CT Imaging in Minor Head Injury

For minor head injury patients (GCS 13-15) apply the CCHR or NOC decision making tools to help you decide if a head CT is required.

Canadian CT Head Rule:

Head CT is only required in minor head injury patients with any one of the following:

High Risk Factors (for neurological intervention)

  •  GCS score <15 at 2 h after injury
  • Suspected open or depressed skull fracture
  • Any sign of basal skull fracture (haemotympanum, ‘racoon’ eyes, cerebrospinal fluid otorrhoea/rhinorrhoea, or Battle’s sign)
  • Vomiting ( > two episodes)
  • Age 65 years

Medium Risk Factors (for brain injury on CT)

  • Amnesia before impact >30 min
  • Dangerous mechanism (pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from height >3 feet or five stairs)

But the Rules Don’t Apply If:

  • GCS < 13
  •  Patient taking coumadin or had a bleeding disorder
  • Obvious open skull fracture
  • Age < 16 yo
  • Non-traumatic

MDCalc: Canadian CT Head Rule Tool

New Orleans Criteria: 

Presence of one or more of the following seven findings requires a head CT:

  • Headache
  • Vomitting
  • Age > 60 yo
  • Drug or alcohol intoxication
  • Deficits in short-term memory
  • Physical evidence of trauma above the clavicles
  • Seizure

MDCalc: New Orleans Criteria Tool

To CT or Not to CT That Is the Question: CT Imaging in Minor Head Injury

SMART EM Podcast – Minor Head Injury: Who Has the Badness?

I’m a huge fan of these folks! If you have the time I definitely recommend having a listen.

Last week I saw a motor cycle crash patient. Nothing urgent or too fancy, just a simple accident to start a night in the ED on my first shift of an emergency ultrasound elective. I thought I’d get to practice my FAST exam, maybe sew up a few lacs, or so I thought….

As I sit down to interview the patient, I smell alcohol (Great. That explains the cop standing next to the door). An impaired patient interview and physical exam is not the uncomplicated lac repair/ultrasound practice I was looking for, but I’m already here so might as well get some practice. I ask about the accident; 30-35 mph, single vehicle accident, no impact (other than the ground). So far so good. He has a cut on his head, so I ask about his helmet. No helmet. Really? My uncomplicated case just got more complicated. I continue. Just a little head pain (2/10). Not terrible. He’s not sure about loss of consciousness, “I don’t think so, but maybe.” Ugh. Not helpful. He has back pain too. Not good either. I round my way to medical history and things get complicated again. Of course he has a mechanical heart valve. And is taking Coumadin. Why not? My simple ultrasound practice case is no more.

I do a physical exam. No obvious head abnormalities, other than a small cut on his forehead. He’s positive for tenderness over his thoracic and lumbar spine. Neuro exam is normal (for a drunk guy). Physical exam done.  I pull my thoughts together and present the case to the attending. I take a deep breath and start, “45 year old male presents with… ” I finish and mentally pat myself on the back. Success! As a new-to-seeing-patients med student, small successes like a good patient presentation make me do a little happy dance.  He says, “Okay. What would you do next?” Oh crap. I know he needs blood tests (especially an IRN & PT given his Coumadin) and definitely X-Rays given the spinal tenderness, but does he need a head CT? He’s borderline to me. 2/10 head pain, normal neuro exam, and he was only going about 30 mph. On the other hand, he wasn’t wearing a helmet, he’s a little drunk (not a lot), and taking Coumadin. Does he need a head CT?

The Canadian CT Head Rule & New Orleans Criteria to the Rescue!

For minor head injury patients (GCS 13-15) apply the CCHR or NOC decision making tools to help you decide if a head CT is required.

Canadian CT Head Rule:

Head CT is only required in minor head injury patients with any one of the following:

High Risk Factors (for neurological intervention)

  •  GCS score <15 at 2 h after injury
  • Suspected open or depressed skull fracture
  • Any sign of basal skull fracture (haemotympanum, ‘racoon’ eyes, cerebrospinal fluid otorrhoea/rhinorrhoea, or Battle’s sign)
  • Vomiting ( > two episodes)
  • Age 65 years

Medium Risk Factors (for brain injury on CT)

  • Amnesia before impact >30 min
  • Dangerous mechanism (pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from height >3 feet or five stairs)

But the Rules Don’t Apply If:

  • GCS < 13
  •  Patient taking coumadin or had a bleeding disorder
  • Obvious open skull fracture
  • Age < 16 yo
  • Non-traumatic

MDCalc: Canadian CT Head Rule Tool

New Orleans Criteria: 

Presence of one or more of the following seven findings requires a head CT:

  • Headache
  • Vomitting
  • Age > 60 yo
  • Drug or alcohol intoxication
  • Deficits in short-term memory
  • Physical evidence of trauma above the clavicles
  • Seizure

MDCalc: New Orleans Criteria Tool

Remember the Glasgow Coma Scale?

–          Rates eye opening, motor response, verbal response to assess consciousness

–          If GCS score is < 15, note the score for each section (e.g. GSC 13 E4M5V4)

–          You have to know patient’s GCS to apply the CCHR or NOC rules

–          Don’t remember the GCS specifics? Here you go…

Eye Opening
Score 1 Year or Older 0-1 Year
4 Spontaneously Spontaneously
3 To verbal command To shout
2 To pain To pain
1 No response No response
Best Motor Response
Score 1 Year or Older 0-1 Year
6 Obeys command
5 Localizes pain Localizes pain
4 Flexion withdrawal Flexion withdrawal
3 Flexion abnormal (decorticate) Flexion abnormal (decorticate)
2 Extension (decerebrate) Extension (decerebrate)
1 No response No response
Best Verbal Response
Score >5 Years 2-5 Years 0-2 Years
5 Oriented and converses Appropriate words Cries appropriately
4 Disoriented and converses Inappropriate words Cries
3 Inappropriate words; cries Screams Inappropriate crying/screaming
2 Incomprehensible sounds Grunts Grunts
1 No response No response No response

Special Circumstances with GCS scores:

Intubated Patients…

–          Intubated patients can’t be scored for the Verbal section

–          Rated out of 10T points (T indicates intubated)

–          Minimum score 2T, maximum score 10T

Occular Trauma Patients…

–          Eye injury sometimes interferes with scoring the Eye Opening section

–          Rated out of 11C points (C indicates closed eyes)

–          Minimum score 2C, maximum score 11C

MDCalc: Glasgow Coma Scale Tool

So What’s the Big Deal?

Mild traumatic brain injuries are common, but the consequences of missing a serious brain injury can be life threatening. Why is that? Well I’m glad you asked. The brain is housed in an inelastic container (the skull) that has limited room for expansion. In the event of a brain injury, swelling or bleeding can cause a rapid increase in intracranial pressure. Increased intracranial pressure leads to extreme cases of badness and can result in long-term neurological damage or death. With so little room to expand brain badness can happen fast!

Ok. So a positive CT exam is bad, but these are minor head injury patients. How often does that really happen? In the Canadian CT Head Rule study, 8% of minor head injury patients had clinically significant brain injuries and 1% required neurological intervention. That means that 2 out of 25 mild head injuries will have clinically significant brain injuries AND 1 in 100 are going to need neurological interventions. That’s a quite a few patients.

Common causes of traumatic brain injuries include motor vehicle collisions, falls, assaults, sports-related injury, and penetrating trauma. So keep an eye out for minor head injuries if you seen these.

 Images from Radiopaedia

Show Me the Evidence

What the Canadians say…

–          Minor head injury defined as a GCS of 13-15 and a history of loss of consciousness, amnesia, or disorientation

–          Out of 3121 study subjects 8% had clinically important brain injury and 1% required neurological intervention

–          High risk factors were 100% sensitive and 68.7% specific for predicting neurological intervention. Only 32% of patients were required to undergo a CT scan.

–          Medium risk factors were 98.4% sensitive and 49.6% specific for neurosurgical intervention. Only 54% of patients were required to undergo a CT scan.

Basically:

–          If you apply these rules, you’ll catch the clinically important brain injuries and will scan less people in the process.

–          A good number of minor head injury patients will have clinically important brain injuries.

What the New Orleans folks say…

–          Minor head injury defined as a loss of consciousness in patients with a normal neurologic exam and GCS score of 15

–          Out of 502 patients with minor head injury 6.9% has positive CT scans

–          Having at least one of the seven risk factors was 100% sensitive and 25% specific

–          All patients with positive CT scans had at least one of the seven risk factors. None of the patients without at least one of the seven risk factors had a positive CT scan.

Basically:

–          If you apply these rules, you should catch all minor head injury patients who have positive CT scans!

What the “Other Guys” Say… A Study Comparing CCHR and NOC

–          NOC and CCHR both result in lower CT rates (CCHR 88% reduction; NOC 52.1%)

For predicting need for neurosurgical intervention:

–          NOC and CCHR were both 100% sensitive (awesome!)

–          CCHR was more specific (76.3%) than NOC (12.1%)

For predicting clinically important brain injury:

–          NOC and CCHR were both 100% sensitive (again awesome!)

–          CCHR was more specific (50.6%) than NOC (12.7%)

Applying the Rules to Our Patient

Let’s think back to our patient. GSC of 15, normal neuro exam, head pain is 2/10, unlikely but possible LOC. Intoxicated but not too badly. He crashed his motor cycle going 30ish mph, but had no helmet. Physical exam showed a small head laceration. Does he need a head CT?

The Canadian Guidelines:

–          Doesn’t apply because of Coumadin use… get a head CT!

–          Let’s pretend there’s no Coumadin involved. What risk factors does he have?

–          Dangerous mechanism, maybe. A motor cycle crash with no helmet sounds significant to me. It’s not specified on the CCHR dangerous mechanism list, but I think a helmetless motor cycle crash would probably count. Let’s get that man a CT!

The New Orleans Guidelines:

–          What risk factors do we see now?

–          Headache (a minor one), evidence of trauma above the clavicles, and alcohol intoxication. He definitely qualifies for a CT!

After looking at both guidelines, I would definitely order a head CT for this case. The patient received a head CT under the Canadian guidelines because of his hypo-coagulative state (Coumadin). If there wasn’t Coumadin involved, he still would have gotten a CT for his dangerous mechanism of injury. The patient received a head CT under the New Orleans guidelines because he had a headache, evidence of trauma above the clavicles, and was intoxicated. Both guidelines are excellent decision making tools that add helpful information when deciding if a minor head injury patient needs a head CT. While neither guideline should serve as a substitute for clinical judgment, both provide valuable evidence-based information to enhance the decision process in evaluating the need for CT scans in minor head injury patients.

References:

Canadian CT Head Rule

Stiell IG, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001 May 5;357(9266):1391-6. PubMed PMID: 11356436.

New Orleans Criteria

Haydel MJ, et al. Indications for computed tomography in patients with minor head injury. N Engl J Med. 2000 Jul 13; 343(2):100-5.

Comparing the Canadian CT Head Rule and the New Orleans Criteria

Stiell IG, et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA. 2005 Sep 28; 294(12):1511-8.

“Head Injury” Medscape

Olson DA, September 5, 2012. Head Injury, Medscape. http://emedicine.medscape.com/article/1163653-overview. (September 24, 2012)

“Traumatic Brain Injury” UpToDate

Hemphill JC, Phan N, July 5, 2012. Traumatic Brain Injury: Epidemiology, Classification, and Pathophysiology, UpToDate. http://www.uptodate.com/contents/traumatic-brain-injury-epidemiology-classification-and-pathophysiology. (September 24, 2012)

Compiled by: Jennifer Cotton

Miss anything? Forgot to include something important? Leave a comment and help us improve our knowledge base for medical students!

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