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Neck injury diagnosis -

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Norman Swan: You heard Ian Harris earlier saying he wouldn't want an MRI of his back for common or garden low back pain. We in fact in Australian waste a fortune in time and money on X-rays, and CT and MRI scans for all sorts of problems, many of which end up in Emergency Departments where the pressure is on not to miss anything.

One situation which strikes terror in the hearts of parents on the sidelines of football or rugby games, first aiders, ambulance officers, doctors and nurses is the neck injury, and not wanting to miss a cervical spine fracture which could lead to quadriplegia.

A study published last week though suggests that there is a fairly simple way to decide who needs to be investigated. They compared two ways of doing this and a Canadian set of rules came out on top.

Professor Chris Maher is a director at the George Institute for Global Health at the University of Sydney.

Chris Maher: We're looking at serious spinal injuries following blunt trauma, so things such as fracture and fracture dislocation, where it's fairly important to get a diagnosis day one.

Norman Swan: What sort of injuries are we talking about?

Chris Maher: The injuring mechanisms are usually car accidents, so whiplash injury, but unfortunately in a small number of people, probably about 2%, they have a serious fracture or fracture dislocation which requires quite different management from a conventional whiplash injury.

Norman Swan: So this is whiplash in the car, you've had a shunting accident, or a kid on the rugby field fallen under a scrum and hurt his neck.

Chris Maher: That's right. So the decision is quite a difficult one for the emergency physician to make. Do they decide that they are going to block up the emergency care department to send this person off for imaging, or can they get them going with some simple pain medication?

Norman Swan: And is it important for the ambulance officer to know this as well?

Chris Maher: Yes, this rule has been implemented with emergency physicians and also with some of the First Aid officers, the ambulance officers.

Norman Swan: You compared two rules here, one is the Canadian C-spine rule and the NEXUS rule. Tell me about these two rules, what are you looking for?

Chris Maher: The two rules essentially look for features from the history and also features from the physical examination. They include very simple items that virtually anybody could assess, and then we are looking through to see what sorts of people we can't exclude the possibility of fracture, and in those group of people, we need to send them off for imaging.

Norman Swan: First of all talk about the NEXUS rule. What are you looking for there?

Chris Maher: The NEXUS criteria are normal alertness, no intoxication, no midline cervical tenderness, no focal neurological deficit...

Norman Swan: That means that you haven't got a weak arm or a weak leg.

Chris Maher: That's right. And no painful distracting injuries, so a fracture somewhere else in the body. And you are hoping that they are all clear so you don't need to order an X-ray or imaging for that person.

Norman Swan: And what are the Canadian C-spine rules?

Chris Maher: It's slightly different, they have a stepped approach. So we look for people who are at high risk of an injury, so older people, people who have had severe trauma, so, for example, a high-speed accident or a rollover, if they've got any of those features they are sent off for immediate imaging.

Then the next is to look for low risk criteria, and then you would test cervical range of motion, so whether the person can rotate to the left and the right 45°. If they can do that they are cleared, they don't need imaging.

Norman Swan: Oh really, it's as simple as that?

Chris Maher: Yes.

Norman Swan: And are there sports injuries which are high risk in the Canadian rule?

Chris Maher: If you had a collapsed scrum or if you landed on your head you need to think about those sorts of people.

Norman Swan: Because ambulance officers would be nervous about asking somebody to move their head to the right or the left.

Chris Maher: That's why you have that stepped approach. So the first thing is you ask whether there is any high risk, and if there is high risk then you would send them off for imaging straight away, or for the ambulance officers you would put them on a backboard or put them in a brace. If you've excluded that, then it is safe to actually try and test range of motion, and it's done actively, so the person would move from side to side. The other thing is that you only apply the Canadian C-spine rule on people who are alert and not intoxicated, because they are a group of people where you couldn't use this rule.

Norman Swan: Is intoxication a higher risk for a cervical fracture?

Chris Maher: I think it's because you don't get a reliable response in someone who's intoxicated with drugs or alcohol.

Norman Swan: Okay, so every parent with a child who plays rugby is listening with great attention now. So you compared the two rules.

Chris Maher: That's right, so we compared the two rules and I guess we got a fairly clear answer, we found that the Canadian C-spine rule was more sensitive and it was also more specific. So in the two ways that we would conventionally look at diagnostic accuracy, the Canadian C-spine rule was the winner I guess.

Norman Swan: And 'the winner' means what?

Chris Maher: In terms of these two tests we're trying to detect a rare condition. We would estimate that people with a blunt trauma to the neck, about 2% of them would have a fracture or a fracture dislocation. And the main thing we are worried about is missing something like that. So these two rules have been set up to be very sensitive and to have low miss rates...

Norman Swan: Which means that you're going to over X-ray in any event.

Chris Maher: That's right. So what we found was that in the direct comparison between these two rules, the Canadian C-spine rule had a sensitivity of 99%, and the NEXUS had a sensitivity of 91%.

Norman Swan: So the Canadian rule picked up more people with a fracture.

Chris Maher: Exactly, and in that head-to-head comparison it only missed one case, whereas the NEXUS missed 15 cases.

Norman Swan: And the X-ray rate? Because that's another important issue because you've got somebody on a backboard, it's slow to move them, you've got to be careful moving them on and off the table, so they do clog up the X-ray department.

Chris Maher: Yes, so compared to a policy of imaging everybody, using these rules does reduce the imaging rate. But there is a substantial false-positive rate. We think that we need to image them but subsequently when we do the imaging test we find out that these people don't have something serious going on. But these rules have been deliberately set up to be very, very sensitive because the consequences of missing a fracture or fracture dislocation, are so disastrous.

Norman Swan: So which test has the greater false-positive rate?

Chris Maher: The greater false-positive rate is with the NEXUS test, and it also misses more. So on both measures of diagnostic accuracy (how many cases are missed and how many false positives) we find that the Canadian C-spine rule is superior. And I think part of the problem is it's sometimes difficult to remember all the features with all these decision rules, and I guess that the good news is that you can get lots of apps available for different smart phones and they'll walk you through it. So there's one from the BMJ which covers the Canadian C-spine rule, it also covers the Ottawa ankle rule, the Ottawa knee rule. And I would expect people to remember that there is a rule, but we are all human and we forget the exact features of the rule.

Norman Swan: The Canadians have been pretty good about these rules, as you've just implied. I mean, the ankle is another part of the body which is over X-rayed.

Chris Maher: Exactly.

Norman Swan: Tell us about the Ottawa ankle rule.

Chris Maher: Well, the Ottawa ankle rules are set up almost exactly the same. They are meant to be highly sensitive so you don't miss an ankle fracture.

Norman Swan: So this is when you go over on your ankle, have you fractured it?

Chris Maher: Yes, have you fractured it? So it's based on different features such as being able to weight bear, whether you've got pain and whether you've got bony tenderness around the ankle. And if you can exclude those problems, it's unlikely you've got a fracture of the ankle and you don't need imaging.

Norman Swan: And I understand you've done some work on whiplash as well.

Chris Maher: Yes, we've worked with the Motor Accident Authority looking at how commonly whiplash is managed by GPs in Sydney. The bad news is that it's very rarely seen by GPs, so to actually remember the rule is probably a big ask for them. They may see one or two cases a year.

Norman Swan: Because the concern would be that you see somebody with a whiplash, they come in, they say they've got a sore neck, the automatic reaction of a GP is, well, I'd better X-ray this to see what's going on.

Chris Maher: Yes. So there is that natural tendency to be conservative, you don't want to miss something, and to order an X-ray, but the reality is that in perhaps 98% of cases it is unnecessary. So if the GP could use the Canadian C-spine rule to make a decision about which people are more likely to need an X-ray, they are going to help the patient, they are going to save them some anxiety, but they are also going to help the healthcare system in terms of saving some money.

Norman Swan: Professor Chris Maher is a director at the George Institute for Global Health at the University of Sydney.