eMedicine Specialties > Otolaryngology and Facial Plastic Surgery > Nasal & Sinus Diseases

CSF Rhinorrhea

Kevin C Welch, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, Loyola University Medical Center
James Stankiewicz, MD, Professor, Chair, Program Director, Department of Otolaryngology-Head and Neck Surgery, Loyola University Chicago School of Medicine

Updated: Sep 28, 2009

Introduction

Disruption of the barriers between the sinonasal cavity and the anterior and middle cranial fossae can lead to the discharge of cerebrospinal fluid (CSF) into the nasal cavity. The resulting communication with the central nervous system can lead to a multitude of infectious complications that impart significant morbidity and potentially disastrous long-term deficits for the patients involved.

This article discusses current concepts in the etiology, diagnosis, and treatment of CSF rhinorrhea, as well as long-term management of patients following successful treatment.

An axial CT of a patient with a spontaneous CSF leak reveals a defect in the posterior table of the left frontal sinus.

History Of The Procedure

The first published report of the surgical repair of CSF rhinorrhea comes from Dandy in 1926 who performed a frontal craniotomy to repair a defect. Various reports by Dohlman (1948), Hirsch (1952), and Hallberg (1964) all demonstrate repair of skull base defects through various external approaches. In 1981, Wigand reported on the use of the endoscope to assist with the repair of a skull base defect. In the last 20 years, endoscopic repair of skull base defects has become the preferred method of addressing CSF rhinorrhea and is successful in 90-95% of cases.

Problem

The underlying defect responsible for CSF leaks, regardless of the etiology, is the same: disruption in the arachnoid and dura mater coupled with an osseous defect and a CSF pressure gradient that is continuously or intermittently greater than the tensile strength of the disrupted tissue.

Frequency

See Etiology.

Etiology

Cerebrospinal fluid (CSF) consists of a mixture of water, electrolytes (Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl^-, and HCO3^-), glucose (60-80% of blood glucose), amino acids and various proteins (22-38 mg/dL). Cerebrospinal fluid is colorless, clear, and typically devoid of cells such as polymorphonuclear cells and mononuclear cells (<5/mm3).

The primary site of CSF production is the choroid plexus, which is responsible for 50-80% of its daily production. Other sites of production include the ependymal surface layer (up to 30%) and capillary ultrafiltration (up to 20%). Cerebrospinal fluid (CSF) represents the end product of the ultrafiltration of plasma across epithelial cells in the choroid plexus lining the ventricles of the brain. A basal layer Na⁺/K⁺ ATPase is responsible for actively transporting Na⁺ into epithelial cells, after which water follows across this gradient. Carbonic anhydrase catalyzes the formation of bicarbonate inside the epithelial cell. Another Na⁺/K⁺ ATPase lining the ventricular side of the epithelium extrudes Na⁺ into the ventricle, with water following across this ionic gradient. The resulting fluid is termed cerebrospinal fluid (CSF).

Cerebrospinal fluid (CSF) is produced at a rate of approximately 20 mL/hr for a total of approximately 500 mL daily. At any given time, approximately 90-150 mL of CSF is circulating throughout the CNS. Cerebrospinal fluid (CSF) produced at the choroid plexus typically circulates from the lateral ventricles to the third ventricle via the aqueduct of Sylvius. From the third ventricle, the fluid circulates into the forth ventricle and out into the subarachnoid space via the foramina of Magendie and Luschka. After circulating through the subarachnoid space, CSF is reabsorbed via the arachnoid villi.

Circulation of CSF is maintained by the hydrostatic differences between its rate production and its rate of absorption. Normal CSF pressure is approximately 10-15 mm Hg, and elevated pressure constitutes an intracranial pressure (ICP) greater than 20 mm Hg.

In the adult patient, broadly classifying CSF rhinorrhea into the following 2 categories is helpful: Spontaneous CSF rhinorrhea and CSF rhinorrhea that is secondary to a suspected or known skull base defect. Cerebrospinal fluid leaks that are secondary in nature fall into the categories of trauma, iatrogenic, and tumor-related.

Nonsurgical trauma

Penetrating and closed-head trauma cause 90% of all cases of CSF rhinorrhea. Cerebrospinal fluid rhinorrhea following a traumatic injury is classified as immediate (within 48 h) or delayed. Of patients with delayed CSF leaks, 95% present within 3 months after the insult. Most patients with CSF leaks secondary to accidental trauma (eg, motor vehicle accidents) present immediately. In contrast, only 50% of patients with iatrogenic CSF leaks present within the first week.

Surgical trauma

Surgical trauma usually occurs during endoscopic sinus surgery or during neurosurgical procedures. In patients who are undergoing endoscopic sinus surgery, the site of injury is most frequently the lateral cribriform lamella, where the bone of the anterior skull base is thinnest. Other common locations include the posterior fovea ethmoidalis and the posterior aspect of the frontal recess. Skull base injuries vary from simple cracks in the bony architecture to large (>1 cm) defects with disruption of the dura and potentially brain parenchyma. Neurosurgical procedures that result in CSF rhinorrhea include transsphenoidal hypophysectomy and the endoscopic resection of pituitary and suprasellar masses.

Tumor-related CSF rhinorrhea

The growth of benign tumors does not commonly result in CSF rhinorrhea. However, aggressive lesions (such as inverted papilloma) and malignant neoplasms can erode or invade the bone of the anterior cranial fossa. The enzymatic breakdown or destruction of the bony architecture results in inflammation of the dura and potential violation of the dura by the tumor. If this does not present with CSF rhinorrhea, very frequently the resection of these tumors results in immediate CSF rhinorrhea that is typically repaired at the time of the resection, either transcranially or endoscopically.

Congenital

Defects in the closure of the anterior neuropore can result in the herniation of central nervous tissue through anterior cranial fossa skull base defects. Typically, these present through the fonticulus frontalis or the foramen cecum. Meningoencephaloceles typically present in childhood as external nasal masses or intranasal masses seen on examination.

Spontaneous CSF rhinorrhea

Spontaneous CSF rhinorrhea occurs in patients without antecedent causes already discussed. This terminology seems to imply that spontaneous CSF leaks are idiopathic in nature; however, recent evidence has led us to realize that spontaneous CSF rhinorrhea is in reality secondary to an intracranial process, namely elevated intracranial pressure (ICP). The causes of elevated ICP can be multifactorial; nevertheless, once elevated ICP develops, the pressure exerted on areas of the anterior skull base (eg, cribriform, lateral recess of the sphenoid sinus) result in remodeling and thinning of the bone. Ultimately, the bone is weakened until a defect is formed. At this point, the dura begins to herniate through the defect (meningocele). If a defect is large, brain parenchyma may be herniated as well (encephalocele).

Pathophysiology

In cases of an immediate leak, a dural tear and a bony defect or fracture has occurred. Possible causes of a delayed traumatic leak are a previously intact dural layer that has slowly become herniated through a bony defect, finally tearing the dura and causing the leak. According to another theory, the tear and bony defect are present from the time of the original injury, but the leak occurs only after the masking hematoma dissolves.

Spontaneous CSF rhinorrhea usually manifests in adulthood, coinciding with a developmental rise in CSF pressures with maturity. The dura of the anterior cranial base is subject to wide variations in CSF pressure because of several factors, including normal arterial and respiratory fluctuations. Other stresses on the dura include Valsalvalike actions during nose blowing. This stress can lead to dural injury in areas of abnormalities of the bony floor.

Increased intracranial pressure is not necessary for nontraumatic CSF leaks to occur. Theories for primary nontraumatic CSF leaks include focal atrophy, rupture of arachnoid projections that accompany the fibers of the olfactory nerve, and persistence of an embryonic olfactory lumen.

Presentation

History

A thorough history is the first step toward accurate diagnosis. The typical history of a CSF leak is that of clear, watery discharge, usually unilateral. Diagnosis is made more easily in patients with recent trauma or surgery than in others. Delayed fistulas are difficult to diagnose and can occur years after the trauma or operation. These cases often lead to a misdiagnosis of allergic and vasomotor rhinitis. On occasion, the patient has a history of headache relieved by drainage of CSF. Drainage may be intermittent as the fluid accumulates in 1 of the paranasal sinuses and drains externally with changes in head position (ie, reservoir sign).

A history of headache and visual disturbances suggests increased intracranial pressure. Sometimes, associated symptoms can assist in localizing the leak. For example, anosmia (present in 60% of individuals with posttraumatic rhinorrhea), indicates an injury in the olfactory area and anterior fossa, especially when it is unilateral. Interference with function of the optic nerve suggests a lesion in the region of tuberculum sellae, sphenoid sinus, or posterior ethmoid cells. Patients with recurrent meningitis, especially pneumococcal meningitis, should be evaluated for a defect that exposes the intracranial space to the upper airway regardless of the presence or absence of CSF rhinorrhea.

Physical examination

Physical examination should include complete rhinologic (including endoscopic), otologic, head and neck, and neurologic evaluations. Endoscopy may reveal pathology, such as an encephalocele or meningocele. Drainage of CSF in some cases may often be elicited on endoscopy by having the patient perform a Valsalva maneuver or by compressing both jugular veins (Queckenstedt-Stookey test). Often physical examination is unrevealing, especially in patients with intermittent CSF rhinorrhea.

In patients with head trauma, a mixture of blood and CSF may make the diagnosis difficult. CSF separates from blood when it is placed on filter paper, and it produces a clinically detectable sign: the ring sign, double-ring sign, or halo sign. However, the presence of a ring sign is not exclusive to CSF and can lead to false-positive results. In contrast to unilateral rhinorrhea, bilateral rhinorrhea gives no clue of the laterality of the defect. However, even in this situation, exceptions can occur. Paradoxical rhinorrhea occurs when midline structures that act as separating barriers (eg, crista galli, vomer) are dislocated. This dislocation allows CSF to flow to the opposite side and manifest at the contralateral naris. The clinical findings most frequently associated with CSF rhinorrhea are meningitis (30%) and pneumocephalus (30%).

Indications

Unless medical or surgical contraindications exist, surgical repair is recommended in all patients with spontaneous or iatrogenic CSF rhinorrhea in order to prevent ascending meningitis.

In patients with nonsurgical trauma, waiting a period of 7-10 days to allow conservative measures (bed rest, stool softeners, and lumbar drainage) to assist with spontaneous closure of the traumatic defect is reasonable. However, if CSF rhinorrhea persists beyond this point, or if a large skull base defect is observed at the time of injury, surgical repair is warranted.

If the operating surgeon has experience with the repair of skull base injuries, a repair should be performed at the time of an iatrogenic surgical injury to prevent long-term infectious complications.

Relevant Anatomy

The most common anatomic sites of cerebrospinal fluid (CSF) leaks are the areas of congenital weakness of the anterior cranial fossa and areas related to the type of surgery performed. According to data from 53 patients with different causes of CSF rhinorrhea, 39% of leaks occurred in the region of the cribriform plate and air cells of the ethmoid sinus; in 15% of leaks, the fistula extended to the frontal sinus; and in another 15%, the leak was in the area of the sella turcica and sphenoid sinus.¹

Common sites of injury secondary to endoscopic sinus surgery include the lateral lamella of the cribriform plate and the posterior ethmoid roof near the anterior and medial sphenoid wall. Rarely, the leak can originate in the middle or posterior cranial fossa and can reach the nasal cavity by way of the middle ear and eustachian tube.

Contraindications

Surgical repair of skull base defects resulting in cerebrospinal fluid (CSF) rhinorrhea is contraindicated in any patient who is not medically stable to undergo a general anesthetic or comply with postoperative care.

The management of CSF rhinorrhea depends on the cause, location, and severity of the leak. When trauma is the cause, the interval between trauma and leak is important. The natural history of CSF leak depends on the etiology.

Traumatic leaks often stop spontaneously. The leakage stops within 1 week in 70% of patients, within 3 months in 20-30%, and within 6 months in most patients; leakage rarely recurs. The opposite is true for nontraumatic leaks; only one third stop spontaneously, and they tend to persist for several years, with intermittent leakage.

Workup

Laboratory Studies

• Glucose determination
  • A rapid but highly unreliable test is glucose-content determination with the use of glucose oxidase paper. This method of detecting CSF rhinorrhea is not recommended as a screening or confirming lab test to detect the presence of CSF in the nasal cavity for the following reasons:
    • Reducing substances present in the lacrimal-gland secretions and nasal mucus may cause false-positive results.
    • Glucose, at a concentration of 5 mg/dL, can lead to a positive result with this test.
  • Active meningitis can lower the glucose level in the CSF and may lead to false-negative readings.
  • This test is not specific for the side or site of leak.
• Beta-trace protein
  • Also known as prostaglandin D synthase, this protein is synthesized primarily in arachnoid cells, oligodendrocytes, and the choroids plexus within the CNS.
  • Beta-trace protein is also present in the human testes, heart, and serum, making it not specific for CSF.
  • It is altered by the presence of renal failure, multiple sclerosis, cerebral infarction, and certain CNS tumors.
  • This test has been used to diagnose CSF rhinorrhea in multiple studies, with a sensitivity of 92% and specificity of 100%.
  • This test is not specific for side or site of leak and can be difficult to collect if the leak is intermittent.
• Beta-2 transferrin
  • Beta2-transferrin is produced by neuraminidase activity within the central nervous system; therefore, B-2 transferrin is located only within the CSF, perilymph, and aqueous humor.
  • The assay has a high sensitivity and specificity, it is performed rapidly, and it is noninvasive.
  • A minimum of 0.5 mL of fluid is necessary for electrophoresis, but difficulties in collection of this fluid have been noted, especially in intermittent, low-volume leaks.
  • Beta-2 transferrin is stable at room temperature for approximately 4 hours; therefore, immediate refrigeration following collection is recommended as the protein will remain stable for up to 3 days. Specimens should not be frozen.
  • Not specific for side or site of leak; can be difficult to collect if leak is intermittent in nature.
  • This is currently the recommended single lab test for identifying the presence of CSF in sinonasal fluid.

Imaging Studies

• Computed tomography (CT) scanning
  • High-resolution CT scanning is the imaging modality of choice for identifying a skull base defect associated with CSF rhinorrhea.
  • CT scans may demonstrate skull base defects resulting from accidental or iatrogenic trauma, an underlying anatomic or developmental abnormality, or a lesion such as a neoplasm.
  • CT scans should be performed in the axial plane with 1 mm slice thickness and reformatted into coronal and sagittal planes. The evaluation of congenital defects or spontaneous defects may be aided by 3-dimensional reconstruction of the bone to permit in-depth analysis of the floor of the anterior or middle cranial fossa.
  • Pneumocephalus on a scan suggests a dural tear.
  • Deviated crista galli is a radiologic sign in patients presenting with primary CSF rhinorrhea; this finding supports a congenital bony dehiscence as the etiologic basis for this condition.
  • In some circumstances, an air-fluid level is present in one or more of the sinuses. This is not diagnostic of CSF and may be the result of acute or chronic inflammation.
  • High resolution CT imaging may reveal defects in the skull base that do not leak or are not sites of active leaking, making the diagnosis more difficult.
    
    

    

    An axial CT of a patient with a spontaneous CSF leak reveals a defect in the posterior table of the left frontal sinus.

    
    
• Magnetic resonance imaging (MRI)
  • Unlike CT imaging, MRI does not delineate well bony defects within the anterior or middle cranial fossa.
  • Unlike CT imaging, MR imaging is more costly and more time consuming. In many instances, the injection of a contrast agent may be necessary.
  • Like CT imaging, MR imaging may not be localizing.
  • MRI typically is not recommended as a first line imaging modality in the evaluation of CSF rhinorrhea unless an encephalocele is demonstrated on examination or suspected.
• CT cisternography
  • The diagnostic yield of CT scan can be improved by injecting intrathecal contrast.
  • The advantages CT cisternography has over conventional CT imaging include more accurate localization and the utility of having to perform only one study. Additionally, the frontal sinus and sphenoid sinus may act as reservoirs for CSF fluid.
  • CT cisternography depicts the precise location of CSF rhinorrhea in most patients with active leaks.
  • The disadvantages of CT cisternography include the fact that patients with intermittent CSF rhinorrhea may have false negative CT cisternograms and may miss cribriform or ethmoid sinus defects.
  • This procedure has a low morbidity rate, although nausea, headaches, and acute organic psychosyndromes have been reported.
  • CT cisternography is an invasive procedure.
• MR cisternography
  • Pulse sequences performed during MR imaging can be designed so as to enhance the probability of detecting CSF within the sinonasal cavity.
  • T2-weighted imaging can be used to detect the presence of CSF in the sinonasal cavity without the injection of intrathecal contrast.
  • As with CT cisternography, false negative studies may result when CSF rhinorrhea is intermittent.
• Nuclear medicine studies
  • Radioactive isotopes can be introduced into the CSF by means of lumbar or suboccipital puncture. The distribution of these agents then can be determined by using serial scanning or scintiphotography. Another option is to introduce nasal pledgets in various high-risk areas. These pledgets then can be analyzed for the presence of the tracer.
  • Different tracers, including radioactive iodine-131, radioactive iodinated serum albumin (RISA), ytterbium-169, diethylenetriamine pentaacetic acid (DTPA), indium-111 DTPA, technetium-99m human serum albumin, and^99m Tc pertechnetate, can be used. Despite their relative safety, studies based on these tracers have several limitations, as follows: (1) They do not help in precisely identifying the location of the leak. (2) The isotope is absorbed into the circulatory system and can contaminate extracranial tissue. (3) Patient positioning can cause distal pledgets to incorrectly take up the isotope. (4) Readings of radioactivity should be high to determine a true leak; borderline readings are not reliable. False-positive results are present in as many as 33% patients.

For further information, please see the eMedicine topic Cerebrospinal Fluid, Leak in the Radiology section.

Diagnostic Procedures

The injection of intrathecal fluorescein has been used to diagnose and localize the site(s) of CSF rhinorrhea.²

• The US Food and Drug Administration has not approved the use of intrathecal fluorescein for the diagnosis or treatment of CSF rhinorrhea.
• Precisely 0.1 mL of 10% nonophthalmic solution is diluted in 10 mL of CSF and reinjected into the subarachnoid space over a period of 10 minutes. The use of this dilution and techniques helps to minimize central complications (such as seizures) that have been reported in the past with intrathecal fluorescein.
• Nasal endoscopy is performed approximately 30 minutes after an intrathecal injection of fluorescein. In many instances, the surgeon may use this time to perform the initial dissection of the sinuses that would otherwise be performed to gain access to the defect.
• In most instances, fluorescein is directly observable within the sinonasal cavity using standard xenon light sources used during endoscopic sinus surgery. However, small defects may leak only a minute amount of fluorescein, and this may be difficult to observe.
• The peak absorption range of fluorescein is 494 nm. A blue-light filter (440-490 nm wavelength) can help enhance the visualization of fluorescein, especially in circumstances when fluorescein may be filling an encephalocele or areas of thin bone that could not otherwise be observed with standard xenon light sources.
  
  

  

  After intrathecal fluorescein is administered, an exposed frontal recess encephalocele is seen.

  
  

Treatment

Medical Therapy

Conservative management

Conservative treatment has been advocated only in cases of immediate-onset CSF rhinorrhea following nonsurgical trauma. Conservative management consists of a 7-10 day trial of bed rest with the patient in a head-up position. A head-of-bed position at 15-30° is sufficient to reduce the CSF pressure at the basal cisterns. Coughing, sneezing, nose blowing, and heavy lifting should be avoided as much as possible. Stool softeners should be deployed to decrease the strain and increased ICP associated with bowel movements.

A subarachnoid lumbar drain may be placed to drain approximately 10 mL of CSF per hour. Continuous drainage is recommended over intermittent drainage to avoid spikes in CSF pressure. The long-term consequences of a persistent defect in the anterior cranial fossa dissuade many physicians from deploying this method of treatment (see below).

Antibiotics

The question of the use of prophylactic antibiotics in patients with CSF rhinorrhea stems from the reasonable assumption that a communication between a sterile environment (intracranial vault) and a nonsterile environment (sinonasal cavity) will ultimately result in infection of the sterile compartment. However, this assumption has not been easy to study and even harder to prove.

The routine use of prophylactic antibiotics in the case of nonsurgical traumatic CSF rhinorrhea has been studied in the past with mixed results. A study of 27 patients comparing conservative treatment and transcranial repair revealed that the rates of ascending meningitis in patients treated conservatively were as high as 29%. Nevertheless, that same study showed a 40% rate of meningitis in patients treated via the transcranial route. This was not a statistically significant difference from the rate of 29% in conservatively treated patients. However, 2 recent meta-analyses of patients presenting with nonsurgical traumatic CSF leaks revealed no difference in the rates of ascending meningitis in patients treated with prophylactic antibiotics compared with patients treated with conservative measures alone.

The use of prophylactic antibiotics in patients incurring skull base injuries during endoscopic sinus surgery has not been studied in a randomized controlled fashion. However, administering antibiotics in this setting is reasonable because the skull base injury occurred during surgery for chronic inflammatory/infectious sinusitis and implantation of bacteria into the sterile compartment may have occurred.

Diuretics

Acetazolamide is a nonbacteriocidal sulfonamide that is used primarily as a diuretic. Acetazolamide can be a useful adjunct in the treatment of patients with spontaneous CSF rhinorrhea associated with elevated intracranial pressure. Acetazolamide inhibits the reversible conversion of water and CO₂ to bicarbonate and hydrogen ions.

The relative deficiency of hydrogen ions within epithelial cells results in decreased Na/K ATPase activity, which results in decreased efflux of water into the CSF. Ultimately, this reduces the volume of CSF. The side effects of acetazolamide include weight loss, diarrhea, nausea, metabolic acidosis, polyuria, and paresthesias, any of which may result in the cessation of therapy. When deployed, metabolic profiles should be monitored on a regular basis to ascertain the effect on serum electrolytes.

Surgical Therapy

Surgical options for repair of CSF leaks arising from the anterior skull base can be divided into intracranial and extracranial approaches.

Intracranial repair

Intracranial repair was frequently undertaken (and is still used in select cases) for the routine repair of anterior cranial fossa CSF leaks until the latter part of the 20^th century. These leaks typically were approached via a frontal craniotomy. In rare situations, a middle fossa craniotomy or posterior fossa craniotomy was required for leaks arising in those areas. Different repair techniques have been used, including the use of free or pedicled periosteal or dural flaps, muscle plugs, mobilized portions of the falx cerebri, fascia grafts, and flaps in conjunction with fibrin glue. Leaks arising from the sphenoid sinus are difficult to reach by means of an intracranial approach.

Advantages of the intracranial approach include the ability to inspect the adjacent cerebral cortex, the ability to directly visualize the dural defect, and the ability to seal a leak in the presence of increased ICP with a larger graft. When preoperative localization attempts fail to reveal the site of a leak, intracranial approach with blind repair has been successful. In these situations, the cribriform and the sphenoid area, if necessary, are covered with the repair material.

Disadvantages of the intracranial approach include increased morbidity, increased risk of permanent anosmia, trauma related to brain retraction (hematoma, cognitive dysfunction, seizures, edema, hemorrhage), and prolonged hospital stays. Failure rates for this approach are 40% for the first attempt and 10% overall.

Extracranial repair

Extracranial repair can be divided into external approaches and endoscopic techniques.

• External approach
  • Defects in the posterior table of the frontal sinus may be approached externally via a coronal incision and osteoplastic flap. The osteoplastic flap provides the surgeon with a view of the entire posterior table of the frontal sinus and is especially useful for defects more than 2 cm above the floor and lateral to the lamina papyracea. In select cases, these defects may also be approached with a simpler eyebrow incision and an extended trephination of the frontal sinus in combination with an extended endoscopic frontal sinusotomy. Care must be taken to avoid unnecessary trauma to the surrounding mucosa and the frontal recess entirely.
  • External approaches to the skull base can also be obtained through various incisions or through nasal approaches for access to the ethmoid sinuses and sphenoid sinus. These include external ethmoidectomy, transethmoidal sphenoidotomy, transseptal sphenoidotomy, and the transantral approach to the skull base. These procedures are infrequently chosen now given the superiority of the endoscopic approach.
• Endoscopic approach
  • Compared with external techniques, endoscopic techniques have several advantages, including better field visualization with enhanced illumination and magnified-angle visualization. Other advantages include the ability to clean the mucosa off the adjacent bone without increasing the size of the defect and accurate positioning of the graft. Multiple studies demonstrate a 90-95% success rate with closure of skull base defects using the endoscopic approach.
  • The repair begins with the placement of a subarachnoid drain and the administration of fluorescein. Fluorescein is not approved by the FDA for the diagnosis and treatment of CSF leaks. Precisely 0.1 mL of 10% fluorescein is mixed with 10 mL of autologous CSF or bacteriostatic saline and injected through a subarachnoid drain over a period of 10 minutes. The authors have found that injecting this mixture over 10 minutes has resulted in significantly fewer adverse events (eg, seizures) when compared with early reports in the literature.

As previously mentioned, the role of antibiotic prophylaxis has not been studied in a controlled fashion for iatrogenic and spontaneous CSF rhinorrhea. However, the authors believe that previously published rates of ascending meningitis in untreated CSF leaks is enough to warrant the administration of intravenous antibiotics at the time of the surgical repair.

Decongestion of the nasal cavity with topical oxymetazoline or 4% cocaine solution is recommended in order to maximize endoscopic visualization. Injection of 1% lidocaine with 1:100,000 epinephrine at the root of the middle turbinate and region of the sphenopalatine artery (either transoral or transnasal) helps vasoconstrict blood vessels in these areas and helps to minimize bleeding. The use of intravenous anesthesia with propofol and remifentanil has also been demonstrated to reduce intraoperative blood loss when compared with inhalational anesthesia.

Wide exposure of the defect and any encephalocele is recommended prior to resecting an encephalocele and repairing a skull base injury. This includes performing an adequate maxillary antrostomy, ethmoidectomy, sphenoidotomy, and, if necessary, a frontal sinusotomy. Widely opening the paranasal sinuses can help with visualization and can help prevent iatrogenic sinusitis postoperatively when the nasal cavity is packed with graft material.

For CSF leaks and encephaloceles occurring in the region of the cribriform plate, removing the middle turbinate and sparing this structure for use as grafting material is often helpful. Access to the lateral recess of the sphenoid sinus may require ligation of the sphenopalatine artery, dissection of the vidian nerve, and approach via the pterygomaxillary fossa. Large defects in the sphenoid sinus may require a posterior septectomy for exposure.

A small cribriform plate encephalocele is observed only after removing the middle turbinate.

A defect in the skull base is measured with a sterile ruler.

Septal bone is used as an underlay graft in the repair of this skull base defect in a patient with a spontaneous leak and encephalocele. (Defect measured approximately 7mm.)

Wound closure and postoperative care

Grafts should be anchored to the skull base with the administration of fibrin sealant. The amount of fibrin sealant should be sufficient to anchor the graft yet not obstruct adjacent sinuses or prevent remucosalization of the graft site. The repair is reinforced with gelfoam and nonabsorbable packing to help apply pressure to the graft site.

Preoperative Details

Preoperative CT scans in the coronal plane should be thoroughly reviewed prior to the start of the case. A review of critical anatomy should be performed. This includes identifying areas of the skull base prone to injury and spontaneous defects: posterior table of the frontal sinus near the frontal recess, the cribriform plate and fovea ethmoidalis, the planum sphenoidale, and, if present, the lateral recess of the sphenoid sinus.

When available, the use of stereotactic image-guided equipment can be calibrated and used intraoperatively to improve navigation and localization during surgery.

Triplanar images help to identify and conceptualize the location of this lateral recess encephalocele.

Intraoperative Details

At the end of the surgical case, antiemetics should be administered, and the stomach should be aspirated of blood and fluid to help minimize postoperative nausea and vomiting. The head of bed should be elevated to 15° and the lumbar drain opened to continuously drain 5-10 mL of CSF per hour. If safe, a deep extubation should be attempted and nasal positive pressure is to be avoided.

Postoperative Details

If the repair of the skull base immediately followed an inadvertent injury to the skull base during routine surgery (eg, endoscopic sinus surgery), a head CT scan should be obtained to ascertain the extent of injury to the brain.

Lumbar drainage is performed at 5-10 mL per hour for 48 hours. In patients with known or suspected elevated ICP, the drain is clamped after 48 hours for 6 hours. At this point, an opening pressure is measured. If it is above 20 mm Hg, adjunctive medical therapy is advised (see Diuretics in the Treatment section).

Follow-up

Nonabsorbable packing should be removed 7-10 days after the procedure is performed. Regular endoscopic inspection with minimal debridement of the surgical site should be performed over the long term to identify recurrence of disease.

If the patient is found to have elevated intracranial pressure, the help of a multidisciplinary approach involving an internist, ophthalmologist, and neurologist is invaluable for monitoring patient compliance with adjunctive medication as well as for receiving necessary comprehensive care.

Complications

Knowing the natural course of this condition is important before one examines the results of the various interventions. Meningitis is the most frequent and severe complication of a CSF leak; Streptococcus pneumoniae and Haemophilus influenzae are the most common pathogens. The risk of meningitis during the first 3 weeks after trauma is estimated to be 10%. The rate is 40% in nontraumatic rhinorrhea.

Meningitis caused by a persistent CSF leak is associated with a high mortality rate. Because of the relatively low rate of spontaneous closure, a conservative approach for these indications is not recommended. Spontaneous closure rates vary with the etiology; the recurrence rate after spontaneous closure was 7% in 1 study. The surgical mortality rate is 1-3% for intracranial procedures and is negligible for external procedures. The morbidity for intracranial approaches is clinically significant, with anosmia being the most common complication (10-25% of patients).

Outcome and Prognosis

See individual surgical techniques in Surgical therapy.

Future and Controversies

CSF rhinorrhea can occur as a result of craniofacial injury, iatrogenic surgical trauma, or spontaneous causes. Several diagnostic tools are available to aid in diagnosis. In the case of early-onset traumatic fistula, a conservative approach can be used. Other causes require a more aggressive intervention. Endoscopic and external techniques have replaced invasive craniotomy. Because of these techniques, the otolaryngologist plays a key role in diagnosing and managing this problem.

With the growing popularity of computer-assisted, image-guided surgical techniques, the ability to precisely locate areas of CSF leakage is enhanced. This advance may improve the accuracy and precision of closing the defects, with a resulting increase in success rates. In addition, the use of synthetic graft material to repair these defects is another option that has recently become available.

Multimedia

Media file 1: An axial CT of a patient with a spontaneous CSF leak reveals a defect in the posterior table of the left frontal sinus.

Media file 2: After intrathecal fluorescein is administered, an exposed frontal recess encephalocele is seen.

Media file 3: A defect in the skull base is measured with a sterile ruler.

Media file 4: A small cribriform plate encephalocele is observed only after removing the middle turbinate.

Media file 5: Septal bone is used as an underlay graft in the repair of this skull base defect in a patient with a spontaneous leak and encephalocele. (Defect measured approximately 7mm.)

Media file 6: Triplanar images help to identify and conceptualize the location of this lateral recess encephalocele.

References

1. Lindstrom DR, Toohill RJ, Loehrl TA, Smith TL. Management of cerebrospinal fluid rhinorrhea: the Medical College of Wisconsin experience. Laryngoscope. Jun 2004;114(6):969-74. [Medline].

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Keywords

CSF, rhinorrhea, CSF rhinorrhea, cerebrospinal fluid, cerebrospinal fluid rhinorrhea, CSF leak, cerebrospinal fluid leak, traumatic CSF leak, nontraumatic CSF leak, primary nontraumatic CSF leak, secondary nontraumatic CSF leak, secondary nontraumatic CSF rhinorrhea, spontaneous CSF rhinorrhea, paradoxical rhinorrhea, reservoir sign, Queckenstedt-Stookey test, ring sign, double-ring sign, halo sign, CSF rhinorrhea

Contributor Information and Disclosures

Author

Kevin C Welch, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, Loyola University Medical Center
Kevin C Welch, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery and American Rhinologic Society
Disclosure: Nothing to disclose.

Coauthor(s)

James Stankiewicz, MD, Professor, Chair, Program Director, Department of Otolaryngology-Head and Neck Surgery, Loyola University Chicago School of Medicine
James Stankiewicz, MD is a member of the following medical societies: American College of Surgeons
Disclosure: Nothing to disclose.

Medical Editor

Lanny Garth Close, MD, Chair, Professor, Department of Otolaryngology-Head and Neck Surgery, Columbia University College of Physicians and Surgeons
Lanny Garth Close, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, American College of Physicians, American Laryngological Association, American Society for Head and Neck Surgery, and New York Academy of Medicine
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Stephen G Batuello, MD, Consulting Staff, Colorado ENT Specialists
Stephen G Batuello, MD is a member of the following medical societies: American Academy of Otolaryngology-Head and Neck Surgery, American College of Physician Executives, American Medical Association, and Colorado Medical Society
Disclosure: Nothing to disclose.

CME Editor

Christopher L Slack, MD, Otolaryngology-Facial Plastic Surgery, Private Practice, Associated Coastal ENT; Medical Director, Treasure Coast Sleep Disorders
Christopher L Slack, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Medical Association
Disclosure: Nothing to disclose.

Chief Editor

Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado School of Medicine
Arlen D Meyers, MD, MBA is a member of the following medical societies: American Academy of Facial Plastic and Reconstructive Surgery, American Academy of Otolaryngology-Head and Neck Surgery, and American Head and Neck Society
Disclosure: Covidien Corp Consulting fee Consulting; US Tobacco Corporation unstricted gift unknown; Axis Three Corporation Ownership interest Consulting; Omni Biosciences Ownership interest Consulting; Sentegra Ownership interest Board membership; Syndicom Ownership interest Consulting; Oxlo  Consulting; Medvoy Ownership interest Management position

The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors Joseph Scianna, MD, and Srinivas Mukkamala, MD, to the development and writing of this article.

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