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What is the diagnosis?

Concussion and moderately displaced C1 (Jefferson) burst fracture. C1 fractures should be highly suspected in patients with pain during flexion and extension. These fractures exhibit a bimodal distribution of incidence, with high-energy axial loading in early adulthood and low-energy ground level falls in the elderly [1].

The differential diagnosis for this patient’s neck pain includes omohyoid strain, cervical ligamentous strain, odontoid fracture, teardrop fracture, facet dislocation, spinal cord injury, brachial plexus injury, cervical disc herniation, atlantoaxial instability, vertebral artery dissection, and referred shoulder pain.

What is the mechanism of injury?

C1 fractures most often occur due to significant axial loading through the skull combined with rotary or flexion/extension force.

• Pearl: C1 differs from the other cervical vertebrae in that it has no vertebral body or spinous process; instead having a posterior tubercle. It is responsible for 50% of flexion-extension range of motion.

What physical exam findings are expected?

Exam findings that raise suspicion for a C1 fracture include pain with flexion, extension, and axial loading, with possible relief with axial distraction. Concomitant cervical level involvement significantly increases the risk of neurological complications. Cranial nerves should be examined, particularly CN VI and XII as they extend caudally near C1. If the fracture extends near the transverse foramina, the vertebral arteries can also be involved [2].

• Pearl: Concurrent C2 fractures have a 41-44% incidence rate in patients with C1 fractures [3].

Which imaging modalities can be used?

While lower cervical injuries are readily identified on plain radiographs, the location and surrounding structures of C1 make proper identification of fractures at this level difficult to ascertain. Diagnosis often requires CT scan, while MRI is indicated in cases of confirmed fracture to evaluate for ligamentous injury.

• Pearl: Open-mouth radiographs showing a lateral mass displacement of 7mm or more is highly suggestive of ligamentous instability.

What is the management in the ED?

Treatment is typically conservative, with operative intervention being reserved for unstable fractures with significant instability or cases of multilevel fracture. Immediate immobilization in a hard collar or pin-less halo for 8-12 weeks is typically sufficient to allow healing. Serial examination for early recognition of neurologic decline.

When do you consult a spine specialist?

Orthopedics (or other spine specialist depending on your hospital) should be consulted immediately upon diagnosis. Periodic follow-up with plain radiography to ensure ligamentous stability, as well as patient education are crucial. After the 8-12 weeks of immobilization, flexion-extension radiographs should be obtained to evaluate stability. C1 fractures with instability represent an absolute contraindication to return to contact sports, while stable C1 fractures remain a controversial but relative contraindication.