From the Guidelines
A standard head CT typically visualizes the upper cervical spine, including the first two cervical vertebrae (C1 and C2), and sometimes portions of C3. The atlantooccipital joint and atlantoaxial joint are usually well-visualized 1. However, the exact extent of cervical spine visualization depends on the specific scanning protocol and field of view used. Some key points to consider when evaluating the cervical spine on a head CT include:
- The primary purpose of head CT is to evaluate intracranial structures, not the cervical spine, so complete cervical spine assessment requires dedicated cervical spine imaging.
- The addition of cranio-cervical junction CT will detect injuries not revealed by plain films in approximately 10% of patients scanned 1.
- Scanning the entire cervical spine in blunt polytrauma detects significantly more injuries than plain films or directed scanning 1. The limited visualization of the cervical spine on a standard head CT is important to recognize because significant cervical spine injuries can exist below the visualized levels. For this reason, if cervical spine injury is suspected, a dedicated cervical spine CT or other appropriate imaging should be obtained to evaluate the entire cervical spine from C1 through C7 and the cervicothoracic junction.
From the Research
Cervical Spine Visualization on CT Scans
- The portion of the cervical spine visualized on a computed tomography (CT) scan of the head can vary, but studies suggest that the upper cervical spine, including the first three cervical vertebrae (C1-C3), can be visualized with minimal additional time and cost 2.
- One study found that adding a few more slices to the routine head scan protocol to cover the first three cervical vertebrae demonstrated four upper cervical fractures that could not be seen on plain films, even in retrospect 2.
- Another study recommended that practice guidelines include the use of helical CT scan of the entire cervical spine as the diagnostic procedure for those blunt trauma patients undergoing CT scanning of the head, as it increased the accuracy of detecting cervical spine injury from 54% to 100% 3.
Limitations of CT Scans
- However, other studies have noted that CT scans may not always be able to visualize the entire cervical spine, particularly in comatose patients, and that bedside fluoroscopic flexion and extension studies may be inadequate for visualizing the lower cervical spine 4.
- In some cases, CT scans may miss subtle alterations such as dens tilting, double cortex sign, lateral subluxation of C1, and prevertebral soft tissue swelling, which can be indicative of fractures 5.
Clinical Relevance
- The use of CT scans in evaluating cervical spine trauma is crucial, as it can provide information to help direct patient care, including diagnosis, next steps in treatment plan, and prognosis 6.
- The clinical relevance of imaging findings to clinical outcomes in the setting of spinal cord injury is an area of ongoing research, with advancements in CT processing, imaging sequences, and techniques aiming to increase sensitivity for detection of pathology and decrease imaging and interpretation time 6.