Cribriform Plate Fracture After Head Trauma: Symptoms, CT Findings, and Treatment Options
The cribriform plate (filter plate) is a very thin bony structure located on the upper surface of the ethmoid bone. It separates the nasal cavity from the anterior cranial fossa and carries the olfactory nerves (olfactory fibers). Fracture of this structure following trauma can lead to serious complications. Recognizing, distinguishing, and repairing this fracture using appropriate surgical techniques, especially after head trauma, is crucial. This article will detail the causes, differential symptoms, diagnostic methods, and surgical techniques of a patient with a traumatic left-sided cribriform plate fracture, along with a CT image (above). First, I'd like to share a CT image and video of the patient with you.
The cribriform plate contains deep grooves known as olfactory fossae, which support the olfactory bulbs. Olfactory nerve fibers enter the roof of the nasal cavity to provide the sense of smell, called olfactory foramina.
A cribriform plate fracture is a potentially serious injury that can be easily overlooked by physicians and patients. This fracture is often an indication of serious head or facial trauma. Cribriform plate fractures can cause health problems, including olfactory impairment, cerebrospinal fluid leakage, and meningitis or intracranial infection. Early diagnosis is crucial to avoid these complications.
Rapid diagnosis can facilitate early treatment and reduce the risk of these potentially life-threatening complications. Therefore, when evaluating a patient with facial trauma, physicians must consider the differential diagnosis of eccentric plate fractures and dural fistulas to facilitate early diagnosis and prevent serious complications.
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| The CT scan above shows a patient who had sustained trauma to the frontal area of the face for years and several more head injuries, subsequently developing nasal discharge (csf rhinorrhea). The dental implant, which had extended into the patient's left maxillary sinus and caused a cyst within the maxillary sinus, is also visible. |
In the CT scan video above, a patient with traumatic CSF rhinorrhea (cerebrospinal fluid rhinorrhea) presents with a mouse cursor over the CT scan to reveal the fracture in the left cribriform plate. The dental implant, which has extended into the patient's left maxillary sinus and caused a cyst within the maxillary sinus, is also visible.
The above magnetic resonance imaging shows a left cribriform plate fracture, a small amount of brain herniation, and cerebrospinal fluid leakage (shown by the mouse arrow).
Traumatic Cribriform Plate Fracture Causes and Pathophysiology
Cribriform plate fractures are often associated with high-energy head trauma; typical causes include traffic accidents, falls, combat injuries, and blows.
In some cases, penetrating injuries (e.g., transnasal foreign bodies) can damage this area.
Rarely, a cribriform plate defect can occur due to iatrogenic causes, endoscopic sinus surgery, or nasal procedure errors. There is a Keros classification regarding the risk of cribriform plate injury during endoscopic sinus surgery (you can check out the links
for more information). Our patient has not had any nose surgery before and can be classified as Keros type 2 based on the tomography image.
Anatomical and structural features
The cribriform plate, being the thinnest part of the skull base, is prone to fracture in facial trauma.
The dura mater may be damaged with a fracture, which can lead to cerebrospinal fluid (CSF) leaking from the subarachnoid space. CSF rhinorrhea (leaking of brain fluid through the nose) occurs.
Fractures of this bony plate can cause partial or complete anosmia due to severing the olfactory nerves or crushing the olfactory bulb. Patients may experience cerebrospinal fluid leakage, as well as decreased or complete loss of smell after the trauma. The dura overlying the cribriform plate is thin and tightly adhered to the skull; therefore, cribriform plate fractures can easily tear the dura, causing cerebrospinal fluid (CSF) to leak into the nasal cavity. The image I shared with you in this article shows images of dural damage above and below the cribriform plate fracture, as well as images of CSF fluid. The risk of infection, particularly bacterial meningitis, increases with persistent CSF leakage. Damage to the dura can lead to various intracranial complications, such as pneumocephalus, encephalocele, and ascending infections leading to meningitis.
Etiology
The most common cause of cribriform plate fractures is blunt trauma to the face, which accounts for 80-90% of cases (source link https://www.ncbi.nlm.nih.gov/books/NBK562192/). A cribriform plate fracture requires a severe frontal impact and a significant mechanism of injury. This fracture rarely occurs alone and is usually associated with other facial bone fractures. The patient I share with you in this article did not have an additional facial fracture. Overall, the most common cause of midface fractures in adults is traffic accidents, which account for almost two-thirds of cases. The next most common cause is assault (21%), followed by falls (9%) (source link https://pmc.ncbi.nlm.nih.gov/articles/PMC4016399/). Among other facial injuries, occupational and sports injuries account for a smaller percentage.
Midface fractures in young children are more commonly caused by falls. Sports injuries are prevalent in children aged 11-14, with assault becoming most common between the ages of 15-18. Gunshot wounds and other penetrating trauma are also among the causes of these fractures. Cribriform plate fractures can also occur as a complication of endoscopic sinus surgery. However, this condition is generally rare, and the rate of CSF leak due to iatrogenic complications has been reported to be less than 1% (source link >> https://pubmed.ncbi.nlm.nih.gov/23257548/).
Distinctive Signs and Clinical Findings: Typical Symptoms
Rhinorrhea (clear, watery nasal discharge): Watery nasal discharge, particularly aggravated by bending forward, is indicative of CSF leakage. Post-traumatic nasal discharge, which can be dripping or leaking, is typical.
Hyposmia / Loss of smell (anosmia): The ability to smell may be reduced or lost due to damage to the olfactory nerves. Its onset after trauma can also be distinctive. However, decreased smell may also occur in cases of traumatic septum fractures, septal hematomas, or nasal constriction due to clots or swelling.
Headache / Position-dependent headache: Headaches that worsen when standing and decrease when lying down may occur (similar to low CSF pressure syndrome).
Air-brain (intracranial aerocele / pneumoencephalus / pneumatocele): If the fracture site is connected to air, intracerebral air can be seen; gas pockets can be detected on CT scans. This condition can occur when the dura is damaged in cribriform plate fractures.
Meningitis symptoms: Fever, neck stiffness, and impaired consciousness. Pathogens can reach the brain if there is CSF communication with the outside environment. In the long term, meningitis and other intracranial complications can occur due to a CSF fistula.
Patient Evaluation for Cribriform Plate Fracture - History and Physical Examination
A patient presenting to the emergency department with severe facial trauma requires a comprehensive evaluation. A primary examination should be performed immediately to assess and treat life-threatening injuries. While facial trauma may sometimes be the cause in patients with this fracture, the patient may present with only headaches and nasal discharge. As in the emergency patient evaluation, the examination should begin with a thorough assessment of airway patency, breathing, and circulation. If the patient mentions trauma as the etiology, it should be considered that facial fractures can cause changes in facial anatomy, airway obstruction, and the risk of aspiration. If the patient is in good general condition, has a normal neurological examination, and no other fractures or injuries, and only has a cribriform plate fracture, various imaging techniques can be utilized for further detailed evaluation and to assess for CSF rhinorrhea.
Clear rhinorrhea, in particular, is highly suspicious for a cribriform plate fracture with a dural fistula. Patients should also undergo an ENT examination. Stable patients with cribriform plate fractures often present with post-traumatic midface pain and epistaxis. Epistaxis can sometimes mask CSF rhinorrhea. If a clear nasal discharge persists after the epistaxis resolves, this is a significant concern for a post-traumatic CSF leak.
Cribriform Plate Fracture Patient Evaluation and Diagnostic Studies
Computed Tomography (CT, high-resolution, bone window)
The initial imaging modality of choice for diagnosing cribriform plate fractures is maxillofacial computed tomography (CT). Ideally, a high-resolution CT scan with 1 mm sections, including sagittal, coronal, and axial views, is obtained (source link https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0037-1601370). Images the fracture line and bone defect. The location, size of the fracture, and the status of the adjacent affected structures can be determined. An example of a CT image of a left cribriform plate fracture in the patient above is presented.
CT Sphenoparicular Sinus + Multiplanar Reconstruction
Used to evaluate the anterior floor structures in different planes.
The axis and direction of the fracture are examined in detail.
CT Cisternography (with intrathecal contrast)
The anatomical location of the leak is determined by administering contrast material.
This is the preferred method, especially when the precise location of the defect is unclear.
MRI (MR-cisternography, T2-weighted images)
Used for soft tissue assessment, it visualizes nerve structures, brain tissue, and cerebrospinal fluid. When contrast is used, it may reveal concomitant sinus or meningeal changes.
Filter Test in CSF Rhinorrhea
The filter test can be used to help detect CSF in bloody secretions. This test is controversial. When placed on filter paper, CSF moves outward while blood moves inward, creating a "double halo" sign. While quick and easy to perform, this test has not been shown to be significantly sensitive or specific for detecting CSF; therefore, further diagnostic studies are necessary.
Beta-2-Transferrin and Beta-Trace Protein Testing in CSF Rhinorrhea
If available, nasal and/or otic secretion samples should be collected and evaluated for beta-trace protein and beta-2-transferrin. Beta-trace protein is found in high concentrations in CSF. Beta-2-transferrin is found in CSF, aqueous humor, and perilymph. Positive tests for these two substances are a strong indicator of a CSF leak. This is the gold standard test for determining whether the fluid in nasal discharge is from the CSF. Blood, mucus, and sinus secretions are not positive on this test, while CSF is.
Nuclear Medicine Methods (e.g., radiolabeled glucose, etc.)
Used less frequently; may be helpful in localization.
Cribriform Plate Fracture Differential Diagnosis
Since severe facial trauma is often the cause in these patients, these patients with cribriform plate fractures should be evaluated for concurrent traumatic brain injuries (TBI), intracranial hemorrhage, and other facial fractures.
Sometimes, when a patient presents with only a runny nose, when CSF rhinorrhea becomes chronic, they may be diagnosed with allergic rhinitis, simple upper respiratory tract infection, or sinusitis. A thorough history and thorough examination can prevent misdiagnosis and delayed treatment.
Cribriform Plate Fracture Treatment
Cribriform plate fracture treatment requires hospitalization, and in some patients, a conservative follow-up protocol may be implemented. Most traumatic CSF leaks heal spontaneously within the first seven days, and lumbar drainage can be applied to reduce intracranial pressure and facilitate spontaneous healing (source link https://pubmed.ncbi.nlm.nih.gov/1505379/). A small percentage of post-traumatic CSF leaks can persist for several months. Patients with CSF rhinorrhea that persists for more than seven days should be considered for surgical closure. This is because leaks that persist for more than seven days increase the risk of developing bacterial meningitis.
Endoscopic repair has been shown to be highly effective, with a healing rate exceeding 95%, and requires no additional treatment. If the fractures are in the extreme anterior cribriform, adequate endoscopic access may not be possible, and an open surgical approach may be necessary. In this case, a neurosurgeon and an ENT specialist may need to perform the surgery simultaneously. However, in rare cases, an anterior craniotomy may be necessary. Patients with active CSF leakage are given prophylactic antibiotic treatment in many centers.
Initial Approach and Treatment Planning for a Cribriform Plate Fracture Patient
When a patient with a traumatic cribriform plate fracture presents to the emergency department, initial conservative treatment includes bed rest and avoiding Valsalva maneuvers or other maneuvers that could increase intracranial pressure. Acetazolamide can be used to reduce CSF pressure, and a lumbar drain may be planned to measure CSF pressures, maintain a lower intracranial pressure, and facilitate spontaneous resolution of the leak.
Patient monitoring and monitoring of CSF leakage are important. If the leak persists for more than 1 week, surgical repair may be considered. High-resolution CT imaging with 1-mm incisions is the preferred imaging modality for planning surgical repair to allow clear and accurate assessment of the fracture site, and intraoperative navigation systems can also be used to obtain a 3D image. This imaging can also identify post-traumatic encephalocele that requires treatment. Most leaks associated with anterior cribriform fractures can be repaired endoscopically, and repairs can utilize fascial or bone grafts, vascularized mucosal flaps, or allogeneic materials. It is important to confidently identify the leak site intraoperatively; this may require ethmoidectomy, partial middle turbinate resection, or sphenoidotomy during endoscopic repair. If the leak remains undetected, intraoperative intrathecal fluorescein injection can help localize the leak (source link https://www.thieme-connect.de/products/ejournals/abstract/10.4103/ajns.AJNS_363_20).
Surgical Indications for Traumatic Cribriform Plate Fracture
Surgical treatment should be considered if the following conditions are present:
- The leak persists for more than 7 days
- There is a history of recurrent meningitis
- There is a large defect with a clear airway connection
- When conservative treatment fails
If the patient has other intracranial injuries, simultaneous repair is considered.
Traumatic Cribriform Plate Fracture Treatment - Surgical Techniques
Surgical repairs aim to close the damaged fistula area, reestablish the CNS-CSF barrier, control infection, and protect adjacent structures (olfactory nerves).
Endoscopic Endonasal Approach (Minimally Invasive)
This is the most commonly used technique with a high success rate (approximately 95% or more). An endoscope is inserted through the nasal cavity to visualize the damaged area and close the defect. During this procedure, mucosal flaps, dura mater, and support materials (fatty tissue, fibrin glue, fascia lata, nasal septum mucosa flap) can be used to close the fistula area.
Endoscopic techniques are advantageous because they are minimally invasive and promote rapid postoperative recovery. Navigation (image-guided surgery) can be used during endoscopic repair, making surgery safer, especially in complex cases.
Whether or not an endoscopic approach is preferred in surgical planning is determined by the size/location of the defect, the general condition of the patient, and the presence of other intracranial injuries.
Open Surgical Approaches (Rarely Necessary)
Techniques such as frontal craniotomy, subfrontal approach, and bifrontal bone opening are used. Pericranial flaps, fascia lata grafts, fat tissue, and polymer membranes may be used for defect closure. Additionally, cranial plate reconstruction (cranioplasty) or subdural drainage may be required.
Combined (Hybrid) Techniques
In some cases, open and endoscopic approaches are used together, particularly in advanced skull base injuries.
Additional Techniques
Lumbar drainage: Short-term drainage to reduce CSF pressure before or after surgery. Increases the success of endoscopic repair.
Artificial bone grafts/matrices: Can be used to provide support and close the bone defect.
Traumatic Cribriform Plate Fracture Prognosis
The prognosis of a cribriform plate fracture can vary and depends largely on the initial presentation, associated injuries, and the location and size of the defect. In patients with good general condition and minimal CSF rhinorrhea who do not require surgical intervention, the prognosis is good, and CSF leaks usually resolve spontaneously. When a cribriform plate fracture is present alone, the prognosis is generally good, and complications, morbidity, and mortality are largely due to other associated injuries resulting from the trauma rather than the cribriform plate fracture itself.
Complications of Traumatic Cribriform Plate Fractures
Loss of Smell
Various health problems can arise in patients due to this fracture. Loss of smell, or anosmia, is a common complication of a cribriform plate fracture. The injury results from damage to the olfactory nerves or the olfactory bulb. Anosmia can be partial or complete. It can also occur after surgical repair. If neurosurgical repair is necessary, a frontal lobe-free approach has been shown to reduce the risk of olfactory avulsion and associated anosmia (source link https://onlinelibrary.wiley.com/doi/10.1097/01.mlg.0000217533.60311.e7).
Meningitis and Other Intracranial Complications
Patients with a history of cribriform plate fractures are at increased risk of ascending infections and bacterial meningitis. Patients with a diagnosed CSF leak are more likely to develop meningitis. Higher rates of meningitis have been noted in cases where fractures occurred more than a year prior. Surgical repair is recommended for acute CSF fistulas that persist for more than a week and do not improve, to prevent meningitis.
Intracranial aerocele / pneumoencephalus / pneumatocele
The cribriform plate is a thin section of the ethmoid bone that forms a "barrier" between the nasal cavity and the anterior cranial fossa. When this area fractures, a direct opening (fistula) forms between the inside of the skull and the nasal cavity. This creates a "pathway" for air (or air + CSF movement under pressure).
The mechanism of pneumoencephalus in cribriform plate fractures: "Airflow by Pressure Difference"
The cribriform plate fractures as a result of trauma, and the dura mater and mucosal barrier are also torn. This creates an opening between the nasal cavity (at atmospheric pressure) and the intracranial space (negative-pressure CSF space). When the patient breathes through the nose, sneezes, coughs, or blows their nose, the air pressure in the nose increases. This pressure difference allows air to pass through the fracture line and into the skull—this is called pneumocephalus.
Headache
A cribriform plate fracture with a persistent CSF leak can cause a headache syndrome. Headaches worsen in the upright position and improve in the supine position. As the amount of CSF leaked increases, the headache worsens. This syndrome resembles a post-dural CSF puncture headache, and the etiology (decreased intracranial pressure) is the same.
Problems related to concomitant nasal and septal injuries
Clinicians should evaluate patients with cribriform plate fractures and midface trauma for nasal septal hematoma. An undiagnosed nasal septal hematoma can cause avascular necrosis of the septal cartilage and subsequent saddle nose deformity.
Problems with nasotracheal tube and nasogastric tube placement in patients with cribriform plate fractures
Nasotracheal intubation and nasogastric tube placement are contraindicated in patients with midface trauma due to the possibility of tubes being passed into the cranial vault through the fractured cribriform plate.
Murat Enoz, MD, Otorhinolaryngology, Head and Neck Surgeon
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