External validation of the modified Brain Injury Guidelines: an observational study

External validation of the modified Brain Injury Guidelines: an observational study

Brain Injury Guidelines, Mild traumatic brain injury, Head trauma

Background Mild traumatic brain injury (mTBI) is a frequent cause of emergency department (ED) admission, with
most cases being uncomplicated. However, a subset of patients presents with intracranial findings on CT, such as
cerebral hemorrhage or skull fracture, that raise concerns for potential clinical deterioration. The modified Brain Injury
Guidelines (mBIG) provide a risk-stratification framework for managing such patients but do not address cerebral
hygromas or indeterminate radiological lesions, both commonly encountered in clinical practice. This study aimed to
externally validate the mBIG criteria, including patients with cerebral hygromas and indeterminate radiological lesions
on CT scan, in order to assess their prognostic accuracy for severe neurological outcomes.
Methods We conducted a retrospective single-center observational study of 451 adult patients presenting to the ED
with a blunt head trauma who underwent initial CT imaging and clinical evaluation. Patients were classified as mBIG
1, 2, or 3 based on CT findings and clinical criteria. Outcomes were extracted from electronic medical records, with the
primary outcome defined as a composite of death due to mTBI, neurosurgical intervention, or admission to intensive
care unit.
Results Among 237 patients classified as mBIG 1, 38.8% exhibited an indeterminate radiological lesion and 35%
had cerebral hygromas. The primary outcome was observed in only one mBIG 1 patient (0.4%; 95% CI: 0.0%–2.3%),
demonstrating high sensitivity (94.7%; 95% CI: 74%-99.9%) and low negative likelihood ratio (0.1; 95% CI: 0.01-0.65),
albeit with wide confidence intervals due to limited sample size. Radiological progression occurred in 6.3% of mBIG 1
patients, though none required neurosurgical intervention or intensive care admission
Conclusion The mBIG criteria appear to be a safe and efficient approach for managing complicated mTBI, even in
cases involving cerebral hygromas and indeterminate radiological lesions. This preliminary validation suggests good
prognostic performance, but further large-scale prospective studies are needed to confirm applicability in routine ED
practice.

Giorgio Colombo1*, Anna Giuliani2

, Francesca Gianni3

, Rosa Casella1

, Giulio Andrea Bertani4

, Giovanni Casazza3
and

Giorgio Costantino3

https://doi.org/10.1186/s12873-025-01454-y

2026

PERI IRAWAN

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