Update on the appropriate radiographic studies for cervical spine: evaluation and clearance in the polytraumatized patient

The role of magnetic resonance imaging in acute cervical spine fractures

BACKGROUND CONTEXT

The role of magnetic resonance imaging (MRI) in neurologically intact cervical spine fractures is not well defined. To our knowledge, there are no studies that clearly identify the indications for MRI in this particular scenario. Controversy remains regarding the use of MRI in at-risk patients, primarily the obtunded and elderly patients.

PURPOSE

The purpose of the present study was to examine the predisposing conditions where an MRI would provide additional findings that would affect management in acute cervical spine fractures.

STUDY DESIGN

Retrospective cohort involving radiographic and clinical review.

PATIENT SAMPLE

Consecutive patients with acute cervical injuries at a single institution.

OUTCOME MEASURES

Neurologic recovery.

METHODS

A review of 830 patients with cervical spinal injuries between 2006 and 2010 was performed. Clinical information was obtained for all the patients: Glasgow Coma Scale, mechanism of injury, major medical comorbidities, associated injuries, neurologic examination, neurologic symptoms, sex, age, and alertness. Two experienced fellowship-trained spine surgeons determined if the MRI study changed the management in the individual cases based on the Sub-axial Cervical Spine Injury classification system.

RESULTS

Ninety-nine patients with a cervical fracture were included in the final analysis: median age 54 years (interquartile range, 42 years), mean Glasgow Coma Scale 13 (standard deviation ± 3.0), 68% males, 32% females, 42% older patients (age>60 years), 30% spondylosis, 27% polytrauma, 67% alert, 28% neurologic deficit. Major medical comorbidities, prior to injury level of activity, atlantoaxial versus subaxial, and gender were not associated with changes in diagnosis and management (p>.05). Age >60 years, neurologic deficit, polytrauma status, alertness, and spondylosis were associated with having additional clinically relevant findings seen on MRI and changes in management (p<.05). The majority of the changes in management were related to MRI's illustration of the spinal cord injury and not due to an occult instability. Eighty-one percent of the changes in management were related to the depiction of the spinal cord compression seen on MRI, whereas 19% of the changes in management were related to occult instability seen on MRI.

CONCLUSIONS

Older age (>60 years), obtunded or temporary non-assessable status, cervical spondylosis, polytrauma, and neurologic deficit are predisposing factors for further injury found on MRI but missed on computed tomographic scan alone. These additional findings can affect the management in acute cervical spine fractures. The rational of the on-call spine surgeon to order an MRI for a cervical spine fracture is well founded and often that MRI will affect the fracture management. Magnetic resonance imaging particularly helps with better defining the type of spinal cord compression. Picking up occult instability missed on computed tomographic scan was possible with MRI but not as common.

The daunting task of "clearing" the cervical spine

The evaluation of the cervical spine in the emergency department is a common and often challenging task. We report the case of a 70-year-old female who presented intoxicated with evidence of a recent fall. A 64-slice computed tomographic (CT) scan with sagittal and coronal reconstructions revealed no acute injury. The patient was re-examined when alert and had persistent neck pain. Flexion-extension static views revealed severe subluxation of C5 on C6 with jumped facets, and subsequent magnetic resonance imaging confirmed significant ligamentous injury. The evidence available suggests that although CT with reconstruction is highly sensitive for clinically significant cervical injury, the possibility of severe injury remains.

Clearing the cervical spine in the blunt trauma patient

The goal of cervical spine clearance is to establish that injuries are not present. Patients are classified into four groups: asymptomatic, temporarily nonassessable secondary to distracting injuries or intoxication, symptomatic, and obtunded. Level I evidence supports that the asymptomatic patient can be cleared on clinical grounds and does not require imaging. The temporarily nonassessable patient may have short-term mental status changes (eg, intoxication, painful distracting injuries) and can be evaluated by two methods. When there is urgency, the evaluation is similar to that for the obtunded patient. Alternatively, the patient can be reevaluated within 24 to 48 hours, after return of mentation or following treatment of painful injuries. The patient then can be assessed as the asymptomatic patient is. The symptomatic patient requires advanced imaging. The obtunded patient should undergo, at minimum, a multidetector CT scan. Two methods are advocated. One uses only multidetector CT; a normal result is sufficient to clear the obtunded patient. The alternative method is obtaining a magnetic resonance image subsequent to a negative multidetector CT scan. Because at present information is insufficient to determine whether MRI is indicated, this is an area of controversy.