Mild Traumatic Brain Injury (mTBI)

Author(s): Charles E. Levy, MD, Neha Dixit, PhD and David Fitzgerald, MD

Originally published:11/16/2011

Last updated:10/08/2015



Mild traumatic brain injury (mTBI) has been characterized by normal structural imaging, a Glasgow Coma Scale of 13 to 15, loss of consciousness of less than 30 minutes, with altered consciousness < 24 hours, and post-traumatic amnesia < 1 day.


MTBI involves traumatically-induced structural injury or physiological disruption of brain function due to an external force, either from a direct blow, rapid acceleration/deceleration, or transmission of force through the over- and under-pressure waves accompanying blasts.

Epidemiology including risk factors and primary prevention

The Centers for Disease Control and Prevention estimates that 2.5 million Americans survived a traumatic brain injury (TBI) in 2010, 75 to 90% being mTBI. The most common causes are falls (40%), traffic accidents (14%), being struck by an object (15%), and assault (11%). The Defense and Veterans Brain Injury Center estimates that 20% of returning combat veterans have sustained a TBI. Primary prevention of mTBI includes use of seatbelts and helmets, abstention from alcohol and drugs while driving, fall avoidance, and keeping firearms locked and unloaded.


Contact and inertial forces cause linear and rotational acceleration, resulting in increased intracerebral pressure and shear. Shearing forces disrupt fragile structures in the long axis of the brain, primarily axons and small vessels, leading to diffuse axonal injury. On a molecular level, disruption of neuronal membranes causes indiscriminate ion flux, leading to the release of excitatory amino acids. Adenosine-5′-triphosphate (ATP) stores are depleted as the sodium/potassium pump attempts to re-establish equilibrium. ATP is a key compound that provides energy at the molecular level, thus leading to hypofunction and more potentially more permanent damage.

Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)

The immediate symptoms of uncomplicated mTBI include disorientation, headache, blurred vision, dizziness, sleep disturbance, memory, attention and other cognitive difficulties. Typically, symptoms are greatest immediately following the incident, begin to recede within hours, and are gone within days to weeks in the majority of individuals. It is estimated that up to 10% of individuals with mTBI will have chronic symptomatology. Factors associated with persistent complaints include litigation, premorbid chronic pain, psychological difficulties and medical conditions, which exacerbate and complicate recovery. For most, however, complete symptom resolution and return to full activity is expected, with neurological symptoms resolving earlier than neurocognitive symptoms.

Specific secondary or associated conditions and complications

Second-Impact Syndrome is a very rare and avoidable complication that can occur when an individual sustains a second mTBI prior to full recovery from the first. Rapid brain swelling can lead to severe TBI and even death. Chronic traumatic encephalopathy occurs over a period of years following repeated mTBIs or concussive events. Changes in brain architecture following chronic insults can result in neurodegenerative processes and dementia. Post-concussive syndrome (PCS) refers to the persistence/emergence of non-focal neurologic symptoms, (dizziness, headache, cognitive deficits [attention, memory, and judgment]), behavioral changes (irritability, depression, nightmares) and/or sleep disturbance 1 to 3 months after mTBI. Three to 15% are affected. There is not universal agreement on what constitutes PCS. Many of the symptoms of PCS are commonly found in normal individuals as well as those with conditions such as post-traumatic stress disorder (PTSD).



The history should document the mechanism of injury, duration and severity of alteration of consciousness, presence of amnesia prior- or post-trauma, the nature, onset, and time-course of symptoms, (headache, dizziness, weakness, dysesthesias, vertigo, nausea, slurred speech, photophobia), response to treatment, prior head injuries, current and prior psychiatric diagnoses, educational attainment, occupational history, sleep history, and psychosocial risk factors, (i.e., substance use/abuse). Behavioral and cognitive changes should be noted.

Physical examination

The physical examination should include:

  1. neurologic: mental status, cranial nerve, and cerebellar testing; evaluation of tone, strength, sensation, muscle stretch reflexes, and postural stability/balance;
  2. vision: gross acuity, binocular function, and visual fields/attention testing;
  3. examination of the head, neck, and jaw including range of motion, and palpation for focal tenderness versus referred pain.

The following may indicate an acute neurologic condition requiring urgent management: altered consciousness, progressively declining neurological status, pupillary asymmetry, seizures, repeated vomiting, diplopia, worsening headache, disorientation, unusual behavior, confusion, irritability, slurred speech, unsteadiness, weakness or numbness.

Functional assessment

Mobility and self-care dysfunction are not typical. Clinicians should be alert for disorders in thought, judgment, and mood, observe affect and behavior, and also note litigation and compensation issues that may influence behaviors and outcomes.

Laboratory studies

Despite great interest in identifying diagnostic/prognostic biomarkers of mTBI, the promise of this approach has yet to be realized. Although laboratory testing is not necessary to confirm or manage symptoms associated with mTBI, it may be considered for evaluating non-TBI causes (i.e., metabolic disorders, infectious or neuroendocrine) of symptoms.


In the emergency department, a non-contrast head computed tomography (CT) may be indicated for mTBI presenting with certain neurological signs or symptoms suggesting a possible neurosurgical intervention. Abnormalities on standard structural CT or magnetic resonance imaging are not required for the diagnosis of mTBI. A clinical role for functional neuroimaging (positron emission tomography, single photon emission computed tomography,(SPECT) electroencephalography, magnetoencephalography) has yet to be determined. Neuroimaging is not indicated beyond the emergency phase (72 hours post-injury) unless deterioration occurs. The diagnostic potentials of Diffusion tensor (DTI) and SPECT imaging are being investigated, but have not yet been validated for routine clinical use. These two techniques are not needed to make or rule out a diagnosis of mTBI.

Supplemental assessment tools

In persons with excessively prolonged symptoms, full neuropsychologic testing can be of use in guiding cognitive rehabilitation and return to work or school decisions. Cognitive testing may be appropriate for supplemental examination of mTBI symptoms. Succinct cognitive batteries (e.g., Repeatable Battery for the Assessment of Neuropsychological Status [RBANS]; Immediate Post Concussion Assessment and Cognitive Testing [IMPACT]); assessing attention span, verbal memory/learning, working memory, and executive function are useful in determining if everyday cognition is impaired. These tools provide objective quantification of mTBI-related cognitive sequellae, separate from the individual’s self-report.

Early predictions of poor outcomes

  1. Pre-injury: older age, female gender, low socioeconomic status, lower education, lower intellectual functioning, pre-existing mental health conditions (e.g., depression, anxiety, PTSD, substance use disorders);
  2. Peri-injury: lesser social support;
  3. Post-injury: litigation/compensation-seeking, co-morbid mental health conditions, chronic pain, lesser social support.


Accommodations to school and work environments can determine the success or failure of reintegration efforts. Accommodations include: additional time for tasks, quieter work areas, opportunities for breaks and rest, tutors, and assistance in taking notes and completing assignments. Physiatrists should act as advocates, insisting that appropriate accommodations are enacted.

Social role and social support system

Individuals with mTBI, especially those with military-related mTBI, often must deal simultaneously with multiple challenges. In addition to coping with irritability and impaired memory and concentration, they may have to adapt to new social roles requiring flexibility compromised by mTBI. Well-informed and sympathetic family members, friends, teachers and employers can provide emotional and functional support crucial for optimal recovery.

Professional Issues

Litigation/compensation-seeking behaviors are risk factors for poorer outcomes. Some advocate avoidance of the term “mild traumatic brain injury,” fearing it may reinforce disability (this has not been empirically tested). Perceived symptom exaggeration should neither affect the content of clinical care nor prevent the establishment of therapeutic alliances.


Available or current treatment guidelines

Treatment guidelines include a period of rest and observation immediately post injury, treatment of the symptoms (see above), and patient education. Vigorous exercise and high performance activities should be avoided during the initial phase of recovery. Gradual return to work/play is recommended. Athletes must follow specific return-to-play guidelines, including evaluation by medical personnel and a graduated return to play with complete resolution of objective and subjective symptoms. Monitoring individuals for symptom resolution is critical. Pharmacological management of pain, headache and vertigo should be considered. The use of non-steroidal anti-inflammatory drugs for musculoskeletal and headache pain is common. Patients with affective distress may benefit from short-term treatment with selective serotonergic reuptake inhibitors (SSRIs).

At different disease stages

  1. New onset/acute: Immediately following and up to a week post injury, cognitive impairment may be significant. Close monitoring of mental status, rest, education and pain management should speed recovery.
  2. Subacute: One week to 30 days post injury, cognitive and effective symptoms should gradually recede. Continued pharmacological management of pain and affective distress in addition to rest and patient-guided activity is warranted.
  3. Chronic/stable: Beyond 30 days post injury, the brain is reaching a normal metabolic and physiological functioning and patient complaints should be minimal. Remaining symptoms are likely secondary to co-morbid pathologies including pain, depression and PTSD. Aggressive management is indicated. Pharmacological intervention, psychotherapeutic techniques and educational intervention can be effective in improving functional outcome.

Coordination of care

Literature supports a biopsychosocial approach for chronic symptoms/functional complaints. Coordinated interdisciplinary treatment that targets symptoms is recommended. The patient and family are key players. Team members include: physiatrists; occupational, physical, recreational and speech therapists; psychologists; neurologists; psychiatrists; vocational rehabilitation specialists; and social workers. Cognitive rehabilitation programs for mTBI may be beneficial. Short-term psychoeducation in the ED and longer term outpatient programs designed to offer compensation strategies aiming at symptom reduction are often useful.

Patient & family education

Standardized post-concussion education may benefit both patient and family. Mittenberg’s recovery manual1 guides patients and families to attribute symptoms appropriately and in a multifactorial manner emphasizing health as the outcome as opposed to “pathologizing” cognitive and affective distress into disability.

Emerging/unique Interventions

Impairment-based measurement:

Neurocognitive testing that is done acutely and 3 to 6 months later may aid in quantifying residual cognitive impairments. Self-report measures (i.e., Rivermead Post Concussive Symptom Inventory, the Mayo Portland Adaptability Index) may also serve to identify specific affective and cognitive symptomatology. Given the course of mTBI and the common co-morbid conditions of anxiety and depression, it is also important to measure affective distress in the form of health-related quality of life questionnaires and specific psychological questionnaires.

Measurement of Patient Outcomes:

Successful resumption of social and vocational roles often defines success/failure. Self-reported measures of symptomatology, quality of life and health-related distress are also useful outcome measures; administration at baseline and follow-up documents the effectiveness of treatment.

Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills

Almost all returning combat veterans who have been exposed to significant blasts have also been exposed situations that could incite PTSD. Common to both PTSD and mTBI are disturbances in sleep. Because these conditions so often co-occur and because there is such a great overlap in their symptoms, it can be very difficult to tease these diagnoses apart. Clinicians should pursue sleep issues and should treat symptoms regardless of diagnosis.


Cutting edge concepts and practice

Emerging interventions include the use of secure, encrypted distance technology (computers/videophones) to conduct cognitive and psychotherapy for those remote to the medical center. Smartphones, personal digital assistants, and voice recorders are being used to provide cognitive cues and to function as organizer/memory/navigation aids. The non-profit Wounded Warrior Project has developed an educational/life skills program for eligible U.S veterans with at least 20% service-connected disability related to service in Iraq and Afghanistan. Unit cohesion is used to maximize individual achievement. Students live together, and have structured routines including a college curriculum and vocational placement.


Gaps in the evidence-based knowledge

Most of what we know about the likelihood, extent, and time-course of recovery from mTBI comes from athletic concussions. It is not yet clear how generalizable this is to returning combat veterans diagnosed with mTBI. Differences include the contexts in which the injuries occur, as well as the point at which they are evaluated. Athletic concussion occurs within the confines of the playing field, with immediate medical attention available. Protocols require removal from play and a period of rest followed by a graded return to sports activity. In contrast, the most common cause of current combat mTBI are blasts, occurring unpredictably, which punctuate extended periods of elevated stress and sleep deprivation. Repeated exposures may occur over periods of months or years. Likewise, evaluation often occurs months or years after the event, with the diagnosis relying on veterans’ recall of events long past.

Although hyperbaric oxygen therapy has been advocated for TBI treatment, randomized controlled trials with placebo treatments have not demonstrated any improvement attributable to hyperbaric oxygen treatment.


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Original Version of the Topic

Charles E. Levy, MD

Author Disclosure

Charles E. Levy, MD
Nothing to Disclose

Neha Dixit, PhD
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David Fitzgerald, MD
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