Session VI - Basic Science / Injury Prevention / Spine

Sat., 10/10/09 Basic Sci./Injury Prevent./Spine, Paper #77, 11:58 am OTA-2009

The Value of Adding MRI to CT Protocols for Cervical Spine Clearance In Blunt Trauma: A Meta-Analysis

Andrew Schoenfeld, MD1 (7-DePuy, A Johnson &Johnson Company, Stryker, Synthes);
Natalie Warholic, MA2 (n); Christopher M. Bono, MD2 (4, 5A, 7-Depuy Spine; 4-Stryker Spine; 5A, 7-Stryker; Medtronic Sofamor Danek; 5A-Life Spine; 7-Synthes Spine);
Kevin J. McGuire, MD3 (4, 5A-Globus Medical; 7-EBI); Mitchel B. Harris, MD2 (7-Synthes);
1Harvard Combined Orthopaedic Program, Boston, Massachusetts, USA;
2Brigham and Women’s Hospital, Boston, Massachusetts, USA;
3Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

Purpose: Evaluation and clearance of the cervical spine in blunt trauma patients remains a controversial and challenging topic. While CT imaging is very sensitive for identification of osseous abnormalities, it has not been found to demonstrate similar precision in detecting ligamentous injuries. MRI has been found to be sensitive in detecting cervical injury, but many authors have questioned the potential for this imaging modality to augment the ability of CT to identify clinically significant injuries. The purpose of this investigation was to quantify the ability of MRI to detect “clinically significant” cervical injuries in the setting of a negative CT scan. The hypothesis was that MRI would detect “clinically significant” cervical spine injuries despite negative findings on CT.

Methods: A computerized search was performed for studies published in the English-language literature from 2000 to 2008. Inclusion criteria were investigations of patients undergoing MRI for the purposes of cervical spine clearance following a negative CT scan; reporting of the outcome of positive MRI findings (cervical clearance, surgical intervention, prolonged use of collar, etc); reporting of statistical data to facilitate calculation of true positives, true negatives, false positives, and false negatives; and a minimum of 30 patients involved in the investigation. A true positive in this investigation was an MRI result that led to a change in management. A false positive was defined as a MRI finding that still allowed for removal of cervical spine precautions. Results of appropriate studies were then pooled and original scale meta-analyses were performed to calculate sensitivity, specificity, and positive and negative predictive values.

Results: 11 investigations met the inclusion criteria, comprising 1,550 trauma patients with negative cervical spine CT scans. Of these, MRI detected 194 abnormalities in 182 patients (11.7%). The majority of these were ligamentous injury (86) and degenerative changes, but fractures and dislocations were identified in 4 instances. In 96 cases, MRI was able to identify a clinically meaningful injury, with 84 patients requiring prolonged use of a collar and 12 patients requiring surgical stabilization. The addition of MRI to a CT protocol for cervical clearance demonstrated 100% sensitivity and 94% specificity. The positive predictive value of MRI was 53%, while the negative predictive value was 100%. The false positive rate was 6%.

Conclusions: The optimal imaging protocol for cervical clearance remains controversial. The risks of occult cervical injury must be weighed against the morbidities of prolonged immobilization. While CT is very sensitive in identifying osseous abnormalities, the results of this investigation demonstrate that this modality is not capable of detecting all clinically significant injuries. Indeed, in 6% of cases, the addition of MRI facilitated a change in treatment protocol and, in 1%, injuries requiring surgical intervention would have been missed using CT alone. Despite recent reports advocating for the use of CT imaging alone to facilitate clearance of the cervical spine, this meta-analysis supports a continued role for MRI in evaluating patients who are obtunded, or symptomatic, despite a negative CT scan.

Disclosure: (n=Respondent answered 'No' to all items indicating no conflicts; 1=Board member/owner/officer/committee appointments; 2=Medical/Orthopaedic Publications; 3=Royalties; 4=Speakers bureau/paid presentations; 5A=Paid consultant or employee; 5B=Unpaid consultant; 6=Research or institutional support from a publisher; 7=Research or institutional support from a company or supplier; 8=Stock or Stock Options; 9=Other financial/material support from a publisher; 10=Other financial/material support from a company or supplier).

• The FDA has not cleared this drug and/or medical device for the use described in this presentation   (i.e., the drug or medical device is being discussed for an “off label” use).  ◆FDA information not available at time of printing. Δ OTA Grant