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Three Part Question

In [obtunded adult patients with blunt trauma] will [CT scan of cervical spine] exclude [all unstable ligamentous injuries]

Clinical Scenario

A 30 yr old man who has been involved in a car crash has been brought to your ED. His GCS is 7 and he was intubated in ED and underwent trauma series CT. His CT cervical spine has been reported as normal. He is about to be transferred to ICU and you are wondering whether CT cervical spine alone can exclude unstable ligamentous injury?

Search Strategy

MEDLINE & EMBASE were searched from 1980 till 2011 using the health information services interface
MEDLINE search ( 1.{exp TOMOGRAPHY, X-RAY COMPUTED} 2.{"CT scan" ti,ab} 3.{1 OR 2} 4.{exp MAGNETIC RESONANCE IMAGING} 5.{"MRI" ti,ab} 6.{4 OR 5} 7.{3 AND 6} 8.{exp SPINAL INJURIES OR exp DISLOCATIONS OR exp SPINAL CORD INJURIES} 9.{"cervical spine" ti,ab} 10.{8 OR 9} 11.{7 AND 10} 12.{trauma OR clearance OR obtunded OR comatose OR injur*} ti,ab 13.{11 AND 12} )

EMBASE search 1. {exp COMPUTER ASSISTED TOMOGRAPHY} 2. {"CT" OR "CT scan"}ti,ab 3. {1 OR 2} 4. {exp NUCLEAR MAGNETIC RESONANCE IMAGING} 5. {"MRI" OR "MR scan"}ti,ab 6. {4 OR 5} 7. {3 AND 6} 8. {exp CERVICAL SPINE} 9. {7 AND 8} 10. {trauma OR clearance OR obtunded OR comatose OR injur*}ti,ab 11. {9 AND 10}

Search Outcome

MEDLINE search showed 416 papers out of which 10 was relevant. EMBASE search 140 papers out of which 1 was relevant.

Only studies which looked at obtunded pts with normal CT cervical spine who went onto have MRI scan were included. The papers were limited to English language and humans.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Menaker J et al 2010 USA	This study was to determine if 40 slice CT scan can rule out cervical spine injury	Retrospective	96 obtunded pts with normal CT scan	15 (15%) pts had abnormalities detected by MRI. One needed operative repair	No details given on what type of ligament injury was there and on the eventual discharge outcome
Schoenwaelder M et al 2009 Australia	The purpose of this study was to determine the role of MRI in intubated multi trauma pts with normal CT cervical spine in order to exclude unstable injury	Retrospective	55 pts with normal CT scan	10 (18%) pts were MRI positive for injury. None were unstable or required operative repair	An MRI fellowship trained radiologist has reported the MRI scan and this may have resulted in more abnormalities being picked up.
			Occurrence of DVT with clivarin prophylaxis	9 patients (6.3%)
			Occurrence of DVT with aspirin prophylaxis	7 patients (4.8%)
Tomycz ND et al 2008 USA	This study looked to see if MRI was necessary to clear the cervical spine in the obtunded trauma pt	Retrospective	180 pts with normal CT scan underwent MRI scan	38 (21%) pts had injuries detected by MRI. Two pts had two column injury. None needed operative repairt	No long term follow up of pts
Steigelman M et al 2008 USA	This study looked to see if MRI was needed after a normal CT scan	Retrospective	120 obtunded pts with normal CT scan	7 (5%) pts had abnormalities detected by MRI. None were unstable or needed operative repair	MRI was done mostly beyond 7 days. No details as to who reported the scans were given.
Menaker J et al 2008 USA	This study looked to see if MRI would bring a change in management as they hypothesised that CT scan alone misses cervical spine injuries	Retrospective	Out of 203 pts, 184 had a negative MRI. One had suboptimal MR finding and 18 had abnormalities detected	18 pts had abnormalities detected by MRI. Two needed operative repair.	No blinding of the staff to the CT scan results
Sarani B et al 2007 USA	This study was to ascertain the incidence of cervical spine injury detected by MRI in CT cervical spine normal pt and also to see if treatment plan was altered on the basis of the finding	Retrospective	53 obtunded pts of whom 46 had normal CT	MRI detected undiscovered injuries in 5 (10%) pts. None were unstable or required operative repair	Small sample size
Como JJ et al 2007 USA	This study looke to see if MRI was needed in obtunded blunt trauma pts if CT cervical spine was normal	Prospective	115 pts of whom MRI identified acute injuries in 6 (5%) pts	No pt with unstable injury or needing operative repair was missed	MRI was done on average 7.5 days after injury
Adams JM et al 2006 USA	Comparing the sensitivity of CT to MRI for detection of spinal injury	Retrospective	Out of 97 pts in the study, 29 were obtunded	Of 29 obtunded pts 20 were CT negative and of these the MRI did not detect any new cervical spine injury	No details has been given as to whether all obtunded pts with normal CT went onto have an MRI or not.
Stassen NA et al 2006 USA	To evaluate the safety & efficacy of the new hospital guideline on clearing cervical spine using CT & MRI	Retrospective	13 pts had injuries detected by MRI	None needed operative repair	No details on what the ligament injuries were
Hogan GJ et al 2005 USA	To determine what new information MRI is able to deliver in pts with a negative CT cervical spine	Retrospective	366 pts of whom 354 were MRI negative for acute injury	CT had a negative predictive value of 98% for ligament injury & 100% for unstable injury	MRI was performed on average at day 9 only
Kihiczak D et al 2001 USA	the study looked at the type of injuries picked up on MRI cervical spine after a negative CT scan	retrospective	59 pts with CT negative of whom 19 were obtunded	Out of the 19 pts there were 2 pts with positive MRI findings. None needed operative repair or were unstable	Small sample size. No long term follow up of pts.

Comment(s)

From the eleven papers, a total of 1264 obtunded patients underwent MRI after normal CT cervical spine. All the studies are from level 1 trauma centres. Most of the MRI scans were done after day 4. MRI detected injuries in 126 patients. Three required operative repair and two had two column ligament injury. The negative predictive value of CT to detect unstable injury or injuries requiring operative repair is 99.6%. The 95% confidence interval is 99.25 to 99.95, the negative predictive value of CT for any ligament injury is 90%, the 95% confidence interval is 88.38 to 91.68.

Prolonged cervical spine immobilisation is not without its own complications, but the aim of this review was not to primarily look into that. The chance of missing an unstable injury by CT alone is 0.4% (which means approximately 4 out of 1000 pts would have an unstable injury) and 9.9% for any ligamentous injury. We still don't know the long term significance of these injuries and indeed if an unstable ligament would result in neurological sequelae. There are significant variations in practice between institutions

Editor Comment

ED - emergency department

Clinical Bottom Line

Based on the above studies CT alone would miss ligamentous injuries.Institutions need to balance this potential risk against the risks of continued cervical spine immobilisation(raised intracranial pressure, pneumonia, pressure areas) or universal MRI in such cases

Level of Evidence

Level 2 - Studies considered were neither 1 or 3.

References

1. Menaker J et al 40-slice multidetector CT: is MRI still necessary for cervical spine clearance after blunt trauma? Am Surg 2010 Feb; 76(2):157-63
2. Schoenwaelder M et al Assessing potential spinal injury in the intubated multitrauma patient: does MRI add value? Emergency Radiology 2009; 16:129-132
3. Tomycz ND et al MRI is unnecessary to clear the cervical spine in obtunded/comatose trauma patients: the four year experience of a level 1 trauma centre Journal of Trauma 2008; 64(5): 1258-63
4. Steigelman M et al Screening cervical spine MRI after normal cervical spine CT scans in patients in whom cervical spine injury cannot be excluded by physical examination American Journal of Surgery 2008; 196:857-863
5. Menaker J et al Computerised tomography alone for cervical spine clearance in the unreliable patient – are we there yet? Journal of Trauma 2008;64(4):898-904
6. Sarani B et al Magnetic resonance imaging is a useful adjunct in the evaluation of the cervical spine of injured patient Journal of Trauma 2007;63:637-640
7. Como JJ et al Is magnetic resonance imaging essential in clearing the cervical spine in obtunded patients with blunt trauma Journal of Trauma 2007;63:544-549
8. Adams JM et al Spinal clearance in the difficult trauma patient: A role for screening MRI of the spine. The American Surgeon 2006;72:101-5
9. Stassen NA 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 Journal of Trauma 2006;60:171-177
10. Hogan GJ et al Exclusion of unstable cervical spine injury in obtunded patients with blunt trauma: is MR imaging Radiology 2005;237(1):106-13
11. Kihiczak D et al Should an MR scan be performed routinely after a normal clearance CT scan in the trauma patient? Experience with 59 cases. Emergency Radiology 2001;8:276-278