What are the Different Types of Brain Injury?

Traumatic brain injury, or TBI, is a common medical condition. An estimated 2.8 million people are diagnosed with a TBI in the United States each year. According to the US Centers for Disease Control and Prevention (CDC), in the year 2020, more than 64,000 Americans died as a result of TBI-related injuries, which translates to an estimates 176 TBI-related deaths each day of that year. Approximately 282,000 people are hospitalized as a result of complications related to brain injuries, and roughly 2.5 million, or nearly 90 percent of TBI patients are treated and released from an emergency room each year.

If you or someone you love has sustained an injury to the head, you may be wondering if a TBI has occurred as a result of the injury. The following is an overview of traumatic brain injury, including what TBI is, the different types of TBI, how TBI is diagnosed, the effects of brain injuries, and more.

Traumatic Brain Injury Defined

A traumatic brain injury (TBI) is an injury that impacts the function of the brain. A TBI can occur when a sudden, external, physical impact damages the brain. The injury can be caused by a blow, bump, or jolt to the head, or it can occur as a result of a penetrating injury, such as a gunshot wound to the head.

TBI is one of the most common causes of disability and death in American adults each year. Children and infants can be affected by this condition, too. The term TBI is broad in that it is used to describe a wide range of injuries that negatively impact the brain. The damage can be focal, meaning that only one part of the brain is impacted, or it can be diffuse, meaning that more than one part of the brain is affected. The severity of a TBI can range from a mild concussion to a severe injury that results in long-term or permanent damages, or even death.

An Overview of Brain Injuries: Description, Diagnosis, Effects, and More

Brain injuries can occur in one of two ways:

  • Closed injury. A closed brain injury is the result of a non-penetrating injury to the brain, and the injury does not cause the skull to break. This type of injury occurs when there is rapid movement to the head in a forward or backward manner, and that movement caused the brain to shake within the skull. This shaking causes bruising and/or tearing of the blood vessels and brain tissues. Some of the most common causes of closed brain injuries include:
    • Motor vehicle accidents
    • Slips and falls
    • Sports-related incidents
    • Assault

Shaken Baby Syndrome is the most common cause of closed brain injury in infants.

  • Penetrating injury. A penetrating brain injury, or an open head injury, occurs when there is an injury that causes a break in the skull. A bullet wound to the head, a broken piece of skull, or other sharp or blunt objects, such as fence posts or metal poles, are some examples of injuries that can result in a penetrating brain injury.

In addition to closed and open brain injuries, TBIs can also be classified as one of the following:

  • A mild TBI or concussion. A mild TBI or a concussion occurs when there is a bump, blow, or jolt to the head, or when a patient sustains an impact to the body that causes the head and the brain to rapidly move back and forth in the skull. This sudden movement can cause the brain to bounce or twist, can cause chemical alterations in the brain, or can cause the brain cells to stretch and become damaged. Mild TBIs and concussions are the most common cause of TBI in the United States. Despite the term “mild”, this form of TBI should not be considered mild; rather, mild TBIs and concussions are serious medical conditions that require immediate medical attention.
  • Moderate or Severe TBI. A moderate or severe brain injury occurs when an individual sustains a bump, blow, or jolt to the heat, or when a person experiences a penetrating injury (penetrating brain injury), such as a gunshot wound, to the head. Each year, thousands of deaths in the United States are linked to moderate and severe TBIs. In some cases, patients can die as a result of moderate or severe TBI. For those who survive, long-term or permanent health issues can occur and impact every aspect of a person’s life. The health complications that are associated with moderate and severe TBIs have been likened to the effects of chronic diseases.

What are the Symptoms of a TBI?

The symptoms that are associated with a TBI vary and are wide ranging. The type of injury and the extent of the damage will impact the symptoms that a patient will experience. That said, if you or someone you love have sustained an injury to the head, the following are some symptoms to be on the lookout for that may indicate injury to the brain.

  • Confusion
  • Coma
  • Nausea and vomiting
  • Lethargy
  • Paralysis
  • Loss of consciousness
  • Dilated pupils in one or both eyes
  • Changes in vision, such as blurred vision, seeing double, inability to tolerate bright lights, inability to move the eyes, and even blindness
  • Dizziness and loss of balance
  • Breathing issues
  • Clear or blood-tinged fluid dripping from the nose and/or ears (this is cerebrospinal fluid, or CSF)
  • Slowed pulse
  • Slowed breathing rate and increased blood pressure
  • Ringing in the ears (tinnitus) or loss of hearing in one or both ears
  • Cognitive impairments, such as difficulty remembering information
  • Changes in speech, such as slurred speech, and/or an inability to articulate or understand words
  • Mood swings
  • Irritability
  • Increased desired to sleep
  • Inability to fall asleep or stay asleep
  • Depression and/or anxiety
  • Difficulty swallowing
  • Numbness or tingling in the body; in one or both arms, hands, legs, feet, etc.
  • Facial weakness
  • Droopy eyelid
  • Loss of bladder and/or bowel control

If a traumatic brain injury is suspected, emergency medical care should be sought immediately. Either dial 911 or bring the person to an emergency room.

What Kind of Injuries are Associated with TBIs

Traumatic brain injuries, no matter the type, the cause, or the severity, can cause mass lesions in the brain. The lesions can be localized to the area of the injury, such as hematomas and contusions that increase pressure on the brain. The following is an overview of the most common injuries that are associated with TBIs.

  • Hematoma. A hematoma is a blood clot that develops either inside the brain or on the surface of the brain. They can develop anywhere in or on the brain. Epidural hematomas can occur, as well. An epidural hematoma occurs when blood collects between the brain’s protective covering (the dura mater) and the interior of the skull. A subdural hematoma occurs when blood collects between the dura mater and the arachnoid layer, which is located on the brain’s surface.
  • Cerebral contusion. A cerebral contusion refers to bruising of the brain tissue. They are similar to bruises that occur on other parts of the body, such as the arms or the legs. Cerebral contusions are comprised of areas of the brain that are either swollen or injured, and that are mixed with blood that has leaked out of the capillaries, the veins, or the arteries. Cerebral contusions commonly occur either on the front parts of the brain, along the base; however, they can occur on any part of the brain.
  • Subarachnoid hemorrhage (SAH). An SAH occurs when there is bleeding in the subarachnoid space of the brain. An SAH presents as blood vessels that are diffused in a thin layer over the surface of the brain following a TBI. The majority of SAH cases are occur following trauma to the head are mild in nature.
  • Intracerebral hemorrhage (ICH). An ICH is defined as bleeding that occurs within the brain tissue. This bleeding can be related to other types of injuries to the brain, particularly contusions. Depending on the size and the location of an ICH, there is a chance that it could be surgically removed.
  • Diffuse injuries. A TBI can cause tiny, microscopic alterations to the brain that are usually scattered throughout the brain. The alterations can be so small that they will not appear on CT imaging. This class of injuries, known as “diffuse brain injury”, can occur either with or without mass lesions.
  • Ischemia. An ischemia is a diffuse injury. It occurs when certain parts of the brain don’t receive sufficient amounts of blood. Ischemia is a common injury among those who sustain TBIs, and it is considered serious, as further injury can occur.
  • Diffuse axonal injuries. An axonal injury describes an impairment in function and a gradual decline and eventual loss of axons. Axons are long extensions of nerve cells that communicate with one another. When the axons are damaged, the nerve cells will no longer be able to communicate with each other, and as a result, they will not be able to integrate their appropriate function, which can result in either impaired or completely lost functioning. Patients who experience diffuse axonal injuries may experience severe long-term or permanent disabilities.
  • Fractures to the skull. Cracks, breaks, or linear fractures to the skull can also occur as a result of traumatic brain injuries. When the impact sustained to the brain is strong enough to fracture the skull, underlying parts of the brain can be damaged. Skull fractures can be quite concerning. If they occur at the base of the skull, this is particularly problematic, as these fractures can injure the nerves, arteries, and other vital parts of the brain. Should a fracture to the skull extend to the sinuses, cerebrospinal fluid (CSF) can lead from the nose and/or ears. Portions of the skull bone can press on the brain, or a depressed skull fracture, can also occur in TBI patients.

How is TBI Diagnosed?

If you or a loved one has sustained an injury to the head, whether or not symptoms are exhibited (but especially if they are exhibited), immediate medical attention is essential. Unfortunately, there isn’t much that can be done to reverse the initial effects that the brain experiences as a result of trauma; however, healthcare professionals can attempt to stabilize a TBI patient and concentrate on preventing additional and even more extensive damage from occurring.

Medical providers will first assess the patient’s cardiac and pulmonary function. They will then examine the patient’s entire body. Finally, a comprehensive neurological examination will be performed. The Glasgow Coma Scale (GCS) will be used during this examination, and the patient’s pupils will be assessed to determine whether or not they react to light (become smaller and larger). TBI patients who develop large mass lesions on the brain, or whose intracranial pressure (ICP) is high, either one or both of their pupils will appear “blown”, or will remain very wide or dilated. If only one pupil is dilated, this indicates that a mass lesion may have occurred. The patient’s ability to blink (known as “brainstorm reflexes”) can also be assessed.

Several diagnostic tests can also be performed on a suspected TBI patient to not only confirm the diagnosis, but to confirm the severity of the diagnosis. The following are some of the tests that can be performed:

  • Computed tomography scan. A computed tomography (CT or “CAT”) scan is considered the gold-star standard in radiological testing for brain injury patients. CT scans can detect the presence of the two most critical impacts that need to be identified in TBI patients: blood and fractures. CT scans involve a combination of a series of X-ray images, which are taken from different angles around the head. Computer processing is used to create cross-sectional images of the brain. CT scans offer more detailed information than traditional X-rays.
  • Magnetic resonance imaging. Magnetic resonance imaging (MRI) can also be used to assess the impact of a TBI. While it isn’t commonly used, as CT scans are faster, an MRI can be used to further assess a patient’s brain following a TBI once a patient has been stabilized to determine if lesions are present that the CT scan may not have detected. Though an MRI takes longer, the information the images provide can be more useful for developing a more precise prognosis and treatment course.

What are the Treatments for TBI?

There are several treatment options available for TBI patients. The type of treatment a patient will require depends on several factors, including the severity of the damage and the symptoms that the patient is exhibiting. Treatments fall under two categories:


Patients who sustain moderate or severer TBIs often require immediate surgical treatment. Surgery can be performed to remove large contusions or hematomas that are significantly compressing the brain, or that are increasing the level of pressure in the skull. Following surgery, patients will be cared for in the intensive care unit (ICU), where they will remain under constant observation.

In other cases of brain injuries, patients may not require immediate surgery; rather, they are brought to the ICU. Because hematomas and contusions can grow larger within the first few hours or days following a brain injury, immediate surgical intervention should be avoided until several days post-injury. Delayed onset hematomas and contusions can be found if a patient’s neurological exams worsen, or if their ICP increases. These injuries can also be discovered during routine follow-up CT scans.

Non-surgical interventions

Presently, medications that can stop nerve damage from occurring or that can prompt the healing of the nerves within the brain following a TBI are not available. As such, non-surgical interventions include constant and close observation. A patient’s blood pressure will be assessed, as well his or her blood oxygen levels, body temperature, and blood glucose levels. Changes in any of these elements can indicate worsening neurological damage. Devices can also be used to monitor the brain. For example, devices that can detect excessive swelling within the skull can be used. Intracranial pressure monitoring devices can also be used.