Beyond the Glasgow Coma Scale: New TBI Framework Proposed

After more than half a century, assessment of acute traumatic brain injury (TBI) is getting a makeover.

A newly proposed framework expands assessment of acute TBI beyond the Glasgow Coma Scale (GCS) to include biomarkers, CT and MRI scans, and “modifiers” such as other medical conditions and how the injury occurred.

“Multiple factors prompted this initiative. First was a growing consensus among clinicians, researchers, and patients alike around the need for an improved system for the characterization of TBI,” co-senior author Michael McCrea, PhD, co-director of the Center for Neurotrauma Research at the Medical College of Wisconsin in Milwaukee, told Medscape Medical News.

“Second, was the recognition that a multidimensional framework could better guide individualized treatments that give TBI patients the best chance of survival, recovery, and return to life function.”

“Finally, this movement is now enabled by decades of progress in translational research that informed the components of a multidimensional framework for classification of TBI,” he added.

The proposed framework was published online on May 2src in The Lancet Neurology.

Beyond Level of Consciousness

Since 1974, the clinical TBI severity has been classified according to the GCS sum score as mild, moderate, or severe, based largely on a patient’s level of consciousness.

Given its limitations, in 2src22, the US National Institute of Neurological Disorders and Stroke (NINDS) launched an international initiative to develop a multidimensional classification system for acute TBI.

The so-called “CBI-M framework” is made up of four pillars — clinical, biomarker, imaging, and modifiers — and was developed by TBI experts, implementation scientists, people with lived experience, and partners from 14 countries.

The clinical pillar retains the full GCS total score as a central element of assessment, measuring consciousness along with pupil reactivity as an indication of brain function. The framework recommends including the scale’s responses to eye, verbal, and motor commands or stimuli, as well as the presence of amnesia and symptoms such as headache, dizziness, and sensitivity to noise.

The clinical pillar “should be assessed as first priority in all patients. Research has shown that the elements of this pillar are highly predictive of injury severity and patient outcome,” co-senior author Andrew Maas, MD, PhD, emeritus professor of neurosurgery, University of Antwerp, Antwerp, Belgium, said in a news release.

Other Critical Clues to Recovery

The second pillar uses blood-based biomarkers to provide objective indicators of tissue damage. Measurement of one or more of the following three biomarkers is recommended in the first 24 hours after injury: Glial fibrillary acidic protein, ubiquitin C-terminal hydrolase L1, or S1srcsrc calcium-binding protein B.

The working group noted that this recommendation was based on the diagnostic and prognostic utility of these biomarkers demonstrated in acute care settings. Low levels of each of the three biomarkers accurately indicate a very low risk for traumatic intracranial injury on head CT scans and can be used to rule out the need for CT imaging.

The third pillar of the CBI-M framework is neuroimaging, which offers a “great source” of information about the type and extent of brain injury, the authors reported.

This pillar focuses on CT, the most widely used imaging modality within the first 24 h of injury, but recognizes that MRI is more sensitive than CT and can provide additional information while acknowledging certain practicalities around its use in the acute phase.

The final pillar in the CBI-M framework is “modifiers,” which includes assessment of injury-related factors (how the injury happened) and patient- and society-related factors (such as medications, healthcare access, prior TBI, substance abuse, and living circumstances).

“This pillar summarizes the factors that research tells us need to be considered when we interpret a patient’s clinical, blood biomarker, and neuroimaging exams,” co-first author Kristen Dams-O’Connor, PhD, professor in the Department of Rehabilitation and Human Performance and Department of Neurology, and director of the Brain Injury Research Center at the Icahn School of Medicine at Mount Sinai in New York City, said in the release.

“One example is a patient with underlying cognitive impairment who may require acute monitoring for risk of clinical deterioration, regardless of findings on the initial clinical exam,” she said.

Testing and Validation

The proposed framework is being phased in at trauma centers on a trial basis. It will be refined and validated before it is fully implemented.

The authors of a linked Comment in The Lancet Neurology, led by Junfeng Feng, MD, Shanghai Institute of Head Trauma in Shanghai, China, offer several cautionary notes on the proposed CBI-M framework for acute TBI assessment.

The new assessment model is a “substantial advancement” in integrating the characterization of acute TBI but is “not yet ideal,” they wrote.

In their view, the biomarker pillar is limited in that testing for biomarkers requires time, their specificity for the diagnosis of TBI is not high, and the use of biomarkers is minimal in low-income and middle-income countries.

“Similar to the biomarker pillar, the modifier pillar — an individual’s biopsychosocial characteristics — can be valuable for predicting outcomes in patients with TBI but has minimal effect on decision-making, particularly during the acute phase of TBI,” Feng and co-authors said.

“Another deficiency of the CBI-M framework is that it cannot quantitatively or semiquantitatively assess the condition of patients with TBI yet,” they pointed out.

“To gain recognition and application in countries around the world, the CBI-M framework requires improvement and practical testing through global multicenter, large-scale, prospective cohort studies,” Feng and colleagues cautioned.

Another concern the Comment authors have is that the CBI-M framework does not consider intracranial pressure monitoring, which “should be conducted in specific patients, if possible, and be eventually incorporated into the CBI-M framework for characterization of acute TBI,” they wrote.

Asked why intracranial pressure monitoring was not included in the framework, McCrea said that “while intracranial pressure monitoring is an important element of care for patients in the intensive care unit after TBI, the aim of this movement was to develop a multidimensional framework for characterization of acute TBI across the full spectrum of injury severity and all care settings.”

This research was supported by NINDS, part of the US National Institutes of Health. Disclosures for the