[Upper cervical spine fracture: sources of misdiagnosis]

Missing cervical spine fractures during the initial plain film study may lead to severe neurological complications for patients and to medicolegal responsibilities for the physician. The upper cervical spine tract (C1-C2) is considered to be at high risk for misdiagnoses. We decided to investigate the possible causes of mistake in the cases of missed fractures on the initial plain film, performed in the emergency room.

We retrospectively reviewed the radiological reports, the original plain films and the CT findings, of 32 patients with upper cervical (C1-C2) fractures, admitted January 1994 to December 1998. Twenty-eight of these patients (87.5%) had multisystem trauma, 4 (12.5%) had minor craniocervical trauma. None of these patients had neurological signs correlated to the cervical injuries, 30 of them had normal consciousness and reported only neck pain, 2 of them were unconscious for the associated head trauma and were hospitalized in the intensive care unit. All the patients with normal consciousness underwent conventional three-view cervical spine radiography; the two unconscious patients in the intensive care unit were submitted to bedside examination with an anteroposterior and a lateral views of the cervical spine. All patients underwent spiral CT of the upper cervical tract.

In 9 of 32 patients (28%) a cervical fracture was missed on the plain film and CT was performed only because of persistent neck pain. We found 2 Jefferson's fractures, 2 type II dens fractures, one type I dens fracture and 4 hangman's fractures. In 8 of the 9 patients (89%) the fracture was potentially unstable. Misdiagnoses resulted from overlapping bone structures (3%), suboptimal film quality (3%), satisfaction of search phenomenon (3%), missed mild tilting of the dens (6%), missed double cortex sign (16%), missed C1-C2 lateral subluxation (6%) and marked osteoporosis (3%). Prevertebral soft tissue swelling was not seen in any of the 9 cases of missed fractures. Considering the group of patients with C1-C2 fractures separately, the false negative rate is 28%, which corresponds to 10.7% of the total number of patients with cervical fractures and dislocations examined during the same period.

Among the causes of false-negative interpretation, osteoporosis, suboptimal film quality due to associated fractures and overlapping bone structures must be considered unavoidable. On the other hand these possibilities should be indicated on the X-ray report because, if painful symptoms persist, a CT exam is strongly advised. Subtle alterations like dens tilting, double cortex sign, lateral subluxation of C1 and prevertebral soft tissue swelling should be regarded as highly suspicious for fracture. Missing these lesions might be considered a true diagnostic mistake with possible legal consequences, which may also expose the patient to the risk of neurological complications. The satisfaction of search phenomenon can be avoided only by trying to use a search pattern for every film, which includes checking all the visible anatomical structures even in the presence of a particularly evident lesion. In all questionable cases or high-risk fracture patients, even with an apparently negative plain film, it is advisable to perform CT instead of additional plain films. Finally, in all the patients treated in the intensive care unit for head trauma, an upper cervical CT scan should be routinely carried out at the same time as the brain scan.