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

CSF Rhinorrhea

Author: Kevin C Welch, MD, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, Loyola University Medical Center
Coauthor(s): James Stankiewicz, MD, Professor, Chair, Program Director, Department of Otolaryngology-Head and Neck Surgery, Loyola University Chicago School of Medicine
Contributor Information and Disclosures

Updated: Oct 15, 2008

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.

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.

• Search for CME/CE on This Topic »

• Nasal Fracture (Sports Medicine)
• Functional Endoscopic Sinus Surgery (Otolaryngology and Facial Plastic Surgery)
• Cerebrospinal Fluid, Leak (Radiology)
• Skull Base, CSF Otorrhea (Otolaryngology and Facial Plastic Surgery)