What is C1 Fractures?
The craniocervical junction is the area where your skull and neck meet, made up of the occiput (the back part of your skull), as well as the first two bones in your neck, C1 (also known as the atlas) and C2 (known as the axis). The atlas sits just beneath the occiput, acting as a bridge between your skull and neck. It connects to the axis and the occipital condyles (projections on the skull) to allow the movement and flexibility in the neck.
The joints between these bones are responsible for half of the bending forward and twisting movements in the neck. Because of their high capability for movement, these bone segments are often injured in adults, especially risk of fractures. While fractures in the atlas bone don’t usually need surgery, it’s very important to identify and treat them quickly. A fracture in the atlas deserves a detailed check for damage to the ligaments, the connective tissues, between these bones.
The atlas bone is different from other bones in the spine. It doesn’t have a main body or a pointed projection at the back. Instead, it has a ring shape made up of a front and back arch that surrounds the spinal cord. It also has two lateral masses, one on each side, which join the arches. The top part of these masses connect to the skull to form a joint and the bottom part forms a highly movable joint with the axis.
This joint is stabilized by three ligaments: one at the front (between the front ring of the atlas and the axis), one behind the tooth-like projection on the axis, and one at the back (between the back ring of the atlas and the axis). The most important of these is the one behind the tooth-like projection, vital for the movement between the atlas and the axis. Because of its unique structure and the way it connects to the base of the skull, the atlas allows almost half of the bending and straightening movements in the neck.
What Causes C1 Fractures?
C1 fractures usually occur due to pressure straight down on the head, often combined with bending, stretching, or twisting movements, resulting in specific fracture patterns. This area experiences a lot of stress due to the weight and size of the head. In older people, these fractures can occur from minor injuries, while in younger people they are often caused by high-impact injuries.
Risk Factors and Frequency for C1 Fractures
C1 fractures, or breaks in the first cervical vertebra of the spine, make up about 10% to 13% of all cervical spine fractures. This type of injury has seen a significant increase in recent years, with older patients experiencing a nearly 700% rise. These fractures tend to happen most often in two age groups: around 30 years old and 80 years old. Nevertheless, most C1 fractures occur in people aged 50 or older. As our population continues to age, the median age of those affected by C1 fractures is also gradually rising each year. It’s also important to note that only one-third of C1 fractures happen in isolation, meaning without other associated injuries. Frequently, a fracture to the second cervical vertebra, or C2, accompanies a C1 fracture.
- C1 fractures make up about 10% to 13% of all cervical spine fractures.
- The annual incidence in older patients has shot up by almost 700%, estimated at 157 per million.
- There are two common age groups for these fractures: around 30 years old and 80 years old.
- Most cases happen in individuals aged 50 or over.
- As the population ages, the median age of people with C1 fractures increases annually by 2.6.
- Only one-third of all C1 fractures occur without other associated injuries, most often with a fracture to the C2 vertebra.
Signs and Symptoms of C1 Fractures
C1 fractures are mainly caused by severe impact to the head, often from accidents like diving into shallow water, tackles in football, or car crashes that result in a blunt force to the head. Some people, particularly those with osteoporosis or neuromuscular diseases, may be more susceptible to such fractures, even from less intense incidents.
The first step in evaluating someone for potential C1 fractures is to ensure their airway, breathing, and circulation – often summarized as “ABCs” – are functioning normally. Any needed interventions, like inserting a breathing tube, must be carefully conducted to prevent causing any further harm to fractured or dislocated bones. Once a patient is stabilized, a detailed neurological evaluation is next. This begins with an assessment called the Glasgow Coma Scale and would also include a comprehensive check for injuries to other organs based on the standard trauma protocol known as the Advanced Trauma Life Support.
A thorough physical examination for possible C1 fractures would note any pain in the neck or visible signs of trauma to the cervical spine. Other important aspects of this checkup include reviewing all cranial nerves as well as conducting a complete sensory and motor evaluation of the arms and legs. For patients showing signs of neurological shock, procedure recommends a rectal exam and testing specific nerve reflexes.
- Pain in the neck
- Visible signs of the cervical spine injury
- Review of all cranial nerves
- Sensory and motor examination of the arms and legs
- Rectal exam and nerve reflex test for signs of neurological shock
Typically, a person with a C1 fracture experiences neck pain but does not initially show signs of neurological problems. However, as this type of fracture is located near the lower part of the brain, it can potentially affect cranial nerves VI to XII, causing their respective paralysis. Fractures involving this area are also at risk for injuring the vertebral artery, which in turn can lead to inadequate blood supply to certain parts of the brain. Thus, a complete neurological examination involving the cranial nerves is essential.
Testing for C1 Fractures
Among all atlas fractures (fractures of the first vertebra in your neck), the Gehweiler type 3 classification is the most commonly seen.
The Rule of Spence is a guideline that helps doctors understand neck injuries better. It suggests that if the side parts of the vertebra (known as the lateral mass) shift more than 6.9 mm, it’s likely that the transverse atlantal ligament (TAL – a key stabilizing element in the neck) is ruptured. If this shift is greater than 8.1 mm, it is even more likely that the TAL is injured.
Other warning signs of a TAL injury include a larger than normal gap (more than 3 mm in adults and 5 mm in children) between the atlas and the tooth-like dens of the second vertebra on X-rays taken from the side when the patient is in you functional (normal) position. Also, a C1:C2 ratio greater than 1.10 on plain X-rays can hint at a damaged transverse ligament.
Those with other spine injuries, a larger than normal atlanto-dental gap, or significant lateral mass displacement are at high risk of injuring their vertebral artery. It’s crucial to pay particular attention to how the blood vessels are positioned relative to the atlas in these patients. If the break involves the part of the vertebra that extends sideways (the transverse process) or the lateral mass, it could significantly increase the risk of a vertebral artery injury.
Treatment Options for C1 Fractures
When it comes to treating fractures of the C1 vertebra in the neck, several strategies exist. These include primary surgery (surgery as the initial treatment), secondary surgery (surgery after non-surgical methods have failed), and non-surgical methods that use external devices to stabilize the neck.
Factors such as injuries to the lower neck often influence the choice for surgery. Some kinds of C1 fractures, like Gehweiler types 1, 2, 3b, or 5 fractures, are typically stable and can be treated without surgery. In these cases, a patient might wear a brace or cast for around 8.5 weeks.
However, over time, patients may experience issues like a worsening gap at the fracture site or dislocation of the joint. Ongoing imaging can help identify these problems. An MRI scan is essential to differentiate between stable and unstable type 3 injuries.
Unstable type 3b fractures and type 4 fractures are usually treated surgically. In these surgeries, screws are placed into specific parts of the spine to stabilize it. Several techniques exist, each involving different placements of screws.
Using ‘neuronavigation’, a kind of advanced imaging technology, can help place the screws accurately and reduce radiation exposure. On the downside, this system can be expensive and requires practice to use effectively. A CT scan can then be used to check the accuracy of the screw placement. In a study, over 97% of screws were placed satisfactorily, and no significant injuries were associated with the misplaced screws.
After surgery, wrist movement may be reduced due to the fusion of the upper spine. Alternatively, an anterior C1-ring osteosynthesis via systems like the Jefferson-fracture reduction plate (JeRP) can help maintain neck movement while also improving bone union. This system also helps maintain the integrity of the neck and restore its normal height.
The JeRP system is mainly used for unstable C1 fractures with or without transverse atlantal ligament (TAL) injury. It’s proven to be better than C1-C2 fusion in improving neck pain and movement. Furthermore, it’s been shown to significantly reduce surgery time, blood loss, radiation dose, hospital stay, and cost.
What else can C1 Fractures be?
In children, it’s very important to tell the difference between a broken bone in the top vertebra (C1) of the neck, and parts of the bone that haven’t fully developed yet. Typically, these parts, known as ‘ossification centers,’ start to show when a child is around one-year-old. There are usually three of these ossification centers in the neck vertebra.
Additionally, in a child’s neck bone, there is a place called ‘neurocentral synchondrosis,’ which connects the front and back arches of the vertebra; this usually fuses together around the age of seven. Moreover, the back arch normally closes around when the child turns three. It’s important to remember that these in-progress bone formations in children aged six years or younger can appear like fractures, especially if the child has had an injury to their neck.
What to expect with C1 Fractures
Generally, C1 fractures have a good outcome. They are usually treated with conservative methods and external immobilization, which are often enough to heal the fracture effectively. It’s also worth noting that C1 fractures rarely result in any neurological deficits due to the way the fracture fragments displace outwards, thus avoiding encroachment on the neural canal. Also, the spinal canal is quite wide at this level.
However, the healing progress and prognosis of these fractures greatly depend on whether they are accompanied by bone and ligament injuries, especially those involving the transverse ligament.
Possible Complications When Diagnosed with C1 Fractures
Osteosynthesis, a surgical procedure to fix a bone fracture, has certain complications. It may be challenging to fix fractures if they’re deep within narrow spaces. Also, the screw end can potentially damage the posterior part of the throat, which can lead to complications such as wound issues or postoperative swallowing difficulties.
Posterior instrumentation, another surgical procedure, has its own set of complications, which may include leakage of cerebrospinal fluid, blood clot formation in and around the cerebellum, injuries to major arteries, heavy bleeding, an air clot in the veins, and complications with the hardware.
About 6% of the time, additional surgery is needed, mostly because of infection at the surgical site or instability.
A study mentioned that in the month following surgery, about a 12.2% of mortality rate was reported. Increased age and a higher Charlson Comorbidity Index, which measures underlying patient health, corresponded to a higher risk of death. On a positive note, those with an additional C2 fracture (a specific type of neck fracture) showed an improvement in survival rates.
Here are the potential complications:
- Difficulty fixing fractures in narrow spaces
- Damage to the throat wall
- Wound complications
- Postoperative swallowing difficulties
- Leakage of cerebrospinal fluid
- Blood clots in and around the cerebellum
- Injuries to major arteries
- Heavy bleeding
- Air clot in the veins
- Hardware complications
- Surgical site infection
- Instability, necessitating additional surgery
- Increased risk of death due to older age or high Charlson Comorbidity Index
Recovery from C1 Fractures
When a halo device is used, regular x-ray checks are needed to confirm that the bone is healing properly. Typically, the halo device needs to be worn for between 8 and 16 weeks, but this can vary depending on how quickly the fracture is healing. After the halo device is taken off, the patient is given a collar to wear and should start a rehab program to help regain their muscle strength.
Preventing C1 Fractures
Most C1 fractures, which are a kind of neck injury, are usually handled non-surgically with a device that keeps the neck stable. Patients should understand that they need to regularly check in with their doctors and there might be a chance of needing surgery if the non-surgical treatment does not work. Smoking can slow down the healing of the fracture, so it’s very important not to smoke. It’s also highly recommended for patients to wear their neck collar consistently to promote proper healing of the fracture.
