Patient Content

Traumatic Brain Injury

Traumatic Brain Injury (TBI) is a disruption in the normal function of the brain that can be caused by a blow, bump or jolt to the head, the head suddenly and violently hitting an object or when an object pierces the skull and enters brain tissue.
  • Nitin Agarwal, MD
  • Rut Thakkar
  • Khoi Than, MD, FAANS

Observing one of the following clinical signs constitutes alteration in the normal brain function:

  • Loss of or decreased consciousness
  • Loss of memory for events before or after the event (amnesia)
  • Focal neurological deficits such as muscle weakness, loss of vision, change in speech
  • Alteration in mental state such as disorientation, slow thinking or difficulty concentrating

Symptoms of a TBI can be mild, moderate, or severe, depending on the extent of damage to the brain. Mild cases may result in a brief change in mental state or consciousness. Severe cases may result in extended periods of unconsciousness, coma, or even death.


According to the CDC, approximately 2.87 million cases of TBI occurred in the U.S. in 2014 with over 837,000 cases occurring amongst children. An estimated 13.5 million individuals live with a disability due to traumatic brain injury in the U.S. alone.

  • Estimated annual direct and indirect TBI costs are $76.5 billion.
  • There are about 288,000 hospitalizations for TBI every year, more than 20 times the number of hospitalizations for spinal cord injury.
  • From 2006, there has been a 53% increase in the total number of TBI related ED visits, hospitalizations and deaths.
  • Among children ages 14 and younger, TBI accounts for an estimated 2,529 deaths, 23,000 hospitalizations, and 837,000 emergency room visits.
  • Each year, 80,000-90,000 people experience the onset of long-term or lifelong disabilities associated with TBI.
  • Males represent 78.8 percent of all reported TBI accidents and females represent 21.2 percent, with higher rates of TBI amongst males (959 per 100,000) than females (811 per 100,000).
  • Sports and recreational activities contribute to about 21 percent of all TBIs among American children and adolescents.
  • The highest rates of TBI are observed in older adults (≥75 years; 2,232 per 100,000 population), very young (0 to 4 years; 1591 per 100,000), and young adults (15 to 24 years; 1081 per 100,000).
  • The mortality rate for TBI is 30 per 100,000, or an estimated 50,000 deaths in the U.S. annually.
  • Deaths from head injuries account for 34 percent of all traumatic deaths. Beginning at age 30, the mortality risk after head injury begins to increase.
  • The leading causes of TBI-related deaths are due to motor vehicle crashes, suicides, and falls.
  • The leading causes of non-fatal TBI in the US occur from falls (35%), motor vehicle-related injuries (17%), and strikes or blows to the head from or against an object (17%), such as sports injuries.


Centers for Disease Control and Prevention (CDC), Traumatic Brain Injury (TBI): Incidence and Distribution, 2014.
Introduction to Brain Injury – Facts and Stats, February 2000.


Symptoms vary greatly depending on the severity of the head injury. They may include any of the following:

  • Vomiting
  • Lethargy
  • Headache
  • Confusion
  • Paralysis
  • Coma
  • Loss of consciousness
  • Dilated pupils
  • Vision changes (blurred vision or seeing double, unable to tolerate bright light, loss of eye movement, blindness)
  • Cerebrospinal fluid (CSF) (clear or blood-tinged) appear from the ears or nose
  • Dizziness and balance concerns
  • Breathing problems
  • Slow pulse
  • Slow breathing rate with an increase in blood pressure
  • Ringing in the ears or changes in hearing
  • Cognitive difficulties
  • Inappropriate emotional responses
  • Speech difficulties (slurred speech, inability to understand and/or articulate words)
  • Difficulty swallowing
  • Body numbness or tingling
  • Droopy eyelid or facial weakness
  • Loss of bowel control or bladder control

If a TBI is suspected, call 911 immediately or take the person to an emergency room.

Types of Injuries

TBIs can cause “mass lesions,” w an area of localized injury such as hematomas and contusions that increase pressure within the brain. Summarized below are different types of sequelae deveoped from TBIs:

Hematoma: A hematoma is a blood clot within the brain or on its surface. Hematomas may occur anywhere within the brain. An epidural hematoma is a collection of blood between the dura mater (the protective covering of the brain) and the inside of the skull. A subdural hematoma is a collection of blood between the dura mater and the arachnoid layer, which sits directly on the surface of the brain.

Contusion: A cerebral contusion is bruising of brain tissue. When examined under a microscope, cerebral contusions are comparable to bruises in other parts of the body. They consist of areas of injured or swollen brain mixed with blood that has leaked from arteries, veins, or capillaries. Most commonly, contusions are at the base of the front parts of the brain, but may occur anywhere.

Intracerebral Hemorrhage: An intracerebral hemorrhage (ICH) describes bleeding within the brain tissue, may be related to other brain injuries, especially contusions. The size and location of the hemorrhage helps determine whether it can be removed surgically.

Subarachnoid Hemorrhage: Subarachnoid hemorrhage (SAH) is caused by bleeding into the subarachnoid space. It appears as diffuse blood spread thinly over the surface of the brain and commonly after TBI. Most cases of SAH associated with head trauma are mild. Hydrocephalus may result from severe traumatic SAH.

Diffuse Injuries: TBIs can produce microscopic changes that do not appear on CT scans and are scattered throughout the brain. This category of injuries, called diffuse brain injury, may occur with or without an associated mass lesion.

Diffuse Axonal Injury: Axonal injury refers to impaired function and gradual loss of axons.These long extensions of nerve cells enable them to communicate with each other. If enough axons are harmed in this way, the ability of nerve cells to communicate with each other and to integrate their function may be lost or greatly impaired, possibly leaving a patient with severe disabilities.

Ischemia: Another type of diffuse injury is ischemia or insufficient blood supply to certain parts of the brain. A decrease in blood supply to very low levels may occur commonly in a significant number of TBI patients. This is crucial since a brain that has just undergone a traumatic injury is especially sensitive to slight reductions in blood flow. Changes in blood pressure during the first few days after head injury can also have an adverse effect.

Skull Fractures: Linear skull fractures or simple breaks or “cracks” in the skull may accompany TBIs.

Possible forces, strong enough to cause a skull fracture may damage the underlying brain. Skull fractures may be alarming, if found on a patient evaluation. Fractures at the base of the skull are problematic since they can cause injury to nerves, arteries, or other structures. If the fracture extends into the sinuses, a leakage of cerebrospinal fluid (CSF) from the nose or ears may occur. Depressed skull fractures, in which part of the bone presses on or into the brain, can also occur.

Testing and Diagnosis

Anyone with signs of moderate or severe TBI should receive medical attention as soon as possible. Because we cannot do much to reverse the initial brain damage caused by trauma, medical providers try to stabilize an individual with TBI and focus on preventing further injury.

First, the cardiac and pulmonary function is assessed. Next, a quick examination of the entire body is performed, followed by a complete neurological examination. The neurological examination includes an assessment utilizing the Glasgow Coma Scale (GCS). In addition to the GCS, also tested is the ability of the pupils to become smaller in bright light. In patients with large mass lesions or with high intracranial pressure (ICP), one or both pupils may be very wide or “blown.” The presence of a wide or dilated pupil on only one side suggests a large mass lesion may be present. Brainstem reflexes including gag and corneal (blink) may also be tested.

Radiological Tests

A computed tomography scan (CT or CAT scan) is the gold standard for the radiological assessment of a TBI patient. A CT scan is easy to perform and an excellent test for detecting the presence of blood and fractures, the most crucial lesions to identify in medical trauma cases. Plain x-rays of the skull are recommended by some as a way to evaluate patients with only mild neurological dysfunction. However, most centers in the U.S. have readily available CT scanning, a more accurate test, rendering the routine use of skull x-rays for TBI patients to decline.

Magnetic resonance imaging (MRI) is not commonly used for acute head injury since it takes longer to perform a MRI than a CT. Because it is difficult to transport an acutely-injured patient from the emergency room to a MRI scanner, the use of MRI is impractical. However, once a patient is stabilized, MRI may demonstrate the existence of lesions that were not detected on the CT scan. This information is generally more useful for determining prognosis than for influencing treatment.



Many patients with moderate or severe head injuries head directly from the emergency room to the operating room. In many cases, surgery is performed to remove a large hematoma or contusion that is significantly compressing the brain or raising the pressure within the skull. After surgery, these patients are under observation in the intensive care unit (ICU).

Other head-injured patients may not head to the operating room immediately, instead are taken from the emergency room to the ICU. Since contusions or hematomas may enlarge over the first hours or days after head injury, immediate surgery is not recommended on these patients until several days after their injury. Delayed hematomas may be discovered when a patient’s neurological exam worsens or when their ICP increases. On other occasions, a routine follow-up CT scanto determine whether a small lesion has changed in size indicates that the hematoma or contusion has enlarged significantly. In these cases, the safest approach is to remove the lesion before it enlarges and causes neurological damage.

During surgery, the hair over the affected part of the head is usually shaved. After the scalp incision, the removed bone is extracted in a single piece or flap, then replaced after surgery unless contaminated. The dura mater is carefully cut to reveal the underlying brain. After any hematoma or contusion is removed, the neurosurgeon ensures the area is not bleeding. He or she then closes the dura, replaces the bone and closes the scalp. If the brain is very swollen, some neurosurgeons may decide not to replace the bone until the swelling decreases, which may take up to several weeks. The neurosurgeon may elect to place an ICP monitor or other types of monitors if these were not already in place. The patient is returned to the ICU for observation and additional care.

Non-Surgical Treatments

At present, medication administered to prevent nerve damage or promote nerve healing after TBI not available. The primary goal in the ICU is to prevent any secondary injury to the brain. The “primary insult” refers to the initial trauma to the brain, whereas the “secondary insult” is any subsequent development that may contribute to neurological injury. For example, an injured brain is especially sensitive and vulnerable to decreases in blood pressure otherwise well tolerated. One way to avoid secondary insults is to attempt normal or slightly elevated blood pressure levels. Likewise, increases in ICP, decreases in blood oxygenation, increases in body temperature, increases in blood glucose and many other disturbances can potentially worsen neurological damage. The major role of ICU management is the prevention of secondary insults in head-injured patients.

Various monitoring devices may assist health care personnel in caring for the patient. Placement of an ICP monitor into the brain can help detect excessive swelling. One commonly used type of ICP monitor is a ventriculostomy, a narrow, flexible, hollow catheter that is passed into the ventricles, or fluid spaces in the center of the brain, to monitor ICP and drain CSF if ICP increases. Another commonly used type of intracranial pressure monitoring device involves placement of a small fiberoptic catheter directly into the brain tissue. Additional catheters may be added to measure brain temperature and brain tissue oxygenation. Placement of an oxygen sensor into the jugular vein can detect how much oxygen the brain is using. This may be related to the degree of brain damage. Many other monitoring techniques currently under investigation to determine whether they can help improve outcome after head injury or provide additional information about caring for TBI patients.


One of the most widely used systems to classify outcome from head injury is the Glasgow Outcome Scale (GOS). Patients with mild head injury (usually defined as GCS score on admission of 13-15) tend to do well. They may experience headaches, dizziness, irritability or similar symptoms, but these gradually improve in most cases.

Patients with moderate head injuries fare less well. Approximately 60 percent will make a positive recovery and an estimated 25 percent left with a moderate degree of disability. Death or a persistent vegetative state will be the outcome in about 7 to 10 percent of cases. The remainder of patients will have a severe degree of disability.

The group comprised of severely head-injured patients has the worst outcomes. Only 25 to 33 percent of these patients have positive outcomes. Moderate disability and severe disability each occur in about a sixth of patients, with moderate disability being slightly more common. About 33 percent of these patients do not survive. The remaining few percent remain persistently vegetative.

The above statistics apply to patients with so-called closed head injuries. For penetrating head injuries, today commonly by handguns, the outcomes follow a different pattern. More than 50 percent of all patients with gunshot wounds to the head, alive upon arrival at a hospital, do not survive due to severe initial injuries. Patients with relatively mild injuries (GCS score of 13-15) tend to do fairly well. Comparatively few patients suffer injuries of intermediate severity (GCS score of 9-12) from gunshot wounds; it is this group that has the most variability in outcomes.

Despite its usefulness, the GOS is not a good tool to measure subtle emotional or cognitive problems. Several months after a severe head injury, patients with a good score on the GOS may have significant neuropsychological disabilities. Tremendous effort is directed to finding better ways to evaluate these problems, improving the quality of prehospital, acute and rehabilitative care, and research to learn more about the effects of head injury and potential treatment options.

Table 1: Glasgow Coma Scale

6Obeys commands
5Localizes stimulusOriented
4Withdraws from stimulusConversant, but confusedEyes open spontaneously
3Flexes armStates recognizable words or phrasesEyes open to voice
2Extends armMakes unintelligible soundsEyes open to painful stimulus
1No responseNo responseRemain closed

Table 2: Glasgow Outcome Scale

Good Recovery (GR)5Minor disabilities, but able to resume normal life
Moderate Disability (MD)4More significant disabilities, but still able to live independently. Can use public transportation, work in an assisted situation, etc.
Severe Disability (SD)3Conscious, but dependent upon others for daily care. Often institutionalized
Persistent Vegetative State (PVS)2Not conscious, though eyes may be open and may “track” movement
Death (D)1Self-explanatory
Teasdale G, Jennett B. Assessment of Coma and Impaired Consciousness. Lancet 1974; 81-84.
Teasdale G, Jennett B. Assessment and Prognosis of Coma After Head Injury. Acta Neurochir 1976; 34:45-55.


Once head-injured patients leave the acute-care hospital, some benefit from a rehabilitation program. Prime candidates for rehabilitation are patients with less severe initial injuries or those that started to show significant improvement.

In some cases, transfer to a rehabilitation hospital or to the rehabilitation service of a large hospital may expedite further recovery. For more severely injured patients or those with slow recovery, constant vigilance is required to prevent the gradual onset of problems with joint mobility, skin integrity, respiratory status, infection and many other physiological functions. Patients with moderate or mild injuries, or severely injured patients who have improved sufficiently, are likely candidates for outpatient therapy.

Most head-injury rehabilitation centers emphasize compensatory strategies to help patients learn to reach the maximum level of function allowed by their impairments. The concept of cognitive retraining, a controversial concept, which presumes that at least some of the brain’s cognitive capacity can be restored by constant repetition of certain simple tasks, is also emphasized at many centers. Head injury rehabilitation centers work with patients’ families to educate them about realistic expectations and best help their injured family member.

General Head Injury Prevention Tips

  • Wear a seatbelt every time you drive or ride in a motor vehicle.
  • Never drive while under the influence of drugs, alcohol or ride as a passenger with anyone who is under the influence.
  • Keep firearms unloaded in a locked cabinet or safe, and store ammunition in a separate, secure location.
  • Remove hazards in the home that may contribute to falls. Secure rugs and loose electrical cords, put away toys, use safety gates and install window guards. Install grab bars and handrails if you are frail or elderly.

Sports and Recreation Head Injury Prevention Tips

  • For specific sports, 100 percent of the time, buy and use helmets or protective headgear approved by the American Society for Testing and Materials (ASTM).
  • Supervise younger children at all times.
  • Do not allow younger children to use sporting equipment or play sports unsuitable for their age.
  • Avoid the use of playgrounds with hard surfaces.
  • Follow all rules and warning signs at water parks, swimming pools and public beaches.
  • Do not dive in water less than 12 feet deep or in above-ground pools. Check the depth – and check for debris in the water before diving.
  • Wear appropriate clothing for the sport.
  • Do not wear any clothing that can interfere with your vision.
  • Do not participate in sports when you are ill or very tired.
  • Obey all traffic signals, and be aware of drivers when cycling or skateboarding.
  • Avoid uneven or unpaved surfaces when cycling, skateboarding or in-line skating.
  • Perform regular safety checks of sports fields, playgrounds and equipment.
  • Discard and replace damaged sporting equipment or protective gear
  • Never slide head-first when stealing a base.

Glossary of Terms

  • Agnosia – failure to recognize familiar objects even though the sensory mechanism is intact
  • Agraphia – the inability to express thoughts in writing
  • Alexia – the inability to read
  • Amnesia – lack of memory about events occurring during a particular period of time
  • Anosmia – loss of the sense of smell
  • Anoxia – a condition in which there is an absence of oxygen supply to an organ’s tissues although there is adequate blood flow to the tissue
  • Aphasia – loss of the ability to express oneself and/or to understand language
  • Arachnoid – middle layer of membranes covering the brain and spinal cord
  • Ataxia – shaky and unsteady movements that result from the brain’s failure to regulate the body’s posture and the strength and direction of movements
  • Axon – the nerve fiber that carries an impulse from the nerve cell to a target and also carries materials from the nerve terminals back to the nerve cell
  • Brain Stem – the stem-like part of the brain that connects to the spinal cord
  • Closed Head Injury – impact to the head from an outside force, without any skull fracture or displacement
  • Concussion – a disruption, usually temporary, of neurological function resulting from a head injury or violent shaking
  • CSF – a clear fluid surrounding the brain and spinal cord
  • Contusion – a bruise; an area in which blood that has leaked out of blood vessels is mixed with brain tissue
  • Coup-Contrecoup Injury – contusions that are both at the site of the impact and on the complete opposite side of the brain
  • Depressed skull fracture – a break in the bones of the head in which some bone is pushed inward, possibly pushing on or pressing into the brain
  • Diplopia – a condition in which a single object appears as two objects; also called double vision
  • Dura mater – the outermost, toughest and most fibrous of the three membranes (meninges) covering the brain and the spinal cord
  • Dysarthria – speech that is characteristically slurred, slow and difficult to understand
  • Edema – collection of fluid in the tissue causing swelling
  • Epidural – located on or outside the dura mater, the outermost, toughest and most fibrous of the three membranes (meninges) covering the brain
  • Hemiplegia – paralysis of one side of the body as a result of injury to neurons carrying signals to muscles from the motor areas of the brain or spinal cord
  • Hemiparesis – weakness, paralysis or loss of movement on one side of the body
  • Hemianopsia – loss of part of one’s visual field in one or both eyes
  • Hydrocephalus – a condition in which excess CSF builds up within the ventricles (fluid-containing cavities) of the brain and may cause increased pressure within the head
  • Hypoxia – a condition in which there is a decrease of oxygen to the tissue despite adequate blood flow to the tissue
  • Intraparenchymal – inside the parenchyma of the brain
  • Ischemia – a reduction of blood flow that is thought to be a major cause of secondary injury to the brain or spinal cord after trauma
  • Locked-in Syndrome – a rare neurological condition in which a person cannot physically move any part of the body except the eyes
  • Open head injury – trauma to the brain resulting in loss of consciousness due to the penetration of the brain by a foreign object, such as a bullet
  • Subarachnoid hemorrhage – Blood in, or bleeding into, the space under the arachnoid membrane, most commonly from trauma or from rupture of an aneurysm
  • Subcortical – the region beneath the cerebral cortex
  • Subdural – the area beneath the dura covering the brain and spinal cord
  • Vasospasm – spasm of blood vessels which decreases their diameter
  • Ventricles (brain) – four natural cavities in the brain which are filled with CSF

Traumatic Brain Injury Resources

Author Information

Edited on 2/3/2020 by Nitin Agarwal, MD, Rut Thakkar, Khoi Than, MD, FAANS

Note from AANS

The AANS does not endorse any treatments, procedures, products or physicians referenced in these patient fact sheets. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific neurosurgical advice or assistance should consult his or her neurosurgeon, or locate one in your area through the AANS’ Find a Board-certified Neurosurgeon online tool.