The acronym MTBI stands for Mild Traumatic Brain Injury, a condition that occurs when an external force causes a temporary disruption of normal brain function. It is used interchangeably with the term concussion, representing the most frequent type of brain injury seen in healthcare settings. An MTBI involves a transient alteration in mental status that is not due to a more severe injury like a brain bleed or skull fracture.
Defining the “Mild” in Mild Traumatic Brain Injury
The term “mild” refers primarily to the initial severity of the injury and the patient’s neurological status, not the severity of the symptoms a person might experience. In medical classification, an MTBI is typically defined by a score of 13 to 15 on the Glasgow Coma Scale (GCS) following the injury, indicating a relatively high level of consciousness. The injury mechanism involves a biomechanical force that causes the brain to move rapidly within the skull, leading to a temporary energy crisis within the brain cells.
This process disrupts the normal functioning of neurons, often resulting in axonal injury at the cellular level, rather than causing large-scale structural damage such as bruising or tearing of tissue. Unlike moderate or severe traumatic brain injury (TBI), an MTBI typically does not involve an extended period of unconsciousness or visible abnormalities on a standard computed tomography (CT) scan.
Common Causes and Risk Factors
Mild traumatic brain injuries result from a sudden blow, bump, or jolt to the head, or from a rapid acceleration and deceleration of the body that causes the brain to impact the inside of the skull. The most common causes of MTBI across all age groups is unintentional falls, particularly in older adults and young children. Motor vehicle accidents are another major source, where whiplash forces can cause the brain to shift even without a direct strike to the head.
Sports-related impacts, especially in contact sports like football, soccer, and hockey, frequently result in concussions. Other causes include physical assaults and blast injuries, which are often seen in military personnel. Individuals in high-risk groups, such as young adults between the ages of 15 and 24, are more likely to experience an MTBI due to these common mechanisms.
Recognizing Immediate Signs and Symptoms
Symptoms of an MTBI can vary widely and may not be immediately apparent after the injury. Symptoms are grouped into three categories: physical, cognitive, and emotional/sleep disturbances. Physical symptoms frequently include a headache that may feel like pressure, nausea or vomiting, dizziness, and problems with balance or coordination. Individuals also report sensitivity to light or noise and feeling generally fatigued or drowsy.
Cognitive changes often manifest as a feeling of being “foggy” or mentally slowed down, along with confusion, difficulty concentrating, or trouble remembering new information. Emotional and sleep-related symptoms include increased irritability, anxiety, sadness, and changes in sleep patterns, such as sleeping much more or much less than usual. In some cases, there may be a brief loss of consciousness, though this is not required for a diagnosis. It is important to note that these symptoms can develop hours or even days after the initial incident, making a period of observation necessary.
Initial Medical Evaluation and Management
Following a suspected MTBI, seeking medical attention is important for a thorough evaluation and to rule out more severe injuries. Patients are assessed using a neurological exam, and the Glasgow Coma Scale (GCS) score is often used to quickly classify the injury severity, with scores of 13 to 15 confirming the “mild” classification. However, immediate emergency medical attention is necessary if a person experiences a worsening headache, repeated vomiting, seizures, or increasing confusion, as these are warning signs of a potential life-threatening complication.
To check for skull fractures or acute internal bleeding, a computed tomography (CT) scan is commonly performed in the emergency setting due to its speed and ability to detect blood. In uncomplicated MTBI, the CT scan typically appears normal, as the injury is primarily functional rather than structural. Magnetic resonance imaging (MRI) is more sensitive to subtle soft tissue changes but is rarely used acutely unless symptoms persist or the CT scan is normal but concerns remain.
The initial management plan focuses on a short period of relative physical and cognitive rest, usually lasting 24 to 48 hours. The medical recommendation is to avoid strict, prolonged rest, which can potentially worsen outcomes. After the initial rest period, a gradual, structured return to daily activities is advised, with the individual avoiding activities that cause symptoms to worsen. This “watchful waiting” period, with close monitoring for any developing or worsening symptoms, is a core component of acute MTBI care.