Causes and Symptoms

Causes and Symptoms

Traumatic Brain Injury (TBI) occurs more often than you would think, and there are any number of scenarios that can cause it. Some of the more obvious include severe auto accidents. For instance, a passenger may be thrown through the windshield and hit their head on the pavement. Another common example could be an elderly person slipping in the shower and banging their head on the way down. However, we tend to forget that a football player can sustain a brain injury during a tackle that is just as devastating as one caused by a car crash. Here, we have outlined the key conditions responsible for TBI and the circumstances that produce them.

Since there are so many variations of TBI, it can be expected that each diagnosis is linked to a unique set of symptoms. But, obviously a mild brain injury is not going to exhibit all of the side effects that a severe brain injury would, and some of those linked to severe TBI would be of much more serious nature. This list is a good point of reference to help you determine the severity of a head injury.

Featured Topics

  • Causes
  • Mild TBI Symptoms
  • Severe TBI Symptoms


It is hard to come up with an exact number of people suffering from Traumatic Brain Injury (TBI), but there are many more than you would think. According to records maintained by the United States Centers for Disease Control and Prevention, there are close to 1.5 million new victims of TBI every year. 50,000 people die as a result of TBI on an annual basis, and 85,000 are diagnosed with long-term disabilities. Only TBI patients who are treated in the hospital are included in this pool, but any who were cared for in the ER or doctor’s office are omitted.

There are a variety of causes of TBI, but the three most prevalent are auto accidents, gunshot wounds, and falls. Nine out of ten shooting victims are fatally wounded. Teens and seniors are the two groups most prone to TBI. Since there isn’t a cure for TBI, educating each other about how to prevent it is the best solution. The following scenarios are notorious for leading to TBI:Open head injury

  • Commonly results from bullet penetration
  • Primarily focal damage
  • Intrusion of the skull
  • Impact may be just as severe as closed head injury

Closed head injury

  • Caused by falls, car crashes, etc.
  • Focal damage and widespread harm to axons
  • Effects are normally diffuse
  • No skull infiltration

Diffuse axonal injury (Deceleration injury) Everyone knows that our brains our housed inside the skull and that the skull is very hard and rigid, but not everyone is aware that the human brain has the texture of Jell-O. As a person’s head moves through space (accelerates) and suddenly collides with a motionless object (decelerates), the brain’s momentum forces it to shift inside the skull. The brain travels at a different speed compared to the skull because it has a lower density. Various sections of the brain do not move at the same rate because some are heavier than others. This difference in movement between the skull and brain when a person’s head strikes an object is what causes diffuse axonal shearing, bruising, swelling, and ultimately, brain damage. Diffuse axonal shearing occurs when the brain is rattled back and forth, compressing and stretching as it collides with the victim’s skull. The elongated, delicate axons of the neurons, which are the single nerve cells found in the brain and spinal cord, are also compacted and expanded. If the blow is powerful enough, axons may be stretched until they tear, which is known as axonal shearing. This causes the neuron to die. In the case of a severe brain injury, substantial axonal shearing and neuron death occurs. Chemical/Toxic

  • Also called metabolic disorders
  • Dangerous chemicals harm neurons
  • Harmful chemicals or toxins may be found in pesticides, solvents, carbon monoxide, lead, etc.

Hypoxia (Oxygen shortage)

  • If blood is lacking oxygen, permanent brain damage can happen due to anoxia (no oxygen) or hypoxia (reduced oxygen)
  • Only requires a few minutes to take effect
  • May be triggered by heart attacks, respiratory failure, low blood pressure, or an environment with oxygen saturation well below average
  • Resulting brain damage can cause harsh cognitive and memory problems


  • Cancerous tumors can grow directly on or over the brain
  • By occupying the crevices of the brain, tumors cause damage
  • Large tumors can do damage by putting pressure on surrounding brain tissue
  • Surgery to remove brain tumors can be risky and also result in brain damage


  • The brain and its membranes are breeding grounds for infections if its unique blood-brain protective shield is invaded
  • Viruses and bacteria have the potential to cause deadly diseases of the brain (encephalitis) and meninges (meningitis)


  • Causes cells to die in area of the brain where blockage of blood occurred
  • If bleeding occurs inside (hemorrhage) or around the brain (hematoma) as a result of a torn artery or vein, stifled blood flow and injury to brain tissue from contact with the blood will cause brain damage

Mild Traumatic Brain Injury Symptoms

A mild Traumatic Brain Injury (TBI) occurs when the victim undergoes a period of unconsciousness and/or bewilderment that lasts less than a half hour due to the forceful motion of the head colliding with another object. MRI and CAT scans are normally used to diagnose problems associated with the injury, but they cannot detect side effects like headaches, problems with processing information, memory loss, short attention span, mood swings, and irritation. As a result, these injuries are often ignored my medical personnel. Although this is the least severe form of TBI, the impact that it has on the victim and their family can be overwhelming.

Mild TBI is also referred to as:

  • Concussion
  • Minor head trauma
  • Minor TBI
  • Minor brain injury
  • Minor head injury

Quick facts

  • The most common type of TBI is mild.
  • Mild TBI often goes unnoticed at the onset of the injury.
  • 15 percent of mild TBI victims experience symptoms for at least one year following the injury.
  • Post concussive syndrome refers to the symptoms a victim feels in the aftermath of an injury.

Regular Symptoms of mild TBI

  • Tiredness
  • Headache
  • Impaired eyesight
  • Inability to remember things
  • Poor attention span
  • Inability to sleep through the night
  • Vertigo
  • Ill-tempered
  • Depression
  • Convulsions

Additional symptoms related to mild TBI

  • Queasiness
  • Loss of scent
  • Sensitivity to light and loud noises
  • Mood swings
  • Disorientation
  • Delayed comprehension

It may take days or even weeks for these symptoms to appear after the injury occurs. These symptoms are often so discreet that doctors, friends, family, and even the victims may not recognize them. A victim of mild TBI will usually appear and move as if nothing is wrong despite the fact that they are not feeling or thinking normally. This is the reason why mild TBI is easily misdiagnosed. Those that have close personal relationships with the victim often notice there is something wrong before the victim does. Constant aggravation while working or performing household chores may finally convince the victim that they should seek medical assistance.

Severe Traumatic Brain Injury Symptoms

A Traumatic Brain Injury (TBI) varies anywhere from mild to severe. Victims of TBI suffer from permanent neurobiological damage that can result in disability that spans the remainder of their lifetime. Moderate TBI means the victim was unconscious between 20 minutes and six hours and has a rating of nine to 12 on the Glasgow Coma Scale. Meanwhile, a victim of severe TBI must have been unconscious for more than six hours rate from three to eight on the Glasgow Coma Scale.

The effect that a moderate to severe brain injury has on its victim is reliant upon the:

  • Seriousness of the original injury.
  • Speed of physiological recuperation.
  • Mental or motor functions impacted.
  • Effects that dysfunction has on the victim.
  • Available means to assist with recovery.
  • Skills that remain unaffected by TBI.

Depending on the level of severity, moderate to severe TBI can result in the following sensatory, physical, and psychological symptoms:

Cognitive behaviors

  • Difficulty focusing and paying attention
  • Memory loss
  • Delayed information analysis
  • Perplexity
  • Redundancy without realizing
  • Carelessness
  • Problems interpreting spoken word
  • Difficulty making decisions

Speech and language

  • Inability to comprehend speech (receptive aphasia)
  • Problems with speech and articulation (expressive aphasia)
  • Garbled speech
  • Uneven speech tempo
  • Literacy problems


  • Inability to decipher touch (e.g., temperature), movement, and limb position


  • Difficulty drawing conclusions by piecing together data collected through the senses


  • Limited or complete loss of eyesight
  • Deterioration of eye muscles and double vision (diplopia)
  • Cloudy vision
  • Problems with depth perception
  • Uncontrollable eye movements (nystagmus)
  • Extreme sensitivity to light (photophobia)


  • Ailing or total hearing loss
  • Ringing of the ears (tinnitus)
  • Sensitivity to noise


  • Inferior sense or total loss of smell (anosmia)


  • Inferior sense or total loss of taste


  • Spasms related to epilepsy that can interrupt the victim’s state of consciousness and sensory and motor skills


  • Paralysis
  • Continual pain
  • Loss of bowel and bladder control
  • Difficulty sleeping
  • Low energy reserves
  • Loss of appetite
  • Problems with body’s self-regulating temperature mechanism
  • Irregular menstrual cycle


  • Increased dependency on others
  • Difficulty showing feelings and emotion
  • Laziness
  • Hypersensitivity
  • Anger
  • Dejection
  • Impulsive choices
  • Oblivious to various situations