Tag Archives: AAST 2016

Imaging

Cervical Spine MRI After Negative CT

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dislocation-atlanto-axial-0005

There are multiple ways to clear a cervical spine! Most centers use a combination of clinical decision tools and CT scan in adults. The gold standard tie breaker, warranted or not, seems to be MRI. This tool is only used in select cases where conventional imaging is in doubt, or the clinical exam is puzzling.

Some centers clear based on CT only as long as imaging is indicated. Some use MRI in cases where patients continue to complain of midline neck pain or tenderness after negative CT. A multi-center trial encompassing 8 Level I and II centers prospectively performed MRI on patients who could not be clinically evaluated, or had persistent midline cervical pain after normal CT.

A total of 767 patients were seen over a 30 month period. Besides looking at the usual data points, the authors were interested in new diagnoses and changes in management based on the MRI results.

Here are the factoids:

  • Neck pain and inability to evaluate occurred with equal frequency, about 45%; the remaining 10% had both
  • 23% of MRIs were abnormal, with 17% ligament injury, 4% swelling, 1% disk injury, and 1% dural hematomas.
  • Patients with normal and abnormal MRI had neurologic anomalies about equally (15-19%). [Why are these patients included? Were they initially not evaluable?]
  • The cervical collar was removed in 88% of patients with normal MRI (??), and in 13% with abnormal MRI
  • After (presumably) positive MRI, 14 (2%) underwent spine surgery; 8 of these had neurologic signs or symptoms

Bottom line: I’m a bit confused. If the authors were really trying to figure out the rate of abnormal MRI after negative CT, they should have excluded the patients with known neurologic findings. These patients should nearly always have an abnormal MRI. And why did they not take the collar off of the 12% of patients with both normal CT and MRI??

Hopefully, details in the presentation next week will help explain all this. I suspect that the study will show that there are cases where CT is normal but MRI is not. The abstract does not clearly describe how many of these are clinically significant.

I admit, I’m not very comfortable clearing the cervical spine in a patient with negative CT (even if read by a neuroradiologist) and obvious midline neck pain/tenderness. I hope this study helps clarify this issue. We shall see…

Reference: Cervical spine MRI in patients with negative CT: a prospective, multicenter study of the research consortium of New England centers for trauma (ReCONECT). AAST 2016, Paper 61.

Pelvis

Early Operative Fixation of Pelvic Fractures And Functional Outcome

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Disruption of the pelvic bones takes a huge amount of energy, and results in significant bleeding and morbidity from other causes. Repair typically consists of surgical fixation, frequently with temporary external fixation in the interim. These patients require intensive therapy postoperatively, with inpatient rehab prior to discharge home.

How well do patients with severe pelvic fractures do in the longer term? The group at the University of Tennessee in Memphis did a lengthy followup study spanning 18 years of severe pelvic fractures treated at their hospital. These patients had sustained fractures with significant bleeding, an open book component, or SI joint disruption with vertical shear.

open book pelvis pre

The authors used phone interviews and a standardized measurement instrument (Activity Measure for Post-Acute Care, AM-PAC) to gauge daily activity of affected patients. They then looked for factors predictive of functional outcome.

Here are the factoids:

  • 401 patients were identified over the 18 year study period
  • Of these only 71% survived (285), and the study documented followup in 145 (51%)
  • Average ISS was 27 (fairly high) and patients tended to be older (mean 53 years)
  • Even after 8 to 20 years, mobility and activity were significantly impaired as measured by AM-PAC
  • Time to fixation was the only identifiable factor that had an impact on decreased mobility or activity

Bottom line: Early definitive fixation of the pelvis was the only variable found that had an impact on future mobility and activity. Frequently, external fixation is applied soon after admission. But remember, your trauma patient is at their healthiest as they roll through the doors of your ED. The sooner they get all of their problems fixed, the better (and safer).

Impact of early operative pelvic fixation on long-term functional outcome following sever pelvic fracture. AAST 2016, Paper 60.

Abdomen

Spleen Injury, Angiography, And Splenectomy

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The shift toward initial nonoperative management of spleen injuries began in the early 1990’s, as the resolution of early CT scans began to improve. Our understanding of the indicators of failure also improved over time, and success rates rose and splenectomy rates fell.

Angiography was adopted as an adjunct to early management, especially when we figured out what contrast extravasation and pseudoaneurysms really meant (bad news, and nearly certain failure in adults). At first, it was used in a shotgun approach in most of the higher grade injuries. But we have refined it over the years, and now it is used far more selectively at most centers.

A group at Indiana University was interested in looking at the impact of angio use on splenic salvage over a long time frame. They queried the National Trauma Data Bank, looking specifically at high grade splenic injury care at Level I and II centers from 2008-2014. Patients undergoing splenectomy were divided into early (<= 6hr after admission) and late (> 6 hrs). Over 50,000 records were analyzed.

Here are the factoids:

  • There was a shift from early splenectomy to late splenectomy over the study period that was statistically significant
  • Use of angio increased from 5 to 12% during the study period
  • Overall splenectomy rate remained about the same

So the authors recognize that late splenectomy has decreased. But they also state that early splenectomy has increased. They attribute it to increased recognition of patient requiring early splenectomy. They then call into question the need to use angiography if it hasn’t decreased the overall splenectomy rate.

Problem: The early splenectomy rate increased from about 13% to 14%, reading their graph, and is probably not significant. These are the failures that occur in the trauma bay and shortly thereafter that must be taken to the OR. The late splenectomy rate decreased from 5% to 3%, which may be significant (p value not included in the abstract). These are failures during nonoperative management, and are decreasing over time. And BTW, the authors do not define what “high grade” splenic injuries they are looking at.

AAST2016-Paper35

Bottom line: This abstract illustrates why it is important to read the entire article, or in this case, listen to the full presentation at AAST. It sounds like one that’s been written to justify not having angiography available as it is currently required. 

The authors showed that overall splenectomy rate was the same, but delayed splenectomy (late failure) has decreased with increasing use of angiography. But remember, this is an association, not cause and effect. Most of the early failures are still probably ones that can’t be prevented, but we’ll see if the authors can dissect out how many went to OR very early (not eligible for angio), or later in the 6 hour period (could have used angio). It looks to me like the use of angiography is having the desired effect. But undoubtedly we could use that resource more wisely. What we really need are some guidelines as to exactly when a call to the interventional radiologists is warranted.

Related posts:

Reference: Overall splenectomy rates remain the same despite increasing usage of angiography in the management of high grade blunt splenic injury. AAST 2016, paper 35.