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    Patent Pending

    Pediatric NEXUS II Head CT Decision Instrument for Blunt Trauma

    Predicts need for head CT after pediatric blunt head injury, similar to PECARN.


    Use in patients <18 years old who have sustained blunt head trauma within the past 24 hours and in whom head CT is being considered. 

    Note: We recommend using PECARN over other pediatric head trauma rules, as it is the most widely validated (see Next Steps for details).

    When to Use
    Why Use

    Patients <18 years old who have sustained blunt head trauma within the past 24 hours and in whom head CT is being considered.

    • Only patients for whom the clinician was going to perform a head CT (regardless of the decision tool result) were included in the study.

    • May not have adequate sensitivity in patients with high GCS scores (14-15), as GCS scores were not reported.

    • Outcomes of those who did not have head CT performed based on clinical gestalt are not known.

    • The validation study included only 35% male patients, which is in stark contrast to previous studies that have found boys were more likely to present with head injuries (64.8%, 65%, and 62% of patients were male in CATCH, CHALICE, and PECARN respectively).

    • The study population was substantially older compared to those for previous decision instruments (11.9 years, versus 7.1 years in PECARN).

    • Because this study did not enroll patients who did not undergo head CT, no firm conclusions can be made regarding whether this decision instrument would have satisfactory sensitivity and/or reduce head CT imaging in ALL pediatric patients with head trauma.

    May safely reduce use of head CT imaging (derivation and validation showed 100% sensitivity for identifying patients requiring neurosurgical intervention, with subsequent reduction in head CT of 25% and 34%, respectively).


    Diagnostic Result:

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    Next Steps
    Creator Insights


    • In low risk populations, we would recommend using other externally validated tools to determine the necessity of head CT in pediatric blunt head trauma patients (i.e., PECARN).
    • Our recommendation for the PECARN Head Injury Algorithm is based partly on the fact that it enrolled the largest number of patients during its derivation and validation (33,785 in derivation cohort and 8,627 in the validation cohort). This compares to 22,772 enrolled in the original CHALICE study, 3,866 patients for the CATCH Rule, and 1,018 subjects enrolled in Pediatric NEXUS II Head CT instrument.
    • PECARN also has the highest negative predictive value (NPV) (100% and 99.95% for children <2 and ≥2 years-old, respectively). That said, the NPV of the CHALICE (99.8%) and CATCH (99.9%) rules are also excellent and present additional reasonable options.


    • Patients who do not meet criteria for imaging should always be counseled about the following:
    • Concussion and its symptoms.
    • Strict head injury return precautions (e.g. vomiting, somnolence/altered mental status).
    • Many still recommend a period of observation after head injury.


    • Patients who meet criteria for head CT may have intracerebral hemorrhage or they may not; however, if the criteria of the instrument are met, head CT is recommended.

    Critical Actions

    Remember, this decision instrument was only applied to a population of pediatric patients in which clinicians were intending on performing head CT. This may have eliminated a clinically “low risk” group of patients (i.e., GCS 15). Thus, applying this instrument to this population is not recommended.

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    About the Creator
    Dr. William R. Mower
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