CSF Otorrhea 

Updated: Jun 16, 2020
Author: Matthew B Hanson, MD; Chief Editor: Arlen D Meyers, MD, MBA 

Overview

Practice Essentials

Leakage of cerebrospinal fluid (CSF) though the ear structures is a rare but potentially life-threatening situation that requires rapid intervention. The presence of an abnormal communication of the sterile subarachnoid space with the flora of the sinonasal tract places the patient at great risk for meningitis. Indeed, an episode of meningitis may be the presenting problem for a person with an otologic CSF leak.

Even though a leakage of CSF is occurring through otologic structures, actual leakage of the fluid from the ear is not always present. CSF otorrhea occurs only if a perforation in the eardrum or a defect in the external ear canal is present. This is often the case when the leakage results from trauma or previous ear surgery. However, in the absence of such a defect, the fluid flows down the eustachian tube and manifests as a clear rhinorrhea. In this situation, it must be differentiated from a spinal fluid leak from other areas of the skull base, such as the sinuses. The reverse is also important to remember; just because the leak is through the nose does not mean that an otologic source is not a possibility.

The subject of CSF otorrhea covers a broad range of potential pathologies. Most of such leaks are postoperative and are a recognized complication of acoustic neuroma surgery.[1] Some occur as a result of middle ear surgery or erosive disease, such as cholesteatoma, sometimes many years later. Some may be the result of congenital abnormalities in the formation of the inner ear and the mastoid. In this article, the authors attempt to discuss all these related pathologies.

See the image below.

Coronal CT image of the temporal bone demonstrates 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.

A retrospective study by Oh et al indicated that an association exists between CSF otorrhea and superior semicircular canal dehiscence (SSCD), finding that 21% of patients with CSF otorrhea had concurrent SSCD, compared with just 2% of controls.[2]

Workup in CSF otorrhea

Unless the source is obvious, such as in a case of recent surgery or trauma, attempt to document that the draining fluid is in fact CSF.

Testing the fluid for glucose level helps to distinguish spinal fluid from nasal secretions, which are low in glucose. Contamination of the specimen with blood, serum, tears, or saliva may lead to a false-positive result.

Testing for beta2 transferrin, a substance found only in CSF, may identify the true nature of the substance with a greater degree of certainty.

Localization of an otogenic spinal fluid leakage is usually accomplished using imaging studies. Obtain a high-resolution computed tomography (CT) scan with axial and coronal sections. Unless an otologic source is certain, the scan should cover all three cranial fossae. Moreover, magnetic resonance imaging (MRI) may be helpful in pinpointing the site of a leak.[3]

Management of CSF otorrhea

Although not a primary treatment for CSF leaks, medication can often be used to decrease the production of spinal fluid. Such agents include diuretics (eg, furosemide, hydrochlorothiazide), carbonic anhydrase inhibitors (eg, acetazolamide), and steroids.

Otogenic CSF leak secondary to recent surgery or trauma can often be treated conservatively with a compressive dressing and bed rest with head elevation. Spinal fluid leaks following acoustic neuroma surgery respond to this treatment 80% of the time. This is also true of leaks associated with temporal bone fractures, which almost always seal in 3-4 weeks with this conservative therapy.[4]

Primary treatment of a spontaneous otogenic spinal fluid leak is surgical repair. In patients with postsurgical and traumatic leaks, surgery is reserved for those in whom conservative therapy is unsuccessful. The surgical approach is dictated by the nature and location of the defect.

Spontaneous leaks in children with otic capsule defects, such as Mondini deformity, can often be repaired by a transcanal approach. Because rarely any hearing is present, a stapedectomy is usually performed and the oval window obliterated with soft tissue. A transcanal approach can also be used in some cases of CSF leakage due to a patent Hyrtl fissure.

However, in most cases of spontaneous leakage, a transmastoid approach is preferred.[5]

Epidemiology

Frequency

Because this problem is so rare, the exact frequency with which it occurs is unknown. Leaks as a postoperative complication of skull base surgery represent the bulk of cases. This complication has been reported to occur in 6-12% of such cases. Leakage as a result of temporal bone fracture is the second most common etiology and occurs in 21% of patients with temporal bone fractures. Spontaneous leakage is rare, with less than 500 cases having been reported in the literature worldwide. Such leakage is more common in children (72%) than adults. Although rare, spontaneous leakage represents the greatest challenge to the clinician because the source of the leakage is not readily obvious.[6]

Using the MarketScan Commercial Claims and Encounters Database (Truven Health Analytics), Varshneya et al found that a CSF leak occurred in 202 of 13,861 pediatric patients with skull fracture (1.46%). That included 118 patients (58.4%) who presented with otorrhea, and 84 patients (41.6%) who presented with rhinorrhea.[7]

Meningitis is often the presenting symptom of CSF otorrhea. It is found in 93% of children and 36% of adults with spontaneous CSF leakage. Sensorineural hearing loss is another significant morbidity associated with spontaneous leaks in children and is present 82% of the time. Seizures are also a potential morbidity.[8, 9]

Etiology

The underlying etiology of a spinal fluid leak through the temporal bone is a violation of the bony and meningeal barriers that separate the subarachnoid space from the middle ear and mastoid. This means that a defect must exist not only in the bone, but also in the dura mater. Such problems may be postsurgical, posttraumatic, congenital, or related to otologic disease.

Pathophysiology

CSF leakage can result from a number of underlying pathologies. Such leaks can broadly be categorized into acquired and congenital.

Congenital cerebrospinal fluid leak

Congenital causes can be due to defects in the otic capsule itself, abnormal patency of pathways associated with the otic capsule, and defects distant from the otic capsule. Although congenital sources are more common in children, they can occur in people of any age and can even be observed in the geriatric population.[10]

A study by Stevens et al suggested that similar congenital pathoetiologic mechanisms are responsible for spontaneous CSF otorrhea and superior canal dehiscence (SCD). Using computed tomography (CT) scans, the investigators found that compared with patients with acoustic neuroma or otosclerosis, the height of the lateral skull base was significantly lower in individuals with CSF otorrhea or SCD. Moreover, in comparison with the other two groups, rates of pneumatization overlying the perigeniculate region and the internal auditory canal were significantly lower in the CSF otorrhea and SCD patients.[11]

Acquired cerebrospinal fluid leak

Acquired leaks result from temporal bone trauma, surgery, or infectious or neoplastic causes.[12] Acquired spinal fluid leakage is far more common than congenital leakage. Postoperative leakage following surgery is probably the most common cause of acquired CSF leaks. It is a recognized complication of acoustic neuroma removal and other skull base surgery. These leaks are usually evident in the early postoperative period. They rarely occur more than 2 months postoperatively.

Mastoid surgery for chronic ear disease is also a potential cause of an acquired CSF leak. When the dura is violated intraoperatively, the defect should be repaired immediately if possible. Frequently, however, the dura is not injured, but a defect is left in the bony plate of the tegmen. Over the years, the continuous pulsations of the CSF cause the dura to thin, allowing the arachnoid or brain to prolapse through this defect. This dura may become thin and spontaneously rupture, resulting in a leak of CSF many years after the initial surgery. In addition to dura, portions of brain tissue may also prolapse through the defect, resulting in an encephalocele.

Even in the absence of surgical intervention, similar problems may result from middle ear disease, most notably cholesteatoma. Cholesteatoma may erode the tegmen plate and allow herniation of dura or brain to occur over time.[13]

Spontaneous cerebrospinal fluid leak

Spontaneous leakage is leakage that occurs without an obvious antecedent pathology. Such leakage is usually due to some congenital defect in the temporal bone. Understandably, such defects are usually evident in childhood.

Spontaneous CSF leakage may result from a number of congenital deformities of the ear. Mondini deformity, an abnormal development of the cochlea, is frequently associated with CSF leakage. Such patients often have a patency at the lateral aspect of their internal auditory canal, allowing direct movement of CSF into the inner ear. A second defect, usually of the annular ring of the stapes footplate, then results in drainage of CSF into the middle ear. This usually causes loss of the remainder of hearing. A similar presentation may be observed in a patient with a widely patent cochlear or vestibular aqueduct.

Other deformities of the inner ear are also associated with spontaneous CSF leak. CSF can leak through a patent Hyrtl fissure, a congenital fusion plane found between the otic capsule and the jugular bulb (also termed the tympanomeningeal fissure). Such leakage may not be associated with any inner ear abnormalities, and the patient may have no evidence of a sensorineural hearing loss. Similar presentations may be observed in an abnormal patency of the petromastoid canal, which normally carries the subarcuate artery. Such patients may present with recurrent bouts of meningitis associated with what appears to be a unilateral serous otitis. Frequently, the true nature of the problem is not realized until a myringotomy is performed, at which time an unceasing flow of clear fluid is returned.

Although spontaneous CSF leakage is more common in children, reports of it occurring in people of greater age are increasing. In adults, spontaneous CSF otorrhea is often associated with a defect in the bone separating the middle ear space and the cranial vault. Such bony dehiscences are most commonly found on the floor of the middle fossa, along the tegmen plate. Tegmen dehiscences are found in up to 30% of autopsy specimens.

Continuous pressure of the CSF over the years results in formation of a meningocele or encephalocele. Defects in the middle fossa are associated with 88% of spontaneous leaks in adults. The remainder of spontaneous leaks are due to posterior fossa defects and arachnoid granulations, normal structures that absorb CSF. These structures are usually associated with the venous sinuses of the dura mater, but they have been found within the temporal bone on some autopsy specimens. Spontaneous leaks have recently been shown to be often associated with increased intracranial pressure. This is often manifested by a partially empty sella on the MRI scan.

Presentation

The chief presenting symptom one would expect when a CSF leakage through the ear is present is a clear watery drainage from the ear. This, however, is not always present and does not occur unless the eardrum or canal is in some way violated. If this is not the case, the leakage may be evident as a clear watery nasal discharge. This discharge may be positional or intermittent in nature and may only become apparent during straining or leaning forward. Some patients may notice no discharge at all but rather may report a strange salty taste in the back of the throat.

Often, a patient with an otogenic spinal fluid leakage presents with a unilateral hearing loss. The nature of the hearing loss is important. A sensorineural hearing loss suggests an associated abnormality of the inner ear, such as a Mondini deformity. However, the loss may be conductive, suggesting a leak elsewhere in the temporal bone. Such a presentation may be very similar to that of a unilateral serous otitis media and may be mistaken for such. The realization of the true identity of the fluid may only be made at the time of myringotomy, when clear fluid pours unceasingly from the incision. When such an event occurs, the ear canal is often packed to prevent continuous drainage from the ear and allow the eardrum to heal. Other authors think that packing may cause stasis and provide a nidus for infection, hastening meningitis, and they recommend only a loosely placed, frequently changed sterile cotton ball placed in the conchal bowl. A full workup should be immediately undertaken.

A common presentation for a spontaneous spinal fluid leakage is an unexplained episode of meningitis. In such situations, the source of the leakage may not be readily apparent. A history of unilateral hearing loss or chronic ear disease may suggest which side is involved. Absence of otologic symptoms and a history of sinonasal disease may suggest an anterior source of leak. In situations of leakage following surgery and trauma, the source of the leak usually is readily apparent.

Patients suspected of having a spinal fluid leakage should undergo complete otologic, neurologic, and head and neck examination. Use binocular microscopy to examine the ears. Pneumatic otoscopy may be helpful in demonstrating fluid within the middle ear space, especially when that fluid is very clear. Tuning fork evaluations can be used to demonstrate a conductive hearing loss. If possible, perform complete audiometric evaluation.

An important part of the physical examination is an attempt to demonstrate the leak. Usually, the patient is asked to perform for the examiner the maneuver with which they notice the leak, such as straining or leaning forward. With the Dandy maneuver, the patient leans forward with the head pointed down while performing a Valsalva. This maneuver often results in the appearance of clear fluid from the nostril of a person with a CSF leak. The side of the nostril from which the leakage occurs usually agrees with the side of the otologic source.

Indications

Leakage of CSF though the ear structures places the patient at great risk of meningitis. Surgery is therefore indicated to repair this problem in most situations. Leaks occurring following trauma or recent skull base surgery can often be treated conservatively using a pressure dressing and a lumbar drain. Surgery is recommended for patients in whom this conservative therapy is unsuccessful.

Relevant Anatomy

See Etiology and Pathophysiology.

Contraindications

In patients with postsurgical and traumatic leaks, surgery may not be indicated because it is reserved for those in whom conservative therapy is unsuccessful.

 

Workup

Laboratory Studies

See the list below:

  • Unless the source is obvious, such as in a case of recent surgery or trauma, attempt to document that the draining fluid is in fact CSF.

    • Testing the fluid for glucose level helps to distinguish spinal fluid from nasal secretions, which are low in glucose. Contamination of the specimen with blood, serum, tears, or saliva may lead to a false-positive result.

    • Testing for beta2 transferrin, a substance found only in CSF, may identify the true nature of the substance with a greater degree of certainty. Beta2 transferrin is also found to a lesser degree in perilymph, but perilymph would not be expected to cause a large volume of leakage. However, the test for beta2 transferrin may not be readily available and the result may not be returned for days to weeks.

Imaging Studies

See the list below:

  • Localization of an otogenic spinal fluid leakage is usually accomplished using imaging studies.

  • Obtain a high-resolution CT scan with axial and coronal sections. Unless an otologic source is certain, the scan should cover all 3 cranial fossae.

    • Check the otic capsule for abnormal morphology, such as a Mondini deformity. Note the sizes of the vestibular and cochlear aqueducts. Check the tegmen plates of the posterior and middle fossae for defects.

    • Localization of leakage sites with CT scanning may be enhanced with the use of intrathecal contrast, such as iopamidol or iohexol.

    • The presence and location of pneumocephalus on CT scanning may help to identify and localize a CSF leak.

  • MRI may be helpful in pinpointing the site of a leak.[3]

    • Spinal fluid, bright on T2 sequences, may be observed entering the middle ear.

    • In cases where a tegmen defect is observed on CT scanning, MRI may demonstrate whether or not brain tissue is prolapsed into the middle ear. Because this is important information for surgical planning, an MRI is a critical adjunct when a defect is found in the bony plate of the tegmen or the posterior fossa.

    • A partially empty sella has recently been recognized as a possible sign of increased intracranial pressure. The increased CSF pressure causes infiltration of the sella with CSF and displacement of the pituitary tissue. This finding, previously thought to be unrelated and incidental, has been shown to occur in 71% of patients with spontaneous CSF leaks.

 

Treatment

Medical Therapy

Although the presence of a CSF leak places the patient at risk for meningitis, the use of prophylactic antibiotics is controversial. Many believe the use of antibiotics in the absence of infection has the effect of selecting out resistant organisms among the normal flora, complicating the treatment of meningitis when it does arise. They believe antibiotics should be withheld unless signs and symptoms of meningitis occur and diagnosis is confirmed by spinal tap. Then, broad-spectrum antibiotics are instituted until cultures and sensitivities are returned.

Others believe that the routine use of prophylactic broad-spectrum antibiotics is advised in CSF otorrhea. The initial signs of meningitis may be subtle, and irreparable harm may occur to the CNS by the time obvious meningitic signs are present. A number of published studies have shown that the risk of meningitis is significantly reduced when prophylactic antibiotics are used in posttraumatic CSF leakage, and their use in this situation is generally recommended. However, the results of these studies can probably not be extrapolated to postoperative and spontaneous leaks.

Prophylactic antibiotics should always be used in patients who are immunosuppressed and when soilage of the central nervous system is obvious. In these situations, overwhelming infection may be present before signs of meningitis are noted. Antibiotics are also routinely used when an indwelling device, such as a lumbar or ventricular drain, is used.

Often, medication can be used to decrease production of spinal fluid. Such medications include diuretics (eg, furosemide, hydrochlorothiazide), carbonic anhydrase inhibitors (eg, acetazolamide), and steroids. These medications are not used as a primary therapy for a CSF leak, but they are valuable adjuncts to treatment. During the diagnosis and evaluation phase, they may hamper the ability to locate the leak if the output is low.

Otogenic CSF leak secondary to recent surgery or trauma can often be treated conservatively with a compressive dressing and bed rest with head elevation. Spinal fluid leaks following acoustic neuroma surgery respond to this treatment 80% of the time. This is also true of leaks associated with temporal bone fractures, which almost always seal in 3-4 weeks with this conservative therapy.[4]

Postoperative leakage though an incision line can often be stopped with a single well-placed mattress stitch.

Continuous lumbar spinal fluid drainage may serve as a useful adjunct to the conservative treatment of a spinal fluid leak related to surgery or trauma. Continuous drainage of spinal fluid serves to decrease the pressure head against the leak to allow natural healing to occur. Do not use spinal drains when the site of leakage is not known because they may hamper localization and allow air to flow into the cranial vault, resulting in pneumocephalus. In cases of spontaneous leakage, the lumbar drain may help facilitate healing after surgical repair.

Surgical Therapy

Primary treatment of a spontaneous otogenic spinal fluid leak is surgical repair. In patients with postsurgical and traumatic leaks, surgery is reserved for those in whom conservative therapy is unsuccessful. Surgical approach is dictated by the nature and location of the defect.

Spontaneous leaks in children with otic capsule defects, such as Mondini deformity, can often be repaired by a transcanal approach. Because rarely any hearing is present, a stapedectomy is usually performed and the oval window obliterated with soft tissue. A transcanal approach can also be used in some cases of CSF leakage due to a patent Hyrtl fissure.

However, in most cases of spontaneous leakage, a transmastoid approach is preferred.[5] This is especially true if the exact site of the leakage is not known or suggested on imaging studies. The exposure of a mastoidectomy usually allows excellent visualization of the leakage site. The site can often be repaired with a small amount of fascia supported by Gelfoam. If the leak is related to a small ( < 1 cm) defect in the bone of the tegmen, the fascial repair can be supported with a tragal cartilage graft placed between the intact bony edges and the dura.

Occasionally, a fat or muscle graft may be needed. In rare cases, the exact site of leakage is not found, and diffuse leak is observed from multiple mastoid air-cell tracts. In this situation, the mastoid may need to be obliterated with fat. Obliteration of the middle ear and eustachian tube may also be required, especially if the leakage is not limited to the mastoid.

A study by Kim et al supported the efficacy of transmastoid procedures for patients with spontaneous temporal bone CSF leaks. In the study, 15 patients (16 ears) with temporal bone ̶ related chronic otorrhea and conductive/mixed hearing loss underwent transmastoid surgery. The procedures were multilayered, with autologous mastoid bone, temporalis fascia, and tissue sealant typically employed. The operations were successful in all but one ear, which was subsequently treated with a middle fossa craniotomy. None of the patients suffered serious complications, and the air-bone gap, which had a mean preoperative value of 19 dB, was 12 dB or less following surgery in the 14 patients for whom postoperative audiograms were available.[14]

Leaks may occur in ears that have previously undergone canal wall down mastoidectomy. Removal of the canal wall may also be dictated by the extent of disease when the leak is associated with an active cholesteatoma. In these situations, the external ear and mastoid epithelium must be completely removed and the ear canal sewn over. Abdominal fat is then used for obliteration.

Leaks occurring from defects of the posterior cranial fossa anterior to the sigmoid sinus present a special problem. This is the area of the basal cistern, where no arachnoid mesh is present. Leakage from this area is explosive and profuse and is not well controlled with fascia alone. A large fat graft obliterating the mastoid is usually required.

If a leak is due to a large (>1 cm) defect in the floor of the middle fossa, the problem is best addressed with a combined middle fossa/transmastoid approach. A mastoidectomy is performed first to identify the site of leakage. Do not attempt to reduce herniated brain tissue. Such encephaloceles do not contain functioning brain tissue and should be excised using bipolar cautery. Once the defect is identified, use the middle fossa approach for repair. The middle fossa affords excellent visualization of the defect and an opportunity to use the intact bony edges of the defect to hold any repair material in place.

Recommended repair of such large defects is with a 3-layer technique. A layer of calvarial bone is sandwiched between 2 layers of fascia. Use of a bone graft helps to resist the pulsation of the CSF and prevent formation of a new meningocele. The calvarial bone can be harvested by splitting the bone flap taken for the craniotomy.[15] Fibrin glue is a very useful adjunct to such a repair and helps seal the components in place.

Fascia for grafting is usually harvested from the temporalis muscle. This muscle can also serve as the source of a muscle graft. If a vascularized pedicled flap is desired, this can be harvested from the superficial temporal fascia.

If adequate grafting material is not readily available in the operative wound, it may need to be harvested from elsewhere in the body. One such site is the fascia lata found on the lateral thigh. This site is capable of providing large amounts of fascia for dural repair.

Several local vascularized flaps are available to be used for reconstruction in the repair of a CSF leak. These flaps include temporalis muscle, galeal flaps, and superficial temporoparietal fascia. These flaps are especially useful following skull base surgery, where large dural defects are often created. In rare cases of very large defects, a vascularized free flap may be required.

Several forms of commercially available materials are now available to assist in the repair of a CSF leak. One such material is made from bovine pericardium. This material is very tough, but it is pliable and easy to work with. Hydroxyapatite cement may also be used to aid in reconstruction of bone defects. Fibrin glue alone cannot be used as a repair material, but it can be used to secure the repair components. Each of these substances is biocompatible and becomes integrated with host tissue. Other synthetic materials, such as silicone sheeting, Marlex mesh, titanium plates, and methylmethacrylate, do not become integrated with host tissue and have a high rate of infection or extrusion. The author prefers that even biocompatible materials not be used if the supply of the patient's own tissue is adequate.

Continuous lumbar spinal fluid drainage is an important adjunct to surgical repair of otogenic CSF leakage. The drain is usually placed at the beginning of treatment, but it should be left clamped until the leakage site is identified. After the surgery, remove a small amount of spinal fluid on an hourly basis to decrease the pressure head against the repair. Care must be taken not to remove too much spinal fluid because this may draw air into the cranium through the repair, resulting in pneumocephalus. The patient must remain on bed rest as long as the drain is in place.

Postoperative Details

In most cases, the postoperative patient should be observed in an ICU setting. The intensive care setting ensures that neurologic changes heralding an arising complication will be rapidly noticed and addressed. Perform hourly neurologic checks for the first 24 hours after surgery and then every 2 hours until the patient is well enough to leave the unit.

An important aspect of ICU care is monitoring of the lumbar drain. Drainage should be accomplished by draining a specific amount every hour, usually about 10 mL. Occasionally, this causes severe headache, in which case a smaller amount can be removed or the fluid can be removed less frequently (eg, 5 mL every half hour). Some have advocated leaving the drain open at a level just below the level of the leak, allowing the spinal fluid to drain at its own pace while maintaining a low pressure against the repair. This technique has led to some reports of pneumocephalus and is generally not recommended. Others have suggested attaching the drain to an IV pump so that a steady even flow can be maintained. This, too, may be risky because it may cause too much drainage and result in pneumocephalus.

While the drain is in place, patients should remain on bed rest. Use position changes and compression boots to prevent bedsores and deep venous thrombosis.

Check spinal fluid drainage every 2 days with a Gram stain and a culture.

The lumbar drain is usually left in place for 2-3 days postoperatively. If no sign of leakage is present, it is clamped and the patient is observed for an additional 24 hours. If no further leakage is observed, the drain is then removed.

In many cases of surgical repair of a CSF leak, ICU monitoring may not even be necessary. These include cases treated by a transcanal approach that do not require lumbar drainage.

Complications

The risks faced by patients undergoing surgery to repair a CSF leak are far less than those they face if the leak remains unaddressed. Although some leaks may continue in some patients for prolonged periods, any leak is likely to eventually result in meningitis if monitored for long enough. The surgical risks associated with the surgery are no greater than those for any other similar neurologic surgery.

Neurologic surgery carries risks for intracranial bleeding, cerebral edema, hydrocephalus, stroke, and of course, meningitis. Any change in mental status in the postoperative period must be rapidly evaluated and addressed. An immediate CT scan of the brain performed without contrast usually demonstrates any bleeding, edema, stroke, or hydrocephalus. If the findings of this study are normal, it should be followed by a lumbar puncture. Lumbar puncture should not be performed before these entities are ruled out because removal of spinal fluid may result in brain herniation. However, in most situations, a lumbar drain is already in place. When mental status changes occur, the drain should be clamped until the CT scan findings are shown to be normal. A sample of the fluid in the reservoir can be sent off at any time.

A study by Stevens et al indicated that in patients with spontaneous CSF otorrhea who undergo surgical treatment, those with a thin tegmen (< 0.9 mm thick) tend to have a higher incidence and rate of adverse perioperative outcomes. The study involved 30 patients with thin tegmens and 15 patients with thicker tegmens, with leak recurrence more common in the thinner-tegmen group.[16]