluid (CSF) fistula detection varies from 22-100% in clinical studies. The fistula detection rate is lowest for intermittent CSF leaks. The accuracy of active fistula detection with CT cisternography is 65-85%. In one study of 45 patients, CT of the skull and facial bones with high-resolution, thin-section axial and coronal images had an accuracy of 92%, a sensitivity of 92%, and a specificity of 100% in depicting the presence or absence of CSF fistula.²⁸ Computer-reconstructed coronal images are less accurate and acceptable only until direct CT coronal images can be obtained.

Magnetic Resonance Imaging

Findings

MRI of the brain and spine

Fast spin-echo T2-weighted coronal image of a patient with a spontaneous onset of cerebrospinal fluid rhinorrhea demonstrates an empty-sella configuration.

Spontaneous intracranial hypotension syndrome in a patient with chronic headaches, which began after lumbar puncture. Axial fast spin-echo T2-weighted MRI demonstrates widened extra-axial fluid spaces but no focal extra-axial fluid collection.

Coronal fast spin-echo T2-weighted MRI in the same patient as in Image 17.

Gadolinium-enhanced T1-weighted axial MRI in the same patient as in Image 17 shows diffuse moderate dural thickening with contrast enhancement.

Gadolinium-enhanced, coronal, T1-weighted MRI in the same patient as in Image 17 shows dural and tentorial thickening with contrast enhancement.

Gadolinium-enhanced, T1-weighted axial MRI in the same patient as in Image 17 obtained 2 weeks after a 7-mL extradural blood patch was applied to the midlumbar region. This image shows complete resolution of the previous dural thickening and contrast enhancement. The patient's severe postural headaches were markedly decreased in intensity.

Gadolinium-enhanced, coronal, T1-weighted MRI in the same patient as in Image 17.

In spontaneous intracranial hypotension syndrome (SIHS), brain MRI shows thickening and contrast enhancement in the cranial pachymeninges. Subdural hygroma or hematoma on the cerebral convexities is common. The brain is noted to sink downward in the cranium with development of a pseudo-Chiari I malformation. The cerebral dural venous sinuses may be engorged. The cerebral ventricles may be reduced in size, and the pituitary gland may appear enlarged. The upper cervical epidural veins are congested. All of these changes are reversible with ablation of the cause of CSF leak.

Spinal MRI in patients with SIHS may show some irregularity of the thecal sac due to partial dural collapse. Extradural fluid collections are common in spinal cerebrospinal fluid (CSF) leak. Intense extradural contrast enhancement is noted in congested epidural veins. One or more CSF fistulas may originate from spinal nerve root sleeves in the case of spontaneous spinal CSF leak.

A variety of cisternographic studies may be necessary to localize some spinal CSF fistulas. Spinal MRI findings are potentially reversible after successful ablation of a CSF fistula.

MR cisternography and myelography

Acute posttraumatic cerebrospinal fluid rhinorrhea. This coronal magnetic resonance cisternogram demonstrates a left-sided cerebrospinal fluid leak through the cribriform plate (small arrows), which was clinically suspected. The image also shows a right-sided meningocele (large arrow) protruding through the cribriform plate, which was not suspected but was surgically repaired at the same time as the left cribriform cerebrospinal fluid leak site.

Magnetic resonance cisternogram in the same patient as in Image 4 with cerebrospinal fluid rhinorrhea demonstrates a meningocele extending into the left lateral recess of the sphenoid sinus (arrows).

Axial magnetic resonance cisternogram of the same patient as in Image 4 demonstrates the connection of the meningocele to the middle cranial fossa (arrows). Fluid contained in the meningocele and leaked fluid in the sphenoid sinus outline the meningocele membrane.

Sagittal magnetic resonance cisternogram in the same patient as in Image 4 demonstrates the connection of the meningocele to the middle cranial fossa; this finding facilitated surgical planning.

The high T2 signal from CSF fistula may be difficult to differentiate from that of sinusitis on axial images. A high rate of fistula detection may be possible with imaging in the prone position, but this may be uncomfortable for the patient. Therefore, imaging is usually done with the patient in the supine position. Rapid echo-planar imaging with the patient in the prone position and performing a Valsalva maneuver may allow for limited coronal imaging and increase the accuracy of MR cisternography.

MR cisternography is performed with heavily T2-weighted, fast spin-echo, fat-saturated sequences with thin sections and minimal or no gap. Typical imaging parameters include a repetition time of 10,000 ms, an effective echo time of 200 ms, 4 signals acquired, an echo train length of 16, a matrix of 512 X 192, no phase-wrap option, 3-mm sections interleaved contiguously (0-mm gap), and a 16-cm field of view.

A short repetition time can be used to achieve a result similar to that of the technique above, with slightly faster imaging times. The gray scale is reversed for optimal viewing. Two to three scans of 8 minutes each are needed to cover the required area in each projection. With one method, the average total time for coronal and sagittal imaging is 48 minutes.³³ Most MRI machines offer fat suppression and image gray-scale reversal. Additional hardware or software is not required to perform MR myelography or cisternography.

Sagittal magnetic resonance myelogram demonstrates a traumatic cerebrospinal fluid leak (small arrows) with disruption of the ligamentum flavum posteriorly (large arrow).

Magnetic resonance myelogram in a patient with a brachial plexus injury and pseudomeningoceles (arrows).

Magnetic resonance myelogram demonstrates pseudomeningoceles secondary to a stretch injury of the lumbosacral nerve roots.

Degree of Confidence

In one study, the detection of cerebrospinal fluid (CSF) fistula by MR cisternography had an accuracy of 89%, a sensitivity of 87%, and a specificity of 100%.

False Positives/Negatives

A study of 50 patients without a cerebrospinal fluid (CSF) leak who had an MRI brain scan had a 42% false-positive rate for cribriform plate fistula, which was likely related to a high T2 signal in ethmoid air cells from associated sinusitis and apparent defects in dura or bone from irregular superior ethmoid bone surfaces. 

Ultrasonography

Findings

Diagnostic ultrasound has not been useful in cranial cerebrospinal fluid (CSF) leak. Paraspinal fluid collections can be localized for needle aspiration with ultrasound guidance.

Nuclear Imaging

Findings

Lateral 24-hour cranial scintigraphic image from a nuclear medicine cisternographic study in a patient with clinically evident right-sided cerebrospinal fluid rhinorrhea. Image demonstrates increased tracer accumulation in the nasal region (arrow).

Anterior 48-hour scintigraphic image in the same patient as in Image 1 demonstrates tracer accumulation in the right nasal region. Imaging findings were correlated with both the clinical findings and nasal pledget counts obtained as part of this study.

Nuclear cisternogram obtained at 24 hours in the same patient as in Image 17 demonstrates diffuse epidural accumulation of the tracer in the midlumbar region. This finding is suggestive of a site of cerebrospinal fluid leak.

Head images are acquired 2, 6, 12, and 24 hours after injection of the isotope. Follow-up 48- or 72-hour scans are possible with¹¹¹ In and are useful in the detection of intermittent cerebrospinal fluid (CSF) fluid leaks.

The entire spine is scanned up to 24 hours in cases of spontaneous intracranial hypotension, spinal trauma, or postoperative CSF leaks.³⁶ Cotton pledgets labeled for the placement site are positioned in the nose before the lumbar subarachnoid space injection of the isotope. Pledgets are placed closest to the cribriform plate, in the middle meatus, and in the sphenoethmoidal recess of the right and left nasal cavities. A control pledget for lacrimal secretions is placed under one inferior nasal turbinate.

Pledgets are scanned in a glass tube at intervals of 2-24 hours with the highest count rate indicating a possible leak site. Alternatively, radioactivity of the nasal pledgets is compared with that of known plasma radioactivity.

For otorrhea, 1 cotton pledget is placed in each external auditory canal.

Degree of Confidence

The sensitivity for cerebrospinal fluid (CSF) leaks is in the range of 50-100%. The specificity is almost 100% for contemporary radionuclide cisternography.

Angiography

Findings

Cerebral arteriography is not used in the diagnostic imaging workup to localize the site of a cerebrospinal fluid (CSF) leak. Arterial injury may occur with skull trauma that causes CSF leakage. In this case, diagnostic cerebral and cervical arteriography is necessary.

Intervention

The treatment of cerebrospinal fluid (CSF) leak is primarily surgical. Precise localization of the site of the CSF fistula by using CT, MRI, and cisternographic diagnostic techniques is critical before surgical intervention is done.³⁷ Radiologic interventional procedures are not part of the operative repair of cranial CSF fistulas.

Posttraumatic CSF fistulas persisting beyond 7 days, spontaneous CSF leaks with skull-base defects, increasing pneumocephalus, and meningitis are positive indications for surgical intervention. Extradural endoscopic repair by the otolaryngologist is most helpful in cases needing anterior repair around the cribriform plates. Open craniotomy with intradural repair is necessary for large skull-base defects. The primary goal of surgery is to repair meningeal tears and underlying bone defects.

CSF rhinorrhea or CSF otorrhea

Patients with CSF rhinorrhea or CSF otorrhea are maintained at bedrest in a semisitting Fowler position. They should be instructed to avoid sneezing or coughing, since these actions increase the intracranial pressure and favor persistence of the CSF leak.^38,2

CSF leak related to facial fractures or trauma

Preliminary surgical treatment of facial fractures may result in occlusion of the fistula.

Approximately 85% of all posttraumatic fistulas close spontaneously within 7 days.

Pneumocephalus

Rapidly increasing pneumocephalus may result in acute intracranial hypertension requiring the emergency placement of a cranial bone twist-drill hole and the intracranial insertion of a moderately large-bore needle to evacuate the air.

Spontaneous intracranial hypotension syndrome (SIHS)

Frequently, SIHS and persistent orthostatic headache after lumbar punctures can be successfully treated by radiologists or anesthesiologists using a lumbar epidural blood patch.^39,40 The cause of the SIHS syndrome should be determined as accurately as possible, and the location of the spinal CSF fistula should be demonstrated by means of MR or isotope cisternography.¹ Extradural blood patches are most successful in prolonged or permanent cure of SIHS syndrome and postural headaches when the blood patch is applied at the site of the CSF leak.

Cervical or thoracic spinal CSF fistulas are sometimes effectively treated by using a lumbar blood patch, but successful ablation of the leak occurs less often than with lumbar CSF leak sites.

Occasionally, slow-flow postoperative CSF leaks with lumbar pseudomeningocele have been successfully treated with the aspiration of fluid from the pseudomeningocele and the application of an adjacent extradural blood patch. High-flow CSF fistulas, multiple fistulas, and cervical or thoracic and/or persistent spinal CSF leaks may require surgical meningeal repair.

Sencakova et al⁴¹ used 1-3 (or more) extradural lumbar blood patches. They reported early posttreatment improvement in headaches in 90% of patients, but lasting symptom improvement occurred in only 60-75%.

Bedrest, frequent administration of oral fluids, sedation, and analgesic medication are necessary adjuvant treatments.

Epidural blood patch

A trained and knowledgeable radiologist or anesthesiologist can apply an epidural blood patch. Five to 20 mL of freshly drawn unclotted venous blood has been injected into the epidural space, usually in the lumbar region, in literature reports. The injected blood has been demonstrated to extend for several vertebral segments in the epidural space beyond the site of injection. The patient should be kept at bedrest in a decubitus position for at least 2 hours after the epidural blood patch is applied to achieve the maximal effect from the procedure.

Multimedia

Media file 1: Lateral 24-hour cranial scintigraphic image from a nuclear medicine cisternographic study in a patient with clinically evident right-sided cerebrospinal fluid rhinorrhea. Image demonstrates increased tracer accumulation in the nasal region (arrow).

Media file 2: Anterior 48-hour scintigraphic image in the same patient as in Image 1 demonstrates tracer accumulation in the right nasal region. Imaging findings were correlated with both the clinical findings and nasal pledget counts obtained as part of this study.

Media file 3: Acute posttraumatic cerebrospinal fluid rhinorrhea. This coronal magnetic resonance cisternogram demonstrates a left-sided cerebrospinal fluid leak through the cribriform plate (small arrows), which was clinically suspected. The image also shows a right-sided meningocele (large arrow) protruding through the cribriform plate, which was not suspected but was surgically repaired at the same time as the left cribriform cerebrospinal fluid leak site.

Media file 4: This patient presented with a spontaneous onset of cerebrospinal fluid rhinorrhea 10 years after a head injury. This coronal CT cisternogram was obtained after an intrathecal injection of contrast material (Omnipaque 300, 8 mL) into the lumbar thecal sac and subsequent positioning of the contrast agent in the head. The image demonstrates dense contrast medium layering in the empty sella and contained within the meningocele (arrow).

Media file 5: Axial CT image was obtained with the patient (same patient as in Image 4) in the supine position. Contrast medium has drained out of the meningocele, but a small amount remains in the sphenoid sinus around the meningocele.

Media file 6: Magnetic resonance cisternogram in the same patient as in Image 4 with cerebrospinal fluid rhinorrhea demonstrates a meningocele extending into the left lateral recess of the sphenoid sinus (arrows).

Media file 7: Axial magnetic resonance cisternogram of the same patient as in Image 4 demonstrates the connection of the meningocele to the middle cranial fossa (arrows). Fluid contained in the meningocele and leaked fluid in the sphenoid sinus outline the meningocele membrane.

Media file 8: Sagittal magnetic resonance cisternogram in the same patient as in Image 4 demonstrates the connection of the meningocele to the middle cranial fossa; this finding facilitated surgical planning.

Media file 9: Fast spin-echo T2-weighted coronal image of a patient with a spontaneous onset of cerebrospinal fluid rhinorrhea demonstrates an empty-sella configuration.

Media file 10: Axial CT image of the same patient as in Image 9 demonstrates pneumocephalus in association with the spontaneous cerebrospinal fluid rhinorrhea and a septal bone defect in the left posterior ethmoid air cell.

Media file 11: Coronal CT image of the temporal bone demonstrates a bone defect (small arrows) in the tegmen tympani with a protruding soft-tissue meningoencephalocele (large arrows). This patient had cerebrospinal fluid otorrhea after mastoidectomy.

Media file 12: Coronal fast spin-echo T2-weighted image in the same patient as in Image 11 demonstrates herniation of meninges and brain tissue (arrows) with adjacent cerebrospinal fluid into the postmastoidectomy tegmen tympani defect. This finding is consistent with a meningoencephalocele of the temporal bone.

Media file 13: Artist's rendering of a tegmen tympani bone defect with a herniated meningoencephalocele.

Media file 14: Sagittal magnetic resonance myelogram demonstrates a traumatic cerebrospinal fluid leak (small arrows) with disruption of the ligamentum flavum posteriorly (large arrow).

Media file 15: Magnetic resonance myelogram in a patient with a brachial plexus injury and pseudomeningoceles (arrows).

Media file 16: Magnetic resonance myelogram demonstrates pseudomeningoceles secondary to a stretch injury of the lumbosacral nerve roots.

Media file 17: Spontaneous intracranial hypotension syndrome in a patient with chronic headaches, which began after lumbar puncture. Axial fast spin-echo T2-weighted MRI demonstrates widened extra-axial fluid spaces but no focal extra-axial fluid collection.

Media file 18: Coronal fast spin-echo T2-weighted MRI in the same patient as in Image 17.

Media file 19: Gadolinium-enhanced T1-weighted axial MRI in the same patient as in Image 17 shows diffuse moderate dural thickening with contrast enhancement.

Media file 20: Gadolinium-enhanced, coronal, T1-weighted MRI in the same patient as in Image 17 shows dural and tentorial thickening with contrast enhancement.

Media file 21: Nuclear cisternogram obtained at 24 hours in the same patient as in Image 17 demonstrates diffuse epidural accumulation of the tracer in the midlumbar region. This finding is suggestive of a site of cerebrospinal fluid leak.

Media file 22: Gadolinium-enhanced, T1-weighted axial MRI in the same patient as in Image 17 obtained 2 weeks after a 7-mL extradural blood patch was applied to the midlumbar region. This image shows complete resolution of the previous dural thickening and contrast enhancement. The patient's severe postural headaches were markedly decreased in intensity.

Media file 23: Gadolinium-enhanced, coronal, T1-weighted MRI in the same patient as in Image 17.

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Keywords

cerebrospinal fluid leak, CSF leak, dural tear, dural leak, CSF rhinorrhea, CSF otorrhea, pneumocephalus, spinal CSF leak, intracranial hypotension, spontaneous intracranial hypotension syndrome, SIHS, traumatic CSF fistula, double-ring sign, lumbar extradural blood patch

Contributor Information and Disclosures

Author

Hugh J F Robertson, MD, DMR, FRCPC, FRCR, FACR, Professor Emeritus of Radiology, Professor of Clinical Radiology, Louisiana State University Health Sciences Center, New Orleans; Clinical Professor of Radiology, Tulane University School of Medicine; Active Staff, Department of Radiology, University Hospital
Hugh J F Robertson, MD, DMR, FRCPC, FRCR, FACR is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, American Society of Neuroradiology, American Society of Spine Radiology, Louisiana State Medical Society, Orleans Parish Medical Society, Radiological Society of North America, Royal College of Physicians and Surgeons of Canada, Royal College of Radiologists, and Royal Society of Medicine
Disclosure: Nothing to disclose.

Coauthor(s)

Enrique Palacios, MD, FACR, Professor of Radiology, Neuroradiology, Tulane University Medical Center, New Orleans
Enrique Palacios, MD, FACR is a member of the following medical societies: American College of Radiology, American Medical Association, American Society of Neuroradiology, and Radiological Society of North America
Disclosure: Nothing to disclose.

Michael G D'Antonio, MD, Clinical Associate Professor of Radiology, Louisiana State University Health Sciences Center, New Orleans; Consulting Staff Radiologist, Jefferson Radiology Associates, Inc, West Jefferson Medical Center
Disclosure: Nothing to disclose.

Medical Editor

Lucien M Levy, MD, PhD, Director of Neuroradiology, Professor of Radiology, Department of Radiology, George Washington University Medical Center
Lucien M Levy, MD, PhD is a member of the following medical societies: American Cancer Society, American College of Radiology, American Heart Association, American Medical Association, American Roentgen Ray Society, American Society of Neuroradiology, and Radiological Society of North America
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

C Douglas Phillips, MD, Director of Head and Neck Imaging, Division of Neuroradiology, Weill Medical College of Cornell University/New York Presbyterian Hospital
C Douglas Phillips, MD is a member of the following medical societies: American College of Radiology, American Medical Association, American Society of Head and Neck Radiology, American Society of Neuroradiology, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

L Gill Naul, MD, Professor and Head, Department of Radiology, Texas A&M University College of Medicine; Chair, Department of Radiology, Chief, Section of Magnetic Resonance Imaging, Scott and White Memorial Hospital and Clinic
L Gill Naul, MD is a member of the following medical societies: American College of Radiology, American Medical Association, American Roentgen Ray Society, Radiological Society of North America, and Texas Medical Association
Disclosure: Nothing to disclose.

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