Comparison of CT and MRI findings for cervical spine clearance in obtunded patients without high impact trauma

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Abstract

Objective

Cervical spinal injuries occur in 2.0–6.6% of patients after blunt trauma and can have devastating neurological sequelae if left unrecognized. Although there is high quality evidence addressing cervical clearance in asymptomatic and symptomatic awake patients, cervical spine clearance in patients with altered level of alertness (i.e., obtunded patients with Glasgow coma scale (GCS) of 14 or less) following blunt trauma has been a matter of great controversy. Furthermore, there are no data on cervical spine clearance in obtunded patients without high impact trauma and these patients are often treated based on evidence from similar patients with high impact trauma. This retrospective study was conducted on this specific subgroup of patients who were admitted to a neurointensive care unit (NICU) with primary diagnoses of intracranial hemorrhage with history of minor trauma; the objective being to evaluate and compare cervical spinal computed tomography (CT) and magnetic resonance imaging (MRI) findings in this particular group of patients.

Methods

Patients with GCS of 14 or less admitted to neruointensive care unit (NICU) at RUSH University Medical Center from 2008 to 2010 with diagnoses of intracranial hemorrhage (surgical or non-surgical) who had reported or presumed fall (i.e., “found down”) were queried from the computer data registry. A group of these patients had cervical spine CT and subsequently MRI for clearing the cervical spine and removal of the cervical collar. Medical records of these patients were reviewed for demographics, GCS score and injury specific data and presence or absence of cervical spine injury.

Results

Eighty-three patients were identified from the computer database. Twenty-eight of these patients had positive findings on both CT and MRI (33.73% – Group I); four patients had a negative CT but had positive findings on follow-up MRI (4.82% – Group II); fifty-one patients had both negative CT and MRI (61.44% – Group III). All patients in Group I required either surgical stabilization or continuation of rigid cervical orthosis. All four patients in Group II had intramedullary T2 hyper intensity consistent with possible spinal cord injury on MRI, but did not have any signs of fracture or ligamentous injury to suggest instability. They eventually underwent surgical decompression of the spinal cord during the same hospital stay. Cervical collars were safely removed in all patients in Group III. In our retrospective study, CT had a sensitivity of 0.875 [0.719–0.950, 95% CI] and a specificity of 1.000 [0.930–1.000, 95% CI] in detecting all cervical spine injuries compared to MRI. However, all patients with missed injuries had intramedullary T2 hyper intensity consistent with possible spinal cord injury on MRI and were not unstable precluding cervical spine clearance. If only unstable injuries are considered, CT had a sensitivity of 1.00 [0.879–1.000, 95% CI] and a specificity is 1.000 [0.935–1.000, 95% CI] compared to MRI in this particular group of patients.

Conclusion

CT is highly sensitive in detecting unstable injuries in obtunded patients with GCS of 14 or less in the absence of high impact trauma. In the absence of high impact trauma, neurosurgeons should be comfortable to discontinue the cervical collar after a negative, high-quality CT in this patient population. In the presence of focal neurological deficits unexplained by associated intracranial injury, an MRI may help diagnose intrinsic spinal cord injuries which necessarily may not be unstable in the presence of a negative CT and does not precludes clearance of cervical spine.

Introduction

Cervical spine assessment and clearance is a priority in patients with suspected with cervical spine trauma due to potential devastating neurological deficits that can result from cervical spine injuries. There are well-established guidelines for cervical clearance in patients who are fully awake (Glasgow coma scale [GCS] = 15) with a reliable neurological exam, as described in the National Emergency X-Radiography Utilization Study (NEXUS) criteria and Canadian C-Spine (cervical-spine) Rule (CCR) [1]. Cervical spine clearance can however be challenging in obtunded patients with GCS of 14 or less and is a matter of great conjecture. Obtunded patients with suspected cervical spine injury are usually kept in rigid collars for cervical immobilization. Prolonged use of rigid collar is not only associated with increased incidence of pressure ulcers and intracranial pressure (ICP) elevation [2], [3], [4], but also presents challenges for oral hygiene, airway management and daily nursing care. Thus, safe and timely removal of cervical collars in obtunded patients has important clinical implications. With increased availability of high-resolution multi-detector computed tomography (MDCT), there have been reports of using MDCT alone for clearance of cervical spine in patients with blunt trauma who have non-focal examinations. The advantages of it being wider availability of CT, quick scan time and high sensitivity in detecting bony abnormalities such as acute fractures. However, many studies have shown that CT alone can miss clinically significant soft tissue injuries [5], [6], [7], [8], [9], [10], [11], [12], especially in patients with high impact trauma. Magnetic resonance imaging (MRI) is highly sensitive in detecting soft tissue and ligamentous injuries but is much more time intensive and is not as readily available compared to CT. Even with technological advances with dramatic improvement in quality and resolution of CT, there is contradictory evidence in the value of CT alone for cervical spine clearance in obtunded patients [5], [7], [8], [9], [12], [13], [14], [15], [16], [17], [18], [19], [20]. Hence various studies have evaluated the role of CT alone or in conjunction with single upright radiographs or MRI to clear cervical spine injury in obtunded patients. While negative CT and MRI in obtunded patients have a very high degree of specificity in clearing the cervical spine, the value of a positive MRI is poorly understood and can be redundant leading to retaining the collar for longer periods due to lack of well defined criteria for instability on MRI with its very high sensitivity for detecting soft tissue trauma not necessarily ligamentous with undetermined clinical significance [16]. There is no universally accepted protocol regarding the cervical spine clearance in obtunded patients without history high impact trauma and the data on whether a negative CT alone is enough to clear cervical spine in this subgroup of patients is lacking. This clinical scenario is commonly encountered in many neruointensive care units (NICUs), where patients are admitted with being obtunded following some intracranial pathology and either have a fall secondary to that or are reported as “found down” with not even a witnessed history of trauma. These patients arrive in cervical collar to the NICU where neurosurgeons are often consulted for cervical spine clearance by the neurologists and neurointensivists. Given many of these patients have altered level of alertness with concurrent intracranial pathologies (subarachnoid hemorrhage [SAH], intracerebral hemorrhage [ICH], subdural hemorrhage [SDH]), they often do not cooperative fully for adequate and accurate assessment of strength or sensation or are not even conscious secondarily to the intracranial injury. While the absence of significance trauma makes the probability of cervical spine injury unlikely, theoretically increasing the negative predictive value of a negative CT scan, their intracranial pathologies often produce neurological deficits that cannot be clearly distinguished from possible cervical spine injury. Given above reasons, many of these patients ended up getting MRI for the purpose of cervical spine clearance.

At our institution, we receive a significant number of patients from other institutions with the diagnosis of intracranial hemorrhage (primarily SAH, ICH, and SDH). Many of these patients arrive with cervical collars due to history of “fall” or “found down” with no history of high impact trauma and have unreliable neurological exams. It is the routine practice of the neurointensivists at our institution to image the cervical spines of such individuals which often involves CT and MRI. We initiated this study to focus on this subgroup of patients to evaluate and compare the cervical CT and MRI findings.

Section snippets

Methods

Electronic medical record database at RUSH University Medical Center, Chicago, IL was queried for patients admitted to the NICU with the diagnosis of intracranial hemorrhage and concomitant history of minor cervical spine trauma most commonly ground level fall between January 2008 and December 2010. The study group primarily consisted of patients with SAH, ICH or SDH with history of “ground level fall” or “found down” and have unreliable neurological exams. Those who underwent both CT (Siemens,

Results

Eighty-three patients were identified from the computer database using our search criteria. Twenty-eight (33.73%) patients had pathologies identified on both CT and MRI (Group I); four patients (4.82%) had a negative CT but had positive finding on MRI (Group II); fifty-one patients (61.44%) had both negative CT and MRI (Group III). Results are summarized in Table 1.

All patients in Group I required either surgical stabilization or continuation of rigid cervical orthosis. All four patients in

Discussion

NEXUS and Eastern Association of the Surgery of Trauma (EAST) guidelines have been well-established and are standards for cervical spine clearance in patients who are awake, alert and cooperative with neurological exam. The NEXUS criteria have a sensitivity of 99.9% in detecting significant cervical injuries [1]. However, cervical spine clearance in obtunded patients (GCS of 14 or less) has been a persistent topic of debate. No universally accepted guidelines exist for this group of patients.

Conclusion

CT is a very useful imaging modality in evaluation cervical spine in obtunded patients with unreliable neurological exams. A negative high-quality CT scan is very reassuring and in the absence of high impact trauma as is seen in this patient population seems adequate for cervical spine clearance. Performance of routine MRI in this subgroup of patients without history of high impact trauma seems redundant following a negative high quality CT scan and may be avoided for the purpose of cervical

Funding

None.

References (27)

  • G. Davies et al.

    The effect of a rigid collar on intracranial pressure

    Injury

    (1996)
  • J.C. Kolb et al.

    Cervical collar-induced changes in intracranial pressure

    Am J Emerg Med

    (1999)
  • J.R. Hoffman et al.

    Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group

    N Engl J Med

    (2000)
  • R.J. Mobbs et al.

    Effect of cervical hard collar on intracranial pressure after head injury

    ANZ J Surg

    (2002)
  • K. Hunt et al.

    The effects of rigid collar placement on intracranial and cerebral perfusion pressures

    Anaesthesia

    (2001)
  • C.V. Brown et al.

    Computed tomography versus magnetic resonance imaging for evaluation of the cervical spine: how many slices do you need?

    Am Surg

    (2010)
  • C.M. Dunham et al.

    Risks associated with magnetic resonance imaging and cervical collar in comatose, blunt trauma patients with negative comprehensive cervical spine computed tomography and no apparent spinal deficit

    Crit Care

    (2008)
  • J. Menaker et al.

    Computed tomography alone for cervical spine clearance in the unreliable patient – are we there yet?

    J Trauma

    (2008)
  • J. Menaker et al.

    40-slice multidetector CT: is MRI still necessary for cervical spine clearance after blunt trauma?

    Am Surg

    (2010)
  • R.D. Muchow et al.

    Magnetic resonance imaging (MRI) in the clearance of the cervical spine in blunt trauma: a meta-analysis

    J Trauma

    (2008)
  • G.J. Hogan et al.

    Exclusion of unstable cervical spine injury in obtunded patients with blunt trauma: is MR imaging needed when multi-detector row CT findings are normal?

    Radiology

    (2005)
  • V. Spiteri et al.

    Cervical dynamic screening in spinal clearance: now redundant

    J Trauma

    (2006)
  • N.A. Stassen et al.

    Magnetic resonance imaging in combination with helical computed tomography provides a safe and efficient method of cervical spine clearance in the obtunded trauma patient

    J Trauma

    (2006)
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