Head injury in children

NICE NG232 (2023, replaces CG176); PECARN head injury rules (Kuppermann, Lancet 2009); ACR AC Head Trauma (2021)

The decision rule matters more here than anywhere else, because the balance between a missed injury and a lifetime radiation risk is at its tightest. Where the rule indicates imaging the study is an unenhanced CT with paediatric parameters.

Blunt head injury in a child or young person, ranging from a low-mechanism fall in a well toddler to a high-mechanism injury with a reduced conscious level.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Haemodynamic state

The fact that lets a pathway waive its own requirements. A crashing patient does not wait for a score.

GCS

Focal neurological deficit

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

CT Head — Unenhanced

CT Head

What we'd amend, and why

This step is conditional on a positive decision rule, and the condition is the clinically important half of it: PECARN and NICE NG232 both define a very low risk group in whom observation, not CT, is the recommended course, and a well child who fails the rule should be observed rather than scanned. When the rule IS positive, the study has to be one that a distressed child will tolerate without sedation and that answers the surgical question immediately: unenhanced CT does both in seconds. The counterweight is that the developing brain is the most radiosensitive tissue this service scans and these children have the longest remaining life over which a risk can express itself, which is why the selection rule and paediatric dose parameters are as much part of the study as the acquisition.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwaypaeds — Children and young people
rulerule-paeds-dose — Child-sized technique and contrast dose; checked by Radiographer at the scanner
rulerule-paeds-sedation — Sedation or anaesthesia for a child; checked by Nurse before the scan

Decision support only. Local protocol takes precedence.

Handled at the scanner(1)nothing for you to do

Settled and owned downstream. Each returns to a radiologist only on the stated trigger.

Child-sized technique and contrast dose
Confirm that a size- or weight-based protocol is selected — child-sized kV and mAs against size-based diagnostic reference ranges — and that contrast volume is calculated by weight rather than taken from an adult default. Weight-based iodinated contrast volumes of roughly 1.5–2.0 mL/kg are widely used in paediatric CT.
Radiographer at the scannerAt the scanner
Flags back if: No paediatric or size-based protocol exists on the scanner for the requested examination, or the requested coverage or number of phases exceeds what the clinical question needs — for example a multiphase study where a single phase answers it, or whole-body coverage for a focal question.
Dose optimisation must never become a reason to delay a scan that the decision rule has indicated. The protocol is selected at the scanner by the radiographer using age- and weight-banded parameters, which is a routine step and not a vetting blocker.

Worth asking the referrer (3)

None of these hold the request up. They sharpen the protocol or the plan that follows.

Has a validated decision rule been applied — PECARN, or the NICE NG232 criteria — and which specific feature is positive?
It is the indication. A child who falls in the very low risk group of a validated rule has a probability of clinically important traumatic brain injury well under one in a thousand, and structured observation performs at least as well as immediate imaging; scanning that child delivers a dose to the most radiosensitive tissue this service images, in the patient with the longest remaining life over which a risk can express itself. Naming the positive feature — reduced GCS, suspected skull fracture, focal deficit, seizure, repeated vomiting, a non-frontal scalp haematoma in an infant, a dangerous mechanism — is what separates the scan that is indicated from the scan that is reflex.
How long has the child been observed, and are the symptoms improving or progressing?
Observation is the comparator to CT in the low-risk child, not a delay before it. A child several hours out from the injury who is improving is in a different risk category from one who has just arrived, and both NICE and PECARN allow observation as the plan rather than the wait.
Is the injury consistent with the stated mechanism, and is the child developmentally capable of it?
An inconsistent history, or any significant injury in a non-mobile infant, moves the child onto a safeguarding pathway with different imaging, different documentation and a skeletal survey outside this card.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Reduced conscious level, focal deficit or haemodynamic instability — scan now

Role	Study & protocol	Why this answers the question
First line	CT Head CT Head — Unenhanced usually appropriate	This child is rule-positive on the features that PECARN and NG232 weight most heavily, so the caution that governs the rest of this card — that observation, not CT, is the recommended course for the very low risk group — is addressed to a different patient and does not apply here. An altered mental status, a focal deficit or a shocked child after head injury sits at the top of both rules, and the balance that makes paediatric CT a considered act tips decisively: the lifetime attributable risk is real and it is smaller than an expanding extradural. Scan immediately, with age- and weight-banded parameters selected by the radiographer at the scanner, and do not let dose optimisation become a queue. A haemodynamically unstable child is resuscitated on the way, and an isolated head injury is a rare cause of shock in a child — look for the bleeding elsewhere.
Second line	MRI Brain MRI Brain — routine unenhanced	Afterwards and once the child is stable, for characterising what the CT showed, for suspected diffuse axonal or hypoxic injury, and for dating collections in a safeguarding assessment. Substituting it acutely in an unstable or obtunded child loses time and fracture detection at once.

The observation alternative belongs to the very low risk group and is deliberately absent from this arm. Offering it here would be the mirror image of scanning a well child.

Children and young people

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	CT Head CT Head — Unenhanced usually appropriate	This step is conditional on a positive decision rule, and the condition is the clinically important half of it: PECARN and NICE NG232 both define a very low risk group in whom observation, not CT, is the recommended course, and a well child who fails the rule should be observed rather than scanned. When the rule IS positive, the study has to be one that a distressed child will tolerate without sedation and that answers the surgical question immediately: unenhanced CT does both in seconds. The counterweight is that the developing brain is the most radiosensitive tissue this service scans and these children have the longest remaining life over which a risk can express itself, which is why the selection rule and paediatric dose parameters are as much part of the study as the acquisition.
Second line	MRI Brain MRI Brain — routine unenhanced	Not an emergency substitute, but the right study once the child is stable: for characterising injury seen on CT, for suspected diffuse axonal or hypoxic injury, and as part of a safeguarding assessment where the age of a collection matters. Rapid unsedated sequences are increasingly used in cooperative or sleeping children to avoid a repeat CT.

This pathway describes what to image WITH once a validated rule is positive. It does not say that every child with a head injury is imaged: PECARN and NICE NG232 both define groups in whom the recommended course is structured observation, and the very low risk groups carry a probability of clinically important traumatic brain injury well under one in a thousand.
Observation is an active decision, not a failure to decide. For the very low risk group a period of structured observation performs at least as well as immediate imaging, and NICE offers it explicitly as an alternative for the child with a single risk factor.
The conscious level, the mechanism and the rule score cannot be read from the request in this tool, so the rule is put to the referrer as a clarifier that travels with every decision rather than as a pathway fork or a blocking question. Holding every paediatric head injury request until a score is supplied would delay the children who genuinely need the scan.

Pitfalls

Scanning a well child who falls into the very low risk group of a validated rule, where observation is the recommended course. This is the commonest and most consequential error on this card: PECARN puts the risk of a clinically important injury in that group at well under one in a thousand, and the CT is not a neutral act.
Reading "CT head is first-line" as "CT head is indicated". It is first-line for the child the rule has selected; for the child the rule has excluded, the first-line answer is observation.
Accepting a request whose entire indication is "head injury" without asking for the mechanism, the conscious level, vomiting, the scalp haematoma and the observation so far — the exact items the rule is built from.
Applying adult dose parameters, which delivers several times the necessary exposure for no diagnostic gain.
Missing the significance of a non-frontal scalp haematoma in an infant, which is a specific risk feature in the under-twos.
Failing to raise safeguarding when the mechanism does not explain the injury or the child is not yet mobile.
Substituting MRI acutely in an unstable child and losing time and fracture detection in the process.

Priors — what to pull first

Any prior imaging is important in safeguarding assessment, where collections of different ages are the key observation.
In a child with a shunt or a known craniofacial anomaly, retrieve the baseline before interpreting ventricular size or bony contour.

What makes a good request

CT here is indicated by a positive decision rule, not by the fact of a head injury. The first-line study on this card is what to do WHEN the rule is positive; it is not a recommendation to scan every child who has hit their head, and the commonest vetting error on this indication is to read it as one.
The PECARN rules, derived and validated by Kuppermann and colleagues in more than 42,000 children, stratify separately below and above the age of two. Under two the very low risk group is normal mental status, no scalp haematoma other than frontal, no or very brief loss of consciousness, a non-severe mechanism, no palpable skull fracture and normal behaviour according to the parent; at two and over it is normal mental status, no loss of consciousness, no vomiting, a non-severe mechanism, no clinical signs of basal skull fracture and no severe headache. In both groups the risk of a clinically important traumatic brain injury is well under one in a thousand, and the rule explicitly recommends observation rather than CT.
NICE NG232, which replaced CG176, sets out an equivalent structure for the United Kingdom with a distinct set of features for children under one year, and likewise offers a period of structured observation as an alternative to immediate imaging for the child with a single risk factor.
A request that states only "head injury" cannot be triaged. The rule needs the mechanism, the age, the conscious level, the presence and location of any scalp haematoma, vomiting, and the period of observation so far — and where those are absent the right response is to ask, not to scan.
Injury inconsistent with the stated mechanism, or in a non-mobile infant, raises safeguarding questions that change the imaging protocol and involve a skeletal survey pathway outside this card.

Scoring this once it is done

The classification and risk tools this question ends in.

PECARN Pediatric Head Injury Rule Canadian CT Head Rule (CCHR)Marshall CT Classification (TBI)Rotterdam CT Score (TBI)

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

CT Head — Unenhanced MRI Brain — routine unenhanced

Confirm locally

CT Head — Unenhanced: timings are typical — confirm against local protocol.
Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.