The signal intensity of the normal odontoid process (dens) displayed on magnetic resonance images

In order to analyse the normal signal intensity of the medullary space of the odontoid process (dens) relative to age, the craniovertebral junction of 33 asymptomatic volunteers in six age groups was examined by means of magnetic resonance imaging. To avoid partial-volume effects 3-mm slices were used in sagittal and axial planes. The signal intensities relative to cerebral white matter varied from 0.51 to 1.23 in the sagittal plane and 0.56 to 1.51 in the axial plane. The signal intensities relative to muscle varied from 0.76 to 2.40 in the sagittal plane and 0.96 to 2.30 in the axial plane. The signal intensities relative to fat varied from 0.22 to 0.62 in the sagittal plane and 0.23 to 0.68 in the axial plane. No correlation with age of the volunteers was found. The normal medulla of the dens may exhibit a low signal intensity on T1-weighted images irrespective of age.     

Interruption of the spinolaminar line at C6 and C7: a normal variant

Objective: To describe a normal variant of the lower cervical spine manifested as interruption of the spinolaminar line. Although disruption of this line is a useful sign of significant cervical spine injury, it is important to note that this finding may represent a normal variation. Conclusion: Interruption of the spinolaminar line at C6 and C7 does not necessarily represent cervical spine dislocation and/or fracture and may be a normal anatomic variant. Knowledge of this fact may prevent false diagnosis and avoid unnecessary investigation. We propose that an alteration in facet joint orientation at C6 and C7 may represent the etiology of this normal variant.     

Odontoid fractures following blunt trauma

Fractures of the odontoid process typically result from forceful blunt trauma. They often produce instability of the cervical spine, and may be associated with neurologic impairment. This study was designed to examine the epidemiology and demographics of odontoid injuries, including their incidence and prevalence relative to other spine injuries, the prevalence of associated injuries, and the likelihood of neurologic impairment. Of 34,069 enrolled blunt trauma victims, 818 (2.4 %) sustained a cervical spine injury, 94 of whom had a fracture of the odontoid. The relative prevalence of odontoid fractures varied by age, ranging from less than 3 % among individuals under age 20 years, to greater than 20 % in patients over 80 years old. Classification by Anderson–D'Alonzo criteria revealed 6 type I injuries, 60 type II injuries, and 27 type III injuries; one vertical injury could not be categorized. Over half of the odontoid fracture victims sustained additional cervical spine injuries, with 90 % of these injuries involving the atlanto-axial complex. In addition, non-spine-related injuries were found in 52 % of odontoid injury victims, over one-third (34 %) presented with an altered level of alertness, and almost one-quarter (23 %) exhibited some form of focal neurologic deficit associated with their injury. Fractures of the odontoid are among the most frequently encountered cervical spine injuries, and increase in prevalence with increasing patient age. Odontoid fracture victims often have other spine injuries, particularly to the atlanto-axial complex, and may harbor other non-spine-related injuries and neurologic pathology.     

The role of spiral CT vs plain films in acute cervical spine trauma: a comparative study

Purpose: To compare the diagnostic yield of conventional radiographs versus helical computed tomography (CT) in screening acute trauma patients. Methods: We reviewed 604 trauma patients who presented to our level I trauma emergency room and underwent both conventional radiography and spiral CT of the cervical spine of. Results: Of the 604 patients, 30 (5.13 %) had fractures seen on helical CT, only 10 of which were diagnosed on conventional radiography. Conclusion: In the screening of acute trauma patients, conventional radiography is less sensitive in detecting fractures than helical CT. CT should therefore be considered as a standard modality choice in such cases.     

Improving the cervical spine X-ray in trauma patients utilizing dynamic range compression (DRC) modified digital radiography

Purpose: Inadequate cervical spine X-rays delay diagnosis and treatment and add radiation exposure to trauma patients with suspected cervical spine injury. Digital radiography (DR) with dynamic range compression (DRC) modification can improve the visualization of abnormalities in the cervical spine X-ray. Methods: Two digital hard copy cervical spine X-rays from each of 65 trauma patients were used, both with standard DR processing, and with the second image having the DRC algorithm applied. Blinded readers from emergency medicine, surgery, radiology, and critical care specialties evaluated the films with data analyzed by Student's t-test and ϰ²; P < 0.05. Results: Readers cleared more of the DRC than of the non-DRC images: 41 % vs 30 %, P < 0.001. More vertebral bodies were visualized on DRC than on non-DRC images: 65 % vs 53 % showing C7, P < 0.001. For overall impression of the image quality, DRC images rated higher on a 10-cm visual analog scale than non-DRC: 6.7 vs 4.2, P < 0.001. Conclusions: DRC modification of DR images enabled physicians to evaluate cervical spine X-rays more rapidly and accurately after trauma, requiring fewer repeat films.     

Normal cervical spine variations mimicking injuries in children

Evaluation of the cervical spine is a constant problem. This communication deals with the various normal variations and congenital anomalies that are frequently misinterpreted for traumatic lesions. Emphasis is on how to identify these anomalies and how to differentiate them from traumatic injuries of the cervical spine.     

Should an MR scan be performed routinely after a normal clearance CT scan in the trauma patient? Experience with 59 cases

Magnetic resonance (MR) imaging is not routinely used to exclude ligamentous and other soft tissue injury in the unconscious trauma patient. In order to determine the frequency and types of soft tissue injuries detected by MR imaging but not by computed tomography (CT), we performed a retrospective investigation comparing the MR findings in 59 trauma patients, either alert or unconscious, who previously had undergone a negative clearance multislice CT study of the cervical spine. Six patients had abnormalities not identified on the CT studies, including four cases of ligamentous injury.     

Can CT eliminate the initial portable lateral cervical spine radiograph in the multiple trauma patient? A review of 200 cases

Purpose: This investigation examines whether there is a continued role for the initial screening lateral portable radiograph in patients whose cervical spine is “cleared” by a CT examination. Methods: A retrospective review of 200 multiple trauma patients suspected of cervical spine injury (CSI) was performed. All patients had a screening lateral portable cervical spine radiograph (LPCSR) followed by cervical spine CT (CSCT). All scans were helical and included coronal and sagittal reformations. Reports of both examinations were compared for all patients. For those patients with signs of acute CSI, the two reports were compared to determine whether the LPCSR contained any information affecting patient outcome that was not detected by CSCT. Results: The CSCT showed no signs of acute CSI injury in 190 patients. Ten CSCT scans showed signs of fracture. In these 10 patients, the screening LPSCR showed signs of fracture in 1 patient, question of fracture in 2 patients, and no fracture in 7 patients. No LPCSR demonstrated significant information not seen on the accompanying CSCT. No LPSCR showed a finding that altered patient management prior to CSCT. Conclusion: The data suggest that an initial LPCSR is unnecessary if the patient is having a screening CSCT.     

CT scan patterns of articular mass injuries of the lower cervical spine

Traumatic lesions of the cervical articular mass are infrequent, are potentially unstable and often require internal fixation. Standard X-rays and CT images can be difficult to analyze in an emergency situation. Standard X-rays must always be performed first, but CT, particularly helical CT, is the definitive imaging modality. Two-dimensional reformations are performed in all cases, together with 3-D reformations when indicated. We here present a simple and logical analysis based on the normal pattern of the interfacetal joint, which is always made of two pieces of bone, and only two, in a precise order. Post-traumatic deviations from this normal pattern reflect an injury, and there exists an accurate correlation between the CT pattern and the pathologic features.     

Improving the imaging diagnosis of cervical spine injury in the very elderly: implications of the epidemiology of injury

Purpose: To enumerate host and vector factors that affect each phase of cervical spine injury (CSI) among the elderly, and to attribute specific pathoanatomic characteristics of CSI to host and/or vector factors. Methods: Structured review of English literature references selected from MEDLINE keyword search using PUBMED and OVID search engines. Only articles addressing the role of “aging” or being “elderly” (using a variety of definitions) in CSI were included. The following information was abstracted: journal; year of publication; authors' specialty or departmental affiliation; study design; inclusion and exclusion criteria; year(s) of data collection; number of CSI vs. controls; summary findings, including rate estimates, obvious study weaknesses. Results: Seven of 13 articles were medical-record-based case series, most derived from institutional trauma registries. Four were population-based surveys. One was an assessment of Medicare claims data for all-cause trauma and one a review paper. Blunt-force CSI was most commonly related to domestic falls, then to vehicular-pedestrian collisions and finally to vehicular crashes. More than two-thirds of fractures involved CO-C3, especially in individuals with cervical spondylosis and/or osteoporosis. In 15 to 40 % of CO-C3 fractures there is a delay in diagnosis. An adult forme fruste of SCIWORA (spinal cord injury without radiographic abnormality) was a relatively common cause of central and anterior cord syndromes in the absence of observable fractures or dislocations. Conclusions: The epidemiology of CSI in elderly patients should inform triage and imaging decisions. Since most CSI diagnostic errors involve the upper cervical spine, additional attention to the radiographic anatomy of the craniocervical junction and diligent search for abnormalities in this region are warranted.     

The crowned dens syndrome: a rare form of calcium pyrophosphate deposition disease

The crowned dens syndrome has been termed as acute neck pain ascribed to CPPD deposits associated with a tomographic appearance of calcification surrounding the odontoid process. This rare entity resulting in cervical cord compression is generally seen in older female patients. We present a 26-year-old woman with cervical cord compression due to massive calcification in the periodontoid area and discuss the X-ray and CT findings of the disease. Received: 8 July 1999; Revised: 24 September 1999; Accepted: 12 November 1999     

Bilateral absence of the pars interarticularis of C2: developmental or post-traumatic abnormality?

A 19-year-old male was diagnosed with bilateral absence of C2 pars interarticularis incidentally after a motor vehicle accident. Plain radiography, cross-sectional CT, and 3D CT findings of this case are presented. The differential diagnosis and possible etiologies including remote child abuse are discussed in detail.     

Cervical spine injury in the very elderly

Background: Elderly patients are known to be at increased risk of cervical spine injuries. This propensity for injury becomes more important as the population of mobile elderly individuals increases. The present study seeks to examine the incidence and spectrum of spine injury among patients aged 80 years or greater, and to examine the efficacy of a decision rule for obtaining cervical spine radiography in this extreme age group. The decision rule would determine whether imaging could be avoided in patients who have none of the following: (1) posterior midline cervical spine tenderness; (2) focal neurological deficit; (3) abnormal level of alertness; (4) evidence of intoxication; or (5) clinically apparent distracting painful injury. Methods: All blunt trauma victims presenting to participating emergency departments underwent clinical evaluation prior to radiographic imaging. The elements of the decision rule were assessed and documented in each patient prior to radiographic imaging. The presence or absence of cervical spine injury was subsequently based on the final interpretation of all radiographic studies supplemented by a review of neurosurgical and risk management logs from each participating hospital. Data on all patients aged 80 years or greater were sequestered from the main database for separate analysis. Results: The study enrolled 34,069 individuals, including 818 patients (2.4 %) with cervical spine injuries. This population contained 1,070 patients (3.1 % of all cases) aged 80 or greater, 50 of whom (4.7 %) sustained cervical spine injuries. Injuries to the craniocervical junction (particularly C2 and the odontoid) accounted for 47.3 % of the injuries in the elderly, but only 28.6 % of injuries in younger patients. Older fracture victims were also likely to have more injuries (2.54 injuries/patient) than their younger counter parts (1.78 injuries/patient). The decision rule correctly identified all very elderly cervical spine injury victims [sensitivity 100.0 %; confidence interval (CI) 92.9–100.0 %], and designated 132 patients as “low-risk,” yielding a negative predictive value of 100.0 % (CI 97.3–100.0 %). Conclusions: The very elderly are at increased risked of cervical spine injury, particularly injury to the craniocervical junction. They also tend to have more extensive injuries than younger patients. Despite the increased risk of injury, the decision rule performed well in the very elderly, and allowed correct identification of all cervical spine injury victims.     

Atlantoaxial instability associated with an orthotopic os odontoideum: a multimodality imaging assessment

Radiography, computed tomography (CT), and magnetic resonance imaging exams of the cervical spine were performed in a 29-year-old man who was ultimately diagnosed with an orthotopic os odontoideum during admission for injuries sustained in a motor vehicle collision. Initial radiography suggested either os odontoideum or an acute fracture of the dens. Further imaging with CT and flexion and extension radiographs confirmed os odontoideum and excluded a dens fracture. Although rare, os odontoideum is an important cervical spine anomaly to consider and to distinguish from an acute fracture of the dens.     

Cervical spine injury: accuracy of helical CT used as a screening technique

Objective: The study objective was to determine the sensitivity and specificity of a helical CT technique to screen for cervical spine injury in a high-risk trauma population. Materials and methods: The helical CT reports for a consecutive series of 601 high-risk adult blunt trauma victims were reviewed. Findings were confirmed using an independent reference standard, which consisted of additional cervical spine imaging (CT, MRI, or radiography), operative findings, autopsy results or clinical outcome. Results: Sensitivity and specificity of helical CT for injury were 77/81 (95 %; 95 % confidence limits: 90–100 %) and 484/520 (93 %; 95 % confidence limits 91–95 %) respectively. Four false negative cases were comprised of three missed ligamentous injuries and one missed fracture. False positive cases (n = 36) were mostly attributed to possible facet fracture (n = 6), possible ligamentous injury (n = 8) or technically inadequate scan (n = 6).The overall accuracy of the helical CT protocol for cervical spine injury in this population was 561/601 (93 %; 95 % confidence limits 91–95 %). Conclusion: Helical CT has high accuracy for cervical spine injury. We believe that helical CT should be the preferred imaging strategy in high-risk blunt trauma patients.     

Occult and secondary injuries missed by plain radiography of the cervical spine in blunt trauma patients

Background: Plain radiography does not visualize every cervical spine injury sustained by blunt trauma victims. The purpose of this study was to examine the prevalence and types of injuries missed by plain radiographs of the cervical spine and determine how frequently such radiography fails to detect any cervical spine injury. Methods: Images from all radiographic studies performed on blunt trauma victims presenting to 21 participating institutions were reviewed to compile an exhaustive list of all CSIs sustained by each individual. These injuries were then compared with the injuries detected by plain radiography alone. Patients were classified as having a “sentinel” injury if one or more of their injuries were visible on plain radiographs. Patients were classified as having a radiographically “occult” injury if none of their injuries were visible on plain radiographs. The number and types of injuries missed on plain radiographs were then separately tabulated for the sentinel and occult injury groups. Results: Plain radiographs were completed in 570 of 818 victims of acute cervical spine injury and revealed 702 of 1,056 injuries. Plain films failed to detect 98 occult injuries present in 60 patients (10.5 %), and failed to detect 256 secondary injuries in 510 patients (89.5 %) who had a sentinel injury identified. Plain radiographs failed to reveal 79 of 136 (58.1 %) lateral mass injuries and 67 of 105 (63.8 %) lamina injuries, making these the most frequent sites of missed injury. Conclusions: Plain radiographs frequently fail to reveal injuries to the cervical spine, particularly those involving the lamina and lateral mass. The majority of the missed injuries represent secondary injuries in patients with a sentinel injury identified on these films. However, plain films fail to detect any injury in a minority of injured patients.     

Imaging of cervical spine trauma: are the anteroposterior and odontoid radiographs needed when CT of the entire cervical spine is routine?

Objective: To evaluate the contribution of the anteroposterior (AP) and odontoid radiographs in cervical spine trauma when helical CT of the entire cervical spine is performed in routine screening. Methods: In part 1 of the study, 47 patients with cervical spine fracture (positive) and 92 patients without fracture (negative) were retrospectively assembled into a study population. For each patient, the lateral radiograph and the CT were evaluated for the presence or absence of fracture. The results were compared to the radiology report at the time of injury which was based on the lateral, AP, and odontoid radiographs plus the CT (gold standard). In part 2 of the study, the individual sensitivities of CT and each radiograph were determined by review of the 47 positive patients with the fracture locations known a priori. Results: In all 47 positive patients, the presence of fracture was correctly identified using only the lateral radiograph and the CT. In none of the 92 negative patients was the lateral radiograph plus CT incorrectly interpreted as positive for fracture. The sensitivities for fracture of CT, the lateral radiograph, the AP radiograph, and the odontoid radiograph were 100, 47, 28, and 18 % respectively. Conclusion: The AP and odontoid radiographs did not contribute to the evaluation of suspected cervical spine fracture when the lateral radiograph and helical CT of the entire cervical spine were performed in routine screening.     

Anterior subluxation of the cervical spine

Anterior subluxation (AS), or hyperflexion sprain, generates a disproportionate level of concern in emergency medicine. Anxiety related to this injury arises from the fact that AS may produce delayed mechanical instability of the cervical spine, with resultant pain and neurological impairment. Furthermore, its radiographic presentation may be very subtle, and it may be impossible to reliably diagnose or exclude this injury using standard screening radiographs. Additional studies, such as flexion–extension (FE) radiography and magnetic resonance (MR) imaging, are often used in the acute setting to assess injury status and radiographically exclude AS injury. There are a number of reasons to discourage this latter practice, which can represent an impossible attempt to “radiographically clear the cervical spine” of blunt trauma patients with “100 % certainty.” This is because AS is an uncommon lesion, and the neurological deficits secondary to delayed instability are almost always minor and transient. Furthermore, AS is usually not entirely occult on screening plain films (which are typically “abnormal” even if in nonspecific ways). Finally, FE imaging, done acutely in the presence of spasm, is probably unable to exclude this diagnosis reliably, even when plain films are normal, and emergent MR, probably the most accurate technique, is not widely available. Risk stratification provides a rational alternative approach for assessing injury status. Low-risk patients may be spared further imaging provided they are given appropriate precautionary return instructions. High-risk patients require emergent evaluation by an experienced spine specialist, and may benefit from advanced imaging. Patients at moderate risk may be best managed with symptomatic treatment, warnings to avoid significant physical activity, and delayed FE imaging and evaluation by a spinal specialist. They should also be instructed to seek immediate medical attention if they develop any indications of delayed instability, including severe pain and /or neurological signs. This stratified approach not only increases the likelihood that delayed subluxation will be recognized before it leads to chronic instability, but frees clinicians and radiologists from the quixotic burden of trying to “clear” the cervical spine with 100 % certainty in the acute setting.     

Screening for cervical spine trauma with helical CT: experience with 676 cases

Purpose: CT scanners with helical capability are commonplace. Evaluation of multiple trauma patients using this technique is fast, and easily performed as part of the radiological evaluation. Our purpose was to ascertain the clinical effectiveness of cervical spine screening with helical CT in a large sample population of multitrauma patients. Materials and methods: A retrospective review was carried out using screening helical CT scans from multitrauma patients referred to the Massachusetts General Hospital emergency department. The radiographic diagnosis was evaluated and tallied along with the clinical diagnosis and outcome for each patient included in the study. Results: Six hundred seventy-six patients conformed to the inclusion criteria. In this series, 59 true-positive, 616 true-negative, 1 false-negative, and no false-positive findings were encountered. These data result in a sensitivity of 98.3 %, a specificity of 100 %, and an accuracy of 99.9 %. Conclusions: Screening helical CT in the evaluation of trauma patients has a high diagnostic accuracy, and is sensitive and specific in diagnosing clinically relevant fractures of the cervical spine.     

MR arthrography of the hip: normal intra-articular structures and common disorders

This pictorial review illustrates the anatomical features of normal intra-articular components of the hip and their common disorders on MR arthrography. On T1-weighted MR arthrograms, the normal contrast-filled joint cavity shows a homogeneous high signal intensity. Normal acetabular labrum appears as a well-delineated triangle showing a low signal intensity, surrounded by contrast material in the perilabral recess. Intra-articular paramagnetic contrast outlines labral tears, loose bodies, communicating labral cysts and cartilage lesions (traumatic tears, focal defects, degenerative fissures and thinning), and improves their detection. Overall, MR arthrography enables accurate detection and staging of hip intra-articular structure abnormalities. Received: 6 June 1998; Revision received: 2 January 1999; Accepted: 2 April 1999