1. HEAD CT DECISION RULES – WHO TO SCAN?
EMC SDMH 2015

2. Objectives
Understand rationale for developing and using a clinical decision rule for Head CT
Compare Adult Head CT rules – Canadian CT head Rule;
New Orleans Criteria;
NEXUS II
Compare Paediatric Head CT rules – CHALICE
PECARN

3. MINOR HEAD inJURY Defined as presenting GCS 14-15
Incidence of ‘clinically important’ brain injury ~ 1%
Incidence of abnormal head CT ~ 5- 6%
Neither ethical nor cost effective to scan everyone
US CT rates up to 80% of minor head injury!
Rules need to ensure patients are not missed (i.e have high sensitivity)
High sensitivity rules generally NOT specific by definition

4. COMMON HEAD CT RULES CANADIAN CT HEAD RULE NEW ORLEANS CRITERIA
NEXUS II
Evidence skull #
Scalp haematoma
Neurological deficit
Recurrent vomiting
Age > 65
Altered level of alertness
Abnormal behaviour
GCS < 15 at 2 hrs after injury
Suspected open/depressed skull #
Signs of basal skull #
Vomiting > 1 episode
Age > 65
Retrograde amnesia >30 mins
Dangerous mechanism
Excluded patients on warfarin; abnormal neurological findings, and those with seizures (scanned)
Headache
Seizure
Visible trauma above the clavicles
Vomiting
Age > 60
Persistent anterograde amnesia
Intoxication

5. HOW Do ThEY PERFORM CCHR and NOC – 99-100% sensitive
NEXUS II 97% sensitive
CCHR more specific (40-50%) than NOC (12%) and NEXUS (47%)
CCHR reduced need for CT by 48% vs NOC (12%)
Canadian authors believed introduction of NOC would have increased their baseline scanning rate!

6. CuRRENT PRACTICE NSW State guideline
Increase sensitivity by summing all identified risk factors
?specificity

7. Paediatric Head CT rules
Paediatric assessment potentially more difficult
Non-verbal, or poor localisation
Minor head injuries common in toddlers!
High level of parental anxiety
Risk of TBI low however
PECARN series – abnormal CT 5.2%, ciTBI 0.9%
CHALICE series – abnormal CT 1.2% ciTBI 0.6%
Risks from radiation higher than in adults
Poorer educational performance
Estimated additional risk malignancy 1:1500 in 1 yr old

8. CHALICE – ‘High Risk’ Criteria
MECHANISM AND HISTORY
EXAM
High speed MVA > 64km/hr
Fall >3m
High speed impact
LoC >5 min
Amnesia > 5 min
Abnormal drowsiness
3 or more vomits
Suspicion of NAI
Seizure in non-epileptic
GCS <14, or <15 if under 1yr age
Suspicion of skull fracture
Tense fontanelle
Positive focal neurology
Bruise swelling or laceration >5cm if <1 yr of age
 ANY feature positive treated as indication for CT

9. PECARN – ‘low risk’ criteria
PECARN - <2 yrs old
PECARN - >2 yrs old
GCS < 15
Altered Mental status
Palpable skull fracture
CT Head (4.4% risk ciTBI)
Non-frontal scalp haematoma
LoC > 5s
Severe mechanism
Car vs pedestrian/bike
Fall>1m
Head struck by high speed impact
Abnormal behaviour per parents
 Observe or CT Head (0.9% risk of ciTBI)
GCS < 15
Altered mental status
Signs of basilar skull fracture
CT Head (4.3% risk ciTBI)
History of vomiting (>1)
LoC
Severe mechanism
Car vs pedestrian/bike
Fall >2 m
Head struck by high speed impact
Severe headache
Observe or CT Head (0.9% risk of ciTBI)

10. CHALICE VS PECARN Rule –in rule vs Rule-out rule.
PECARN only rule externally validated in literature
Would you scan a 2 yr old on CHALICE criteria?
Recent study at Tertiary Childrens Hospital Australia
19% CT scan rate – 1.4% ciTBI (intervention)
CHALICE predicted 46% scan rate (303 children not scanned) – 4 missed positive scans, none requiring intervention.
PECARN 100% sensitive, 100% NPV for <2
PECARN 96.8% sensitive, 99.95% NPV for ciTBI >2
CHALICE 98% sensitive, 87% specific in trial (but not validated)

11. Questions?

12. SUMMARY
Head CT needs to balance risk vs benefit and resource utilization
All current Head CT clinical decision rules seem to offer good sensitivity
Canadian Head CT rule currently appears to be best clinical decision rule in adults in terms of specificity and efficient resource use
PECARN appears to have strongest evidence for utility in ED for pediatric use, but rules not directly comparable
Be aware that NSW guidelines tend to be summative of existing rules