Magnetic resonance imaging for clearing the cervical spine in unconscious intensive care trauma patients.

Injuries to the cervical spine occur in 2.0 to 6.6% of blunt trauma patients, with the co-existence of head injury increasing the incidence of cervical spine injury to 10%. Injury to the cervical spinal cord in the absence of fracture occurs in 0.07 to 0.7% of trauma admissions. Missed or delayed diagnosis of cervical spine injury occurs in 4 to 8% of patients, whereas for the whole spine, missed or delayed diagnosis results in 10 times the incidence of secondary neurologic deficit compared with patients who have correct diagnosis initially. Of the patients with missed or delayed diagnosis of cervical spine injury, 70% have altered levels of consciousness. The potential physical, social, and economic issues associated with missing or delaying diagnosis are far-reaching, with the lifetime healthcare and living costs for a quadriplegic patient estimated to be in the vicinity of $1.2 to 2.2 million USD ($2.4 to 3.1 million AUD). Immobilization of the entire spine is required until clearance, which has occurred when clinicians have examined the patient physically and radiologically and have excluded injury. Although magnetic resonance imaging (MRI) has an established role for the investigation of suspected spinal cord injuries, the role of MRI in cervical spine clearance protocols for obtunded or comatose trauma patients is debated. MRI is superior to other radiologic techniques for the diagnosis of spinal cord injury, but whether MRI-diagnosed discoligamentous injuries influence clinical management is unknown. Many trauma centers advocate the use of traditional protocols for spinal clearance, such as those devised by the Eastern Association for the Surgery of Trauma (EAST). Under these protocols, trauma patients undergo a three-view cervical plain radiograph series (anteroposterior, lateral, and odontoid views) plus axial computed tomography (CT) in areas of the spine in which visualization is poor or where suspicion of injury exists. Due to position restrictions and the presence of essential clinical equipment, however, adequate plain films are often difficult to achieve in unconscious trauma patients. CT, although superior to MRI in the diagnosis of fractures, may be inadequate in the detection of soft-tissue injury in the absence of fracture or malalignment. The relatively recent introduction of multislice or multidetector CT, however, has resulted in significant decrease in artifact and enhancement of the clarity of reformatted images, to the extent that detection of some soft-tissue injury is now possible. Subsequently, some centers have opted to use cervical spine multislice CT as the initial screening tool in preference to plain radiography. There have been no randomized controlled studies undertaken to assess the efficiency of specific cervical radiographic imaging strategies with regard to injury detection. Ethical issues arise when considering which patients will undergo particular cervical imaging procedures and in determining the level of risk of cervical injury. Observational studies, therefore, provide the most appropriate option for the evaluation of cervical spine imaging protocols. There have been several relevant studies examining the radiographic detection of cervical soft-tissue injury in blunt trauma patients generally, many of which explore the specific issues inherent in the evaluation of unconscious intensive care patients. The quality of the studies summarized in this review is outlined in Table 1, and the classification is based on that utilized by the EAST guidelines. Studies of superior quality enrolled greater than 100 patients, were prospective in nature, and defined the study population at risk, the specialties of the consultants who reported on the images, and the radiographic images obtained in the study. The conclusions reached by the respective authors are summarized in Table 1. The safety of spinal clearance and cessation of spinal position restrictions in unconscious trauma patients without definitive knowledge of the discoligamentous status is debated. Several studies have been undertaken to assess spinal clearance under these circumstances. Ghanta et al. performed a retrospective study of 124 trauma patients, including 59 unconscious patients, who had undergone three-view cervical plain radiographs and full CT. MRI of the cervical spine was performed when there was suspicion of cervical Submitted for publication October 15, 2004. Accepted for publication May 20, 2005. Copyright © 2006 by Lippincott Williams & Wilkins, Inc. From the National Trauma Research Institute (H.M.A., D.J.C.), Melbourne; the Intensive Care Department (D.J.C.) and the Neurosurgery Department (G.M.M.), The Alfred Hospital, Melbourne; Departments of Medicine, Surgery and Epidemiology and Preventive Medicine (D.J.C.) Monash University, Melbourne; and the Department of Radiology (S.L.S.), Princess Alexandra Hospital, Brisbane, Australia. Address for reprints: Helen Ackland, Trauma Research Fellow, National Trauma Research Institute, The Alfred Hospital, P.O. Box 315, Prahran, Victoria, Australia, 3181; email: [email protected].