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

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.