Sphenoid Sinus Cerebrospinal Fluid Leak and Encephalocele Repair (2024)


The surgical management of sphenoid CSF leaks and encephaloceles has evolved significantly over the past century. The major paradigm shifts have included the transition from open to endoscopic approaches and the use of vascularized flap reconstruction techniques. These methods have dramatically improved success rates while reducing morbidity for patients suffering from these disorders.


CSF leak, encephalocele, meningoencephalocele, nasoseptal flap, sphenoid


  • Dandy, in 1926, was the first to report a transcranial technique for the closure of a cerebrospinal fluid (CSF) leak using a fascia lata graft.

  • Open approaches were associated with morbidities, including seizures, memory deficits, and intracranial hemorrhage.

  • Dohlman pioneered an extracranial technique in 1948 with success rates approaching 80%.

  • The first transeptal and fully endonasal approaches were introduced by Hirsch and by Vrabec, respectively.

  • The first endoscopic CSF leak repair was reported by Papay etal. in 1989.

  • The importance of the lateral extension of the sphenoid sinus with respect to CSF rhinorrhea was recognized as early as 1965 by Morley and Wortzman.


  • The majority of the sphenoid bone is formed from the endochondral ossification of five discrete ossification centers beginning in the thirteenth week of development.

  • Incomplete fusion of the greater wing can result in persistence of a lateral craniopharyngeal canal, which was first described by Sternberg in 1888 and may be seen in up to 4% of patients.

  • A role for the Sternberg canal in the pathogenesis of lateral sphenoid CSF leaks is doubtful.

  • The degree of pneumatization may be quite variable and when assessed in the sagittal plane may progress from a relative lack of aeration or “conchal” pattern (5%–10%), through a presellar pattern (25%–30%), and ultimately to a postsellar pattern in which pneumatization extends posteriorly to the level of the clivus (65%).

  • When viewed in the coronal plane, lateral pneumatization into the pterygoid plates is evident in 35.3% of subjects and is bilateral in 17.4%.

  • Tomazic and Stammberger reported a series of five sphenoid CSF leaks, noting that 100% were associated with a patent canal. Conversely, Bernal-Sprekelsen etal. found that among 25 patients with lateral sphenoid leaks, 24 were lateral to the foramen rotundum, which suggests no association with a Sternberg canal.

  • A more accepted etiologic factor in these spontaneous lateral sphenoid lesions is chronic benign intracranial hypertension (BIH).

  • Although lateral sphenoid CSF leaks most commonly occur spontaneously, central leaks tend to result from iatrogenic causes, often in the setting of prior transsphenoidal pituitary surgery.

  • The vidian canal and its associated neurovascular bundle is a key anatomic landmark in the management of these lesions because it may be used to orient the surgeon in both the approach and the localization of critical intracranial structures adjacent to the defect.

  • The vidian nerve can serve as an important landmark in this region because it can reliably be traced to the lateral surface of the anterior genu of the petrous carotid artery.

  • In the midline, the sella contains the pituitary gland, which is surrounded by its associated dural reflections, hypophyseal arteries, optic chiasm, and superior and inferior intercavernous sinuses ( Fig. 27.1 ).

    Sphenoid Sinus Cerebrospinal Fluid Leak and Encephalocele Repair (1)

    Drawing of a coronal cross-section through the sphenoid sinus and associated structures. Note that loss of bone is depicted over the patient’s left cavernous sinus, V2, vidian nerve, and carotid artery as can often present with encephaloceles. a., Artery; n., nerve.

  • The cavernous sinus proper lies immediately lateral to the pituitary fossa and transmits multiple cranial nerves as well as the cavernous (or C4) segment of the internal carotid artery.

  • With extensive pneumatization, the sphenoid may continue laterally to the foramen rotundum beneath the floor of the middle cranial fossa. Inferiorly, this pneumatization pattern may extend into the pterygoid plates inferolateral to the vidian canal.

Preoperative Considerations

Patient History

  • Clinical symptoms may include CSF rhinorrhea (85%), chronic headache (77%), and a history of meningitis (15%). Patients with spontaneous leaks often have increased body mass index with its associated comorbidities, including hypertension, sleep apnea, and BIH.

  • Any history of trauma, inflammatory rhinologic disorders, or prior surgeries (particularly transsphenoidal pituitary procedures) should be elicited.

Clinical Diagnosis

  • Confirmation of CSF rhinorrhea may be performed by testing the fluid for the presence of β 2 -transferrin. Samples collected by the patient will remain stable for β 2 -transferrin testing for up to 1 week at room temperature.

  • Nasal endoscopy may reveal fluid or a meningoencephalocele sac emanating from the sphenoethmoid recess; however, negative examination findings do not preclude the presence of a pathologic process.

  • Pneumatic otoscopy should also be performed in these patients to exclude the presence of middle ear fluid, which raises concern for a primary or synchronous temporal bone CSF leak.

Intrathecal Fluorescein Administration

  • Intrathecal fluorescein administration is a useful adjunct in the management of these lesions. The most common dose is 0.1 mL of 10% sodium fluorescein mixed with 10 mL of the patient’s own CSF or sterile saline and injected over a 10-minute period.

  • Patients must be counseled that this represents an off-label use and that seizures and other neurologic complications have been reported with the use of fluorescein at higher doses.

  • Excitation of the fluorescein with blue light leads to emission of green wavelengths and, when used in conjunction with a blue light–blocking filter, helps to maximize visualization of even small volumes of stained CSF.

  • Placement of a lumbar drain also provides an opportunity for the measurement of opening pressures, which may help to guide postoperative management.

Radiographic Considerations

Computed Tomography

  • Fine-cut, noncontrast, maxillofacial computed tomography (CT) scans should be obtained for any patient with a suspected sphenoid CSF leak or meningoencephalocele.

  • The use of image guidance may be quite helpful; if this is planned, the CT images can be ordered using the available institutional image guidance protocol.

  • The pneumatization pattern and status of the skull base should be assessed in all three planes. The site of the lesion may be indicated by a focal attenuation of the middle fossa bone or frank dehiscence with soft tissue prolapse.

  • The presence of any Onodi cells, laterally based partitions, or dehiscence of the optic nerves or internal carotid arteries should be noted. The location of the vidian canal and foramen rotundum should be identified and the site of abnormalities relative to these structures noted.

  • In the setting of BIH, the CT may reveal several additional stigmata, including an empty sella, arachnoid pitting in the middle cranial fossa, and thinning of the tegmen ( Fig. 27.2 ).

    Sphenoid Sinus Cerebrospinal Fluid Leak and Encephalocele Repair (2)

    Noncontrast coronal computed tomography (CT) images from patients with lateral sphenoid meningoencephaloceles (white arrows). The patient in (A) has a more significantly pneumatized lateral recess than the patient in (B) . Note the significant amount of right middle fossa arachnoid pitting seen in (B) . The relative positions of the optic nerve (O), foramen rotundum (R), and vidian canal (V) are shown.

  • The location of the lesion relative to the foramen rotundum should be determined because this will dictate whether a medial, transethmoid, or transpterygoid approach will be required to gain adequate surgical access.

Magnetic Resonance Imaging

  • Use of T1- (with and without gadolinium) and T2-weighted magnetic resonance imaging (MRI) allows for soft tissue characterization, which helps to differentiate between a CSF leak, encephalocele, and meningoencephalocele.

  • The MRI scan provides additional information on the relationship between the various segments of the internal carotid artery and the site of the defect. Although it is uncommon, the MRI may also provide evidence for any prolapsed intracranial vasculature associated with the defect. If this is a concern, magnetic resonance or interventional angiography should be performed to further characterize these vessels.

  • An empty sella resulting from prolapse of the suprasellar arachnoid cistern into the sellar cavity is also easily seen on a sagittal T1-weighted MRI scan and provides confirmatory evidence for the presence of elevated intracranial pressures.

  • The MRI may be overlaid with the CT data to provide simultaneous intraoperative information on the local bony and soft tissue anatomy.

Adjunctive Imaging

  • The use of angiography, CT/MRI cisternography, and radioactive tracer studies in the workup of these lesions has been previously described. Their use has declined with the increasing popularity of β 2 -transferrin and intrathecal fluorescein confirmatory testing.


  • Adequate exposure of sphenoid CSF leak and meningoencephalocele sites should allow the use of primarily straight instrumentation. The intermittent use of angled endoscopes and instruments with distal angulations may occasionally be required ( Fig. 27.3 ).

    • 0- and 45-degree endoscopes

    • J-curette and ball-tip probe

    • 15-degree diamond drill

    • Straight and curved suction devices

    • Upbiting and downbiting 2-mm Kerrison punches

    • Straight Blakesley forceps

    • Endoscopic clip applier

    • Bipolar cautery

    Sphenoid Sinus Cerebrospinal Fluid Leak and Encephalocele Repair (3)

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Sphenoid Sinus Cerebrospinal Fluid Leak and Encephalocele Repair (2024)


Is CSF leak repair brain surgery? ›

Treatment for a CSF leak of the skull base usually requires surgery. Home to a world-renowned neurological surgery center and state-of-the-art neurological intensive care unit, UT Southwestern has the resources to treat complex skull base conditions.

What is the success rate of CSF leak surgery? ›

Eighty-two of the 95 patients underwent their primary repair surgery at the Mayo Clinic. Seventy-three percent (60/82) of these first repairs were performed successfully. The success rate dropped to 58.6% (17/29) for second repairs and 57.1% (8/14) for third repairs.

How serious is a CSF leak? ›

A CSF leak is a very serious condition, and patients who have tears in their dura with persistent CSF leaks need repair as soon as possible to reduce headache pain and the chance of meningitis.

How do you repair an encephalocele in adults? ›

When necessary, an encephalocele can be treated surgically by gently lifting the brain to repair the underlying defect in the skull base. The specific treatment is determined by the location of the encephalocele or CSF leak, hearing status and other patient-specific factors.

Can you fully recover from a CSF leak? ›

CSF leaks can often cause severe symptoms, but this condition is very treatable, and up to 98% of people with it will recover.

What kind of doctor fixes a CSF leak? ›

Surgical expertise.

Mayo Clinic doctors offer several surgical treatment options for CSF leaks. If you need surgery, it will be performed by a highly trained and experienced neurosurgical expert or an ENT expert.

Can you live a full life with a CSF leak? ›

Prognosis for spontaneous spinal CSF leaks

These patients do well overall, although some may require several procedures. Some patients with spontaneous leaks have symptoms that resolve spontaneously in a matter of hours, days, or weeks without ever seeking medical care.

Is a CSF leak a disability? ›

Spinal cerebrospinal fluid (CSF) leak is a debilitating, disabling condition that isn't always visible from the outside—or even sometimes from the inside, despite sophisticated medical imaging.

What happens if you don't fix a CSF leak? ›

A leak can be detrimental to brain blood supply and function and can increase the risk of direct trauma to brain parenchyma due to loss of fluid cushion. Open communication of the subarachnoid space with CSF leak also presents a pathway for life-threatening CNS infection, including meningitis.

What is the mortality rate of CSF leak? ›

Mortality for patients with CSF leaks was 22.8% versus 5.1% among patients without leaks, although there was no control for confounding variables. The incidence of infection in this study was 49.5% versus 4.6% in the 1,032 casualties without CSF leaks.

What to expect after CSF leak surgery? ›

Sleep with your head slightly elevated for 7 days. Stay in a bed or chair with your head up during the day for 7 days. You may go to the restroom. No heavy lifting, bending over, or straining for 30 days.

When is CSF leak an emergency? ›

If a CSF leak is suspected, you should see a physician as soon as possible. If symptoms of meningitis (high fever, light sensitivity, neck stiffness) are suspected, you should go to the emergency room.

What is the survival rate for encephalocele surgery? ›

Encephaloceles may be associated with brain malformations that can have an effect on the prognosis. The location of the encephalocele greatly affects the prognosis. Those located in the front have a 100 percent survival rate, while those located in the back have a 55 percent survival rate.

Can an ENT see a CSF leak? ›

The most typical tests used for diagnosing CSF leak are done through an examination from an ear, nose and throat (ENT) specialist. The ENT will most likely use nasal endoscopy, CT and MRI imaging techniques, as well as chemical tests of the liquid that is escaping (beta 2 transferrin test).

When is the timing of encephalocele repair? ›

Encephalocele is defined as herniation of cranial contents beyond the normal confines of the skull through a defect in the calvarium either along the midline or at the base of skull. These anomalies should be repaired in the first few months of life to prevent neurological deficits and facial disfigurement.

What is the name of the surgery for CSF leak repair? ›

This leak can be repaired endoscopically using ones own tissue from inside the nose or with biocompatible materials. Endoscopic Endonasal surgery has a high success rate and is the gold standard of intervention in such situations.

Can you have a CSF leak without surgery? ›

If it is a small leak, it may resolve on its own, while larger leaks may require surgical intervention. Conservative treatment for a CSF leak typically includes bed rest and increased oral fluids. Other treatments, such as a lumbar epidural blood patch, may be recommended if the leak persists.

What is the procedure to remove CSF from the brain? ›

A shunt is a thin tube that drains away the extra CSF from the ventricles of the brain. The shunt drains the CSF to other parts of the body, where it is absorbed. Shunts are usually plastic and small, about 0.3cm (3mm) across. They have valves so that fluid can flow down from the brain but not back the other way.

Do you need surgery for CSF? ›

Many CSF leaks heal on their own, but others require surgical repair.


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