bubble_chart Overview

The cribriform plate of the ethmoid bone and the posterior wall of the frontal sinus are very thin and closely connected to the dura mater. If both the bone plate and the dura mater rupture during trauma, cerebrospinal rhinorrhea occurs. A fracture at the base of the middle cranial fossa may injure the superior wall of the larger sphenoid sinus, leading to cerebrospinal rhinorrhea. A cerebrospinal fluid fistula caused by a fracture of the tegmen tympani or the bony part of the eustachian tube can flow into the nasal cavity through the eustachian tube, resulting in cerebrospinal rhinorrhea. The incidence of cerebrospinal rhinorrhea is highest when caused by a fracture of the cribriform plate of the ethmoid bone. Cerebrospinal rhinorrhea may occur immediately at the time of injury or after a latent period; the latter is called delayed onset, possibly because only the bone plate was fractured at the time of injury while the dura mater remained intact. Later, under the influence of intracranial pressure and pulsation from breathing, the dura mater gradually herniates into the fracture gap, and over time, the fibers of the dura mater tear, forming a small hole, leading to cerebrospinal rhinorrhea. Another reason is that during the injury, a blood clot temporarily seals the tear in the dura mater and bone plate, but later, as the clot dissolves, cerebrospinal rhinorrhea occurs. Alternatively, the blood clot may temporarily seal the tear in the dura mater and bone plate during the injury, and after the clot dissolves, cerebrospinal fluid flows into the nasal cavity.

bubble_chart Diagnosis

If bloody fluid flows from the nostrils during trauma, with the center of the trace appearing red and the periphery clear, or if the colorless fluid discharged from the nostrils does not form a scab after drying, cerebrospinal fluid rhinorrhea should be considered. If the fluid discharged from the nostrils is clear and colorless, and the flow increases when bending the head forward or compressing the jugular vein, it suggests the possibility of cerebrospinal fluid rhinorrhea. The final diagnosis relies on quantitative glucose analysis, where cerebrospinal fluid contains more than 30mg% glucose; qualitative analysis is unreliable because tears or trace amounts of blood may contain minimal glucose, leading to false-positive results.

Locating the cerebrospinal fluid fistula is crucial for the diagnosis and treatment of this condition. There are many methods, but the most accurate and harmless is nasal endoscopy. This involves inserting a nasal endoscope through the anterior nostril and carefully examining five areas: the anterior and posterior parts of the roof, the sphenoethmoidal recess, the middle nasal meatus, and the pharyngeal opening of the eustachian tube. When examining each area, bilateral internal jugular vein compression can be applied to increase intracranial pressure and observe where cerebrospinal fluid flows into the nasal cavity. For example, if the fluid comes from the nasal roof, the fistula is in the cribriform plate of the ethmoid bone; if from the middle nasal meatus, the fistula is in the frontal sinus; if from the sphenoethmoidal recess, the fistula is in the sphenoid sinus; and if from the eustachian tube, the fistula is in the tympanic cavity or mastoid. Nasal radiographic examination can serve as a reference. The intrathecal marker method is less effective in identifying the fistula site and carries some risks. However, in recent years, the use of isotope ECT for fistula localization has shown a higher detection rate.

bubble_chart Treatment Measures

Traumatic cerebrospinal fluid rhinorrhea can mostly be cured by conservative treatment. This method includes preventing infection, preventing increased intracranial pressure, creating conditions to promote the natural healing of the fistula, adopting a head-elevated lying position, limiting water intake and salt consumption, avoiding forceful coughing and nose blowing, and preventing constipation. For fistulas located in the anterior part of the cribriform plate of the ethmoid bone, under surface anesthesia, 20% silver nitrate can be applied under direct vision to the mucosal edges of the fistula to create a wound surface that promotes healing. When applying the cauterizing agent, care must be taken to avoid excessive depth to prevent causing meningitis.

During conservative treatment, close observation of the condition is essential. If ineffective, surgical treatment may be performed.

Surgical indications: ① Cerebrospinal fluid rhinorrhea accompanied by pneumocephalus (intracranial air accumulation), brain tissue prolapse, or intracranial foreign bodies. ② Recurrent purulent meningitis. ③ Traumatic cerebrospinal fluid rhinorrhea that shows no improvement after 2–4 weeks of conservative treatment.

Surgical methods: Divided into intracranial and extracranial approaches. The intracranial method involves a craniotomy performed by neurosurgery to repair the fistula. The extracranial method can be further divided into intranasal and extranasal surgical approaches for fistula repair. In recent years, the use of sinus endoscopy has not only made it easier to locate the fistula but also allows for precise repair.