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Cerebrospinal fluid rhinorrhea may be classified as traumatic (>90%) or nontraumatic (<10%). Approximately 80% of all traumatic leaks occur in the setting of accidental trauma, and the remaining traumatic leaks occur after neurosurgical and rhinologic procedures. Nontraumatic etiologies include neoplasms and hydrocephalus.

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Idiopathic nontraumatic cerebrospinal fluid rhinorrhea has been linked with elevated intracranial pressure. Numerous studies have confirmed an association of this entity with both benign intracranial hypertension and empty sella syndrome.

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Clinical presentation includes unilateral watery drainage with a characteristic metallic or salty taste, often in the clinical setting of possible etiologic factors.

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The differential diagnosis for watery rhinorrhea includes allergic rhinitis, vasomotor rhinitis, and retained nasal saline irrigation fluid as well as cerebrospinal fluid otorrhea that is draining through the eustachian tube.

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Confirmation of a cerebrospinal fluid leak can be achieved through detection of β₂-transferrin or β-trace protein in nasal secretions.

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Cisternogram studies provide diagnosis confirmation and localization information. Both CT cisternography and radionuclide cisternography require lumbar puncture for the administration of tracer agent, whereas MRI cisternography can be achieved solely through specific imaging protocols. Radionuclide cisternography has poor sensitivity and poor spatial resolution. Both CT cisternography and MRI cisternography offer much greater spatial resolution but still require the presence of a relatively large, active leak for reliable detection.

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Endoscopic examination after the administration of intrathecal fluorescein can confirm the diagnosis of a cerebrospinal fluid leak and indicate its location. Dilute fluorescein must be used; serious neurologic sequelae have been reported after higher intrathecal doses of this agent.

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Endoscopic repair has emerged as the preferred modality for most cases of cerebrospinal fluid rhinorrhea requiring operative repair. During endoscopic repair, the leak site is identified and then closed with autogenous graft materials (fascia, free bone graft, fat), allograft (acellular dermal allograft), and xenogeneic collagen dural substitutes, or a combination. A free mucosal graft is typically placed over these materials, and the reconstruction is secured with surgical sealant and resorbable and nonresorbable packing material.

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The role of prophylactic antibiotics remains controversial. Some data suggest that antibiotics should be administered after detection of a cerebrospinal fluid leak, but the data are far from conclusive. Certainly, in the presence of active infection adjacent to the leak site, antibiotics are prudent.

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Traumatic cerebrospinal fluid leaks are likely to resolve with conservative measures (lumbar drainage and bed rest); operative repair is reserved for those cases in which these measures fail or in which massive injury requires urgent formal operative exploration and repair.

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Cerebrospinal fluid leak that is recognized at the time of surgery should be repaired during that procedure. Cerebrospinal fluid rhinorrhea that develops after surgery may be managed conservatively at first, but most cases require operative repair.

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Nontraumatic cerebrospinal fluid rhinorrhea is unlikely to resolve spontaneously. After potential etiologic factors (brain tumor) have been excluded, operative repair is warranted.