Evaluation of the Thoracic and Lumbar Spine in Blunt Trauma

Journal Club Podcast #48: February 2019

Thoracic Lumbar Spine.jpg

A look at the utility of history, physical exam, and plain radiography for detecting clinically significant injuries of the thoracic and lumbar spine…

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Articles:
Vignette:

You're working a shift at a level II trauma center in the community one rainy afternoon when EMS brings in Mr. Q, a 62-year-old man with hypertension and hyperlipidemia who was involved in a motor vehicle collision. He was the unrestrained driver in a car that hydroplaned on the highway and collided with the concrete barrier. His car spun around and was struck on the driver's side before coming to rest in the median. The driver had LOC and ended up in the passenger side of the car. His only complaint is a headache and chest pain. He arrives awake, alert, with abrasions and contusions to his upper face. He has no midline cervical, thoracic, or lumbar spine tenderness and he is neurologically intact.

Your next patient is Ms. P, a 47-year-old female with no significant past history who slipped on the wet stairs outside her apartment building. She ended up falling down four stairs, landing primarily on her buttocks. She complains of coccygeal and left hip pain, but denies back or neck pain. She has no midline tenderness in her cervical or thoracic spine, but does have tenderness in the midline lumbar spine, around L2/3. She is neurologically intact.

You consider your imaging options in both of these patients. For the first patient, you are planning to get a CT of his head, face, and cervical spine, and are considering a CT of the chest, abdomen, and pelvis as well, based purely on the mechanism of injury. You wonder if you even need to consider imaging of the thoracic and lumbar spine, given his lack of physical exam findings, and if so, wonder if you should get CT reconstructions or if plain films would suffice. In the second case, in addition to imaging of the pelvis and left hip, you are planning to get plain films of the lumbar spine. Again, you wonder if this is sufficient, or if you need to get more advanced imaging (such as a CT) to evaluate for fracture.

The first patient gets a "pan-scan" and is found to have isolated facial bone fractures, for which he is evaluated by ENT and eventually discharged home. The second patient is found to have no fractures on plain films, feels much better after ibuprofen, and also goes home. You still have questions about your imaging choices, and a quick look online directs you to a recent systematic review on the evaluation of thoracic and lumbar spine following blunt trauma. Wondering what other literature there is, you begin to conduct a more thorough search...

PICO Question:

Population: Adult patients suffering blunt trauma

Intervention: Aspects of history (e.g. mechanism of injury) and physical exam, plain radiography

Comparison: CT scan, surgical findings, follow-up

Outcome: Need for surgical intervention or TLSO bracing

Search Strategy:

A systematic review and meta-analysis, recently published by a collaboration of physicians that included one Washington University emergency physician and recent graduate of our residency program, was first identified. The bibliography of this review was searched to identify three additional relevant studies.

Bottom Line:

Evaluation for injury of the cervical spine following blunt trauma was made much easier by the derivation and subsequent validation of key clinical decision rules (NEXUS criteria, Canadian c-spine rule). Unfortunately, no such rule exists for evaluation of the thoracic and lumbar spine. At least one observational study from LA County/USC Medical Center (Inaba 2011) suggested that physical exam alone performed poorly at evaluating for a “clinically significant” injury of the thoracic or lumbar spine, with with a sensitivity of 78.6%, specificity of 83.4%, LR+ of 4.73, and LR- of 0.26. A recent systematic review on this topic (VandenBerg 2018) similarly found that aspects of the history and physical exam (when looked at independently) were inadequate at ruling in or out disease. Mechanism of injury had a pooled LR+ ranging from 0.5 to 1.7 and LR- of 0.63 to 1.25. There was no negative finding on physical examination that significantly reduced the probability of finding a TL-spine fracture, although the presence of a palpable spine deformity was good at ruling in a fracture, with a LR+ of 15.3.

Various imaging modalities have also been evaluated, with some studies suggesting that plain films alone are inadequate to detect injury. One study looking at trauma to the thoracic spine (Karul 2013) found that plain radiography had a LR+ of 1.09 and LR- of 0.93, suggesting that such films are useless whether they are positive or negative for fracture. Unfortunately, this study was severely limited by incorporation bias (CT was the ultimate gold standard) and spectrum bias, as the study only included patients with a thoracic spine deformity or step-off on exam who were still having pain within 10 days. This study did not address the utility of plain films in patients at lower risk of injury.

The systematic review by VandenBerg et al identified additional studies looking at the diagnostic accuracy of various imaging modalities. Five studies evaluated the accuracy of plain films of T and L-spine, with a pooled LR+ of 25.0 (95% CI 4.1-152.2) and LR- of 0.43 (95% CI 0.32-0.59) for diagnosis of injury. Similar likelihood ratios were found when pooling studies looking only at the thoracic spine or only at the lumbar spine. Studies evaluating CT of the chest, abdomen, and pelvis and those looking at reformatted thoracic and lumbar CT found a high degree of accuracy with either modality. As noted by the authors of the review, this evidence is based primarily on retrospective studies at high risk of incorporation bias. Additionally, many of these studies used as their outcome a “significant injury,” which included both the need for surgery or the need for TLSO bracing. Recent research suggests that TLSO bracing (primarily used for burst fractures) is not beneficial (Bailey 2014), and this outcome may not be as patient-centered as intended.

One clinical decision rule has been derived (Inaba 2015), with resulting sensitivity and specificity of 98.9% and 29.0%, respectively. This corresponds to a negative likelihood ratio of 0.04, suggesting the rule could significantly reduce the risk of a clinically significant fracture when negative. Unfortunately, this rule has not been validated (Level IV CDR), and the potential impact of the rule has not been evaluated. The final clinical decision rule consisted of the following criteria:

1. High-risk mechanism

2. Findings of pain, tenderness to palpation, deformity, or neurologic deficit

3. Age ≥ 60

Future research will be needed to validate this rule in multiple settings, and should be aimed at determining the impact of the rule to ensure it improves outcomes or reduces unnecessary imaging without worsening outcomes. Until then, it seems reasonable to continue using clinical acumen to determine who needs imaging of the thoracic or lumbar spine following blunt trauma, with a lower threshold to at least get plain films in those felt to be at low risk of injury. In patients felt to be higher risk, it seems prudent to forego plain radiography and proceed to CT scanning.

Posted on April 4, 2019 .