What is Cribriform Plate Fractures?
The cribriform plate is a part of a bone in our skull called the ethmoid bone. The bottom part of our skull is made up of different bone sections, including the frontal, ethmoid, sphenoid, temporal, and occipital bones. This base of the skull is split into three areas: the anterior fossa, the middle fossa, and the posterior fossa. The ethmoid bone sits in the centre of the anterior fossa and extends from the middle of the eye sockets over the nasal separator and forms the top section of our nose.
This thin bone structure has deep tracks, or olfactory fossa, which hold the olfactory bulbs, a part of our brain that helps us smell. The bone has little holes, known as olfactory foramina, where olfactory nerve fibers pass through into the upper part of our nose, allowing us to smell.
Some important things to note about the cribriform plate: as the thinnest part of the skull, it can break easily from facial injuries. The break can lead to a damaged sense of smell due to cut olfactory nerves or bruised olfactory bulbs. The protective layer over the cribriform plate is thin and sticks to the bone tightly; therefore, any break in the bone can tear this layer, leading to leakage of brain fluid into the nose. Once this layer is torn, the person could experience complications such as air in the brain, brain tissue protrusion, and rising infections that could result in meningitis, a dangerous brain infection.
Quick examination and diagnosis can pave the way for early treatment and lower the risk of these potentially fatal complications. Diagnosing broken cribriform plates and leaks in the protective layer can be challenging; hence, doctors need to be particularly vigilant when examining a patient with facial injuries to ensure early diagnosis and prevention of serious complications.
What Causes Cribriform Plate Fractures?
The cribriform plate, a part of the face, typically breaks due to a strong, direct hit to the face, accounting for around 80%-90% of such injuries. Usually, it takes a substantial front-facing blow to cause this kind of crack in the cribriform plate. In most cases, this kind of break doesn’t happen alone, and is commonly accompanied by fractures in other parts of the face. Because of this, the exact reasons behind isolated cribriform plate fractures aren’t fully known.
Generally, midface fractures in adults are most often caused by car accidents, which constitute about two-thirds of all cases. Assault is the second most frequent cause at 21%, followed by falls, which account for 9% of cases. Work-related and sports injuries form a smaller chunk of cases.
In young kids, midface fractures are more often due to accidental falls. For kids between the ages of 11 to 14, sports-related injuries are more prominent, while in the age group of 15 to 18, assault is the most common cause. Other reasons for cribriform plate fractures may encompass injuries from incidents like gunshot wounds and less common are complications from medical procedures. Notably, cribriform plate fractures can occur singly as a result of complications during sinus surgery. That said, cerebrospinal fluid leak, a complication which may occur after this fracture, is reported to occur less than 1% of the time in such cases.
Risk Factors and Frequency for Cribriform Plate Fractures
Naso-ethmoid fractures, or breaks in the bone between the nose and the eye sockets, make up 5% to 15% of all facial fractures. These injuries usually occur more in men than in women, with a ratio of 3 to 1. They are most common in people between the ages of 21 and 30. Cultural and socioeconomic circumstances may affect these numbers.
The most common reason for these fractures is traffic accidents, with motorcycle accidents carrying a particularly high risk. Also, alcohol usage is strongly linked to these types of injuries. In a study of 200 people with midface fractures, it was found that one-third of them had consumed alcohol before their accident.
- Naso-ethmoid fractures form 5% to 15% of all facial fractures.
- Men are three times more likely to have these fractures than women.
- They are most common among people aged 21 to 30.
- Traffic accidents, especially motorcycle accidents, are the main cause.
- About a third of those with midface fractures had been drinking alcohol before their injury.
Signs and Symptoms of Cribriform Plate Fractures
If someone has suffered a major injury to their face, they need a thorough check-up following established medical guidelines for serious injuries. The first task the medical team should do is to identify and treat life-threatening injuries. This involves checking the person’s airway, breathing, and circulation, while also controlling any bleeding. It’s important to protect the person’s neck to prevent any spinal injuries. Injuries to the face can distort its shape, cause breathing problems, or present the risk of choking. If doctors suspect the person’s airway might be blocked, they might decide to place a tube in their throat to help them breathe. Doctors will also check the person’s mental state, and if it’s very poor, they will also need to place a breathing tube.
Once all immediate threats to life have been addressed, doctors will then conduct a more detailed body-wide examination. The head will be checked for any signs of injury such as bruising, cuts, or fractures to the base of the skull, identified as a ‘raccoon eyes’ sign or ‘Battle sign.’ A skull base fracture may also be suspected if clear or bloody fluid is leaking from the nose or ears; specifically, clear discharge from the nose could indicate a serious fracture.
Doctors will try to gather as much information as possible from the injured person, medical personnel, family members, or bystanders. Information about how the injury occurred, the person’s previous health conditions, and specifics about car accidents, for example, will be sought. People who are able to communicate will be asked about symptoms like headaches, nausea, vomiting, or changes in consciousness, as these could indicate a serious brain injury.
Stable patients with a fracture in a certain part of the skull typically have pain in the middle of the face and a nosebleed after the injury. These patients need a detailed examination of their head, neck, face, ears, nose, and mouth. However, if the nosebleed stops but clear discharge from the nose continues, this is a worrying sign of a persistent leak of brain fluid after the injury.
Testing for Cribriform Plate Fractures
If a doctor suspects that the cribriform plate, a thin part of the skull, might be fractured, they will typically prefer to use a computed tomography (CT) scan for diagnosis. This type of head and face scan should ideally be high resolution, detailed down to 1 millimeter slices, and should cover different views of the head: side (sagittal), front (coronal), and horizontal slice (axial).
The filter test, also known as the “double halo” sign, is sometimes used to identify cerebral spinal fluid (CSF) in blood secretions. The test works by observing blood and CSF on filter paper. The CSF spreads outward while the blood tends to move inward giving the appearance of two halos. However, this test, while simple and quick, has not proven to be very accurate in detecting CSF. As a result, more diagnostic studies may be needed if a CSF leak is suspected.
If available, samples of nasal and/or ear secretions should be taken and examined for beta trace protein and beta-2-transferrin. Beta trace protein is typically found in high concentrations in CSF, and Beta-2-transferrin is found in CSF, fluid within the eye, and perilymph (fluid in the inner ear). A positive test for these two substances can be a strong indicator of a CSF leak.
Treatment Options for Cribriform Plate Fractures
All patients with fractures at the base of the skull should be admitted to the hospital for monitoring and possible surgical treatment. The decision on how to treat a fracture in a certain area of the skull, the cribriform plate, largely depends on the patient’s level of consciousness and any additional injuries in the brain.
Patients who are conscious enough to score over 8 on the Glasgow Coma Scale, a scoring system used to assess level of consciousness, are usually treated conservatively. A common side-effect of these kinds of fractures is a cerebrospinal fluid (CSF) leak, which often resolves itself within a week. If needed, a procedure called a lumbar drain may be carried out to reduce pressure on the brain and help this healing process.
However, a small number of these leaks may last for several months. If a patient is less conscious (with a Glasgow Coma Scale score of less than 8), or if the leak persists for more than a week, surgery is usually the chosen treatment. This is because leaks lasting over a week increase the risk of developing bacterial meningitis, a serious infection of the brain’s protective membranes.
Endoscopic repairs – where surgery is performed through a small camera inserted into the body, have proved highly successful in treating the CSF leaks, solving the problem in over 95% of cases without the need for further treatment. But for fractures in parts of the cribriform plate that are hard to reach with an endoscope, open surgery may be needed. If this approach is taken, it’s vital to avoid pulling on the frontal lobes of the brain in order to protect the sense of smell and prevent ‘frontal lobe syndrome’, a range of potential psychological effects caused by damage to this area of the brain.
In some cases, a procedure known as an anterior subcranial approach may be used to avoid the need for pulling on the frontal lobes during surgery. On rare occasions, a more invasive procedure called an anterior craniotomy may be needed.
Currently, there’s not enough research to support the routine use of preventive antibiotics for fractures in the cribriform plate. However, many clinics will treat patients with an active cerebrospinal fluid leak with antibiotics.
What else can Cribriform Plate Fractures be?
If someone has a fractured cribriform plate, which involves a serious kind of injury, they should also be checked for any other related harm. This could include potential brain injuries from the trauma, internal bleeding inside the skull, and other broken bones in the face.
What to expect with Cribriform Plate Fractures
The future health outcomes for those with a cribriform plate fracture depend greatly on how the patient was initially affected and whether they have other injuries at the same time. If patients initially come in with a Glasgow Coma Scale (GCS) score above 8 and don’t need surgery, they generally have a good prognosis, and cerebrospinal fluid (CSF) leaks usually heal on their own.
The outlook for a cribriform plate fracture alone is typically good. Any complications, health problems, or death related to this kind of fracture often come from other injuries that the patient has, rather than the fracture itself.
Possible Complications When Diagnosed with Cribriform Plate Fractures
One of the common complications of a cribriform plate fracture is anosmia, which is a loss of the sense of smell. This happens when the nerves related to the sense of smell, or the olfactory bulb, get damaged. The loss of smell can either be partial or complete. If a surgical repair is needed, the way it’s done can help reduce the chance of further damaging the smell-related parts and resulting in anosmia.
People who had cribriform plate fractures are at a higher risk of getting infections that move up from the lower parts of the body and bacterial meningitis, an infection of the fluid and lining around the brain and spinal cord. This risk is even higher if there’s a leak of cerebrospinal fluid (CSF), the fluid around the brain and spinal cord. It’s been noted that this risk of getting meningitis is particularly high in cases where the fractures happened over a year ago.
One particular study found that in children who had cribriform plate fractures, the bacterium S. pneumoniae caused most of the meningitis cases. Due to this finding, they suggested that children with a CSF leak should get the pneumococcal vaccination.
Another problem that may occur if a cribriform plate fracture has an ongoing CSF leak is a syndrome where a person gets headaches, which get worse when standing up and better when lying down. This syndrome has similarities to the headache that can occur after a dural puncture, and it happens for the same reason—that is, decreased pressure inside the skull.
In cases where someone has a cribriform plate fracture and trauma to the middle part of the face, doctors must check for a nasal septal hematoma, where blood collects under the lining inside the nose. A nasal septal hematoma that’s not diagnosed could lead to the cartilage in the septum not getting blood supply and dying. This could result in a saddle nose deformity, giving the nose a collapsed or creased look.
For those with midface trauma, it’s not advised to put a tube into the nose and windpipe for breathing or the stomach for feeding. This is due to the risk that the tube could be accidentally passed up into the brain area via a fractured cribriform plate.
Preventing Cribriform Plate Fractures
The best way to prevent cribriform plate fractures, or specific types of skull fractures, is by taking actions to lower the chances of severe face injuries. This can include wearing protective headgear and face masks while participating in high-impact sports. It’s also very important for parents to understand the proper use of seat belts and car seats that are suitable for their children’s age, because these can significantly decrease the risk of face injuries if a car accident occurs.
Avoiding situations that could cause small children to fall, as well as implementing effective safety measures, can also be beneficial. Lastly, community efforts to reduce violence and prevent incidents of assault could play a substantial role in decreasing the cases of cribriform plate fractures.