What Is Mild Traumatic Brain Injury (mTBI)?
By BrainScope on May 03, 2021

What Is Mild Traumatic Brain Injury (mTBI)?

A traumatic brain injury (TBI) is caused by a bump or impact to the head that disrupts the brain's normal function. According to the CDC, most TBIs that occur each year are mild and sometimes called concussions. Mild traumatic brain injuries (mTBI) can cause changes in brain activity, leading to headaches, fatigue, disorientation, and irritability. A concussion is medically defined as a clinical syndrome characterized by immediate and transient alteration in brain function.

Concussions may be caused by a direct hit to the head, such as falling, contact in sports, or being in an accident. They can also occur due to rapid acceleration-deceleration of the head, such as in whiplash or blast injuries.

Of the estimated 4.8 million head injured people who visit the emergency department (ED) each year in the U.S., 95% are designated as mild. In most cases, such an injury will not lead to long-lasting symptoms. Our brain is covered by the shock-absorbing cerebrospinal fluid (CSF) and incased by thick bone (the skull), designed to protect the brain from serious damage, but can also contribute to brain injury when the brain impacts the skull. There is always a risk that an mTBI can lead to long-term problems or negative consequences in day-to-day life.



What Exactly Does the "Mild" in Mild Traumatic Brain Injury Mean?

Head injuries are common, but the diagnosis of brain injury following a head injury is complicated. Diagnosing mTBI is particularly difficult because of its reliance on subjective, self-reported symptoms and no objective standards. Further, “mild” in mTBI is a misnomer as patients can feel many symptoms. Mild also does not refer to the cause of head injury, as in a seemingly not mild car crash. mTBI is most frequently used interchangeably with a concussion but includes all mild head-injured patients with a Glasgow Coma Scale score of 13-15.

Mild Traumatic Brain Injury symptoms from an mTBI may range from mild to severe and include one or more of the following:

  • Alterations in vision (blurriness, sensitivity to light)
  • Confusion
  • Drowsiness
  • Disorientation
  • A sense of having lost time
  • Difficulty waking up
  • Headaches
  • Loss of consciousness
  • Memory loss (amnesia) of events before the incident or immediately after
  • Nausea and/or vomiting

When to See A Doctor

Medical attention is advised if the patient experiences any of the above symptoms following head trauma. Although it is common to experience headaches and dizziness in the first 24 hours after a head injury, there is always a risk that symptoms may be a sign of something more serious. In rare cases, people with an mTBI can later develop life-threatening bleeding or a blood clot if not promptly diagnosed.

Immediate emergency medical attention is needed if the patient loses consciousness for more than a minute or experiences amnesia lasting more than 24 hours. Any swelling of the head or abnormal changes in behavior should be investigated by a medical professional.

The frequency of occurrence also plays a significant role in mTBI. For example, an athlete who has experienced multiple head injuries may experience life-altering symptoms, such as depression, anxiety, and reduced quality of life.


mTBI-specific Objective Diagnostic Tools

Diagnosing mTBI is complicated as it relies on multiple tools, such as subjective assessment of symptoms based mainly on self-report, and imaging scans which are not sensitive to the full spectrum of mTBI. However, new technology is now available to aid experts in diagnosing mTBI, including concussions, more objectively.

A Decision Support Tool: BrainScope

Innovative technologies, such as BrainScope, can aid in detecting mTBI. It is the only FDA-cleared, non-invasive medical device that can objectively detect the likelihood of both brain bleeds and concussions at the point of care. BrainScope is designed to be fast, accurate, and easy to use. It uses EEG inputs combined with AI-derived algorithms to determine the likelihood of structural and functional brain injury. In addition, this decision support triage tool provides objective measures to evaluate concussions and help medical professionals accurately assess for suspected mTBI. The physician-ordered test is suitable for emergency rooms, athletic departments, the military, and other applications where an early diagnosis of mTBI is sought. BrainScope Structural Injury Classifier (SIC).


BrainScope Structural Injury Classifier (SIC)

The BrainScope Structural Injury Classifier (SIC) is an AI-derived algorithm that evaluates the likelihood of intracranial hemorrhage with 99% sensitivity to intracranial bleeds and 98% negative predictive value (NPV). The SIC is intended for patients ages 18-85, GCS 13-15, and within 72 hours of injury. It also has significantly better specificity than the standard C.T. decision rules (Canadian CT Head Injury Rules & New Orleans Criteria). SIC has been shown to potentially reduce unnecessary head C.T.s in the emergency department by 31% when integrated into the hospital emergency triage workflow.

BrainScope Brain Function Index (BFI)

The BrainScope Brain Function Index (BFI) is an EEG-based algorithm used to assess brain function impairment in patients ages 18-85, GCS 13-15, and within 72 hours following a head injury. The BFI is derived using EEG features that reflect changes in the brain that occur with a concussion, notably including those reflecting disruption of relationships between brain regions (“connectivity”). The Brain Function Index scales with the severity of functional impairment. The lower the BFI, the higher the level of functional impairment.

BrainScope Concussion Index (CI)

The BrainScope Concussion Index (CI) is a multimodal AI-derived algorithm that evaluates the likelihood of concussion in patients 13-25 years of age and GCS 15 at time of injury, over time to aid in recovery and at baseline. The assessment combines EEG data, cognitive performance testing, and observation of specific clinical signs/symptoms. The CI at the time of injury also reflects the severity of the concussive injury, often correlated with rapid or prolonged recovery.

The CI is designed to aid in assessing patients at baseline, injury, and recovery time points. A baseline assessment can help to gauge a patient's possible recovery time. Post-injury, CI assessment provides a quantitative index that can help medical professionals make an essential return to normal activities decisions.


Head injuries are one of the most common reasons for a visit to the emergency department and, in most cases, are not life-threatening. While the skull is designed to protect the brain from lasting trauma, this design is by no means infallible. It is essential to be aware of the brain's vulnerability and err on the side of caution.

Someone who has experienced a blow to the head should be closely monitored for symptoms. If the symptoms described above are present, medical attention should be sought as soon as possible. A comprehensive assessment by a medical professional is the best policy.



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Published by BrainScope May 3, 2021