Head Injury – Causes, Signs and symptoms

Head Injury

Also called: Brain Trauma, Brain Injury, Head Trauma


Head injuries are a common type of injury. They can be either blunt or penetrating types of trauma. Head injuries can be external, internal or both. External head injuries often look severe because they may bleed heavily. However, internal head injuries (also known as traumatic brain injuries) are typically more serious than external head injuries because they can affect the way the brain functions.

Types of internal head injury include:

  • Concussion. A loss of consciousness.
  • Skull fracture. A break or crack in the skull.
  • Contusion. Bruising of the brain.
  • Diffuse axonal injury. Damage to the nerve cells in the brain.
  • Hematoma. Bleeding or blood clot in the brain.

Head injuries are most often caused by accidents involving vehicles. However, many of these injuries can be prevented by taking proper safety precautions, such as wearing a seatbelt in an automobile or using protective helmets and face shields on a motorcycle or bicycle. Other causes of head injuries include falls, gun-shot wounds and injuries sustained while playing contact sports.

The signs and symptoms of head injury range from external bleeding and bruising to paralysis and changes in personality. The most common symptoms of a head injury include headache, short-term confusion, dizziness or lightheadedness, nausea and blurred vision, among many other possible symptoms.

These symptoms can go away after a short period of time, or they can become progressively worse. People who have a head injury and experience any of the following severe symptoms should contact emergency services immediately:

  • Increasing sleepiness or confusion
  • Persistent vomiting
  • Paralysis of one or more limbs
  • Inability to speak coherently
  • Lack of coordination
  • Clear fluid (cerebrospinal fluid) draining from nose or mouth

Physicians use imaging tests, such as x-rays, computed axial tomography (CAT) scans and magnetic resonance imaging (MRI), to assess the extent of a head injury. These can help physicians identify any damage that may have been sustained to the skull or brain.

Most people who have moderate to severe head injuries require some type of rehabilitation. Rehabilitation is designed to enable the patient to return to daily activities as soon as possible. It may involve help with the recovery of speech and movement. Many rehabilitation programs also aid patients with any psychiatric problems that may have developed as a result of their injury.

About head injury

Head injuries occur when the head is directly injured by a sharp or blunt object. They can also result from the sudden acceleration or deceleration of the head, which can cause the brain to come into contact with the skull.

Head injuries are sometimes mild and have only minor repercussions for the brain. However, severe head injuries can seriously affect the brain and cause problems with speech, movement and behavior. According to the National Center for Injury Prevention and Control (NCIPC), roughly 1.4 million people sustain an internal head injury (traumatic brain injury) and 50,000 people die as a result of these injuries each year in the United States. Moreover, deaths related to head injuries account for one-third of all injury deaths, according to the NCIPC.

The brain is protected by the thick bones of the skull and a layer of tissue called the meninges that surrounds and cushions the brain and spinal cord. If the head is hit with sufficient force, the skull, meninges or brain can be damaged. Severe brain injury can occur when the brain shifts inside the skull, or when bleeding or bruising inside the skull cause pressure to build against the brain. This can disrupt the normal function of the brain and cause symptoms that range in severity from headache to permanent loss of brain function (brain death).

Following a severe head injury, the patient can become unconscious, such as during a stupor (state of impaired consciousness) or coma. In some cases, the patient may “wake up” and regain normal cognitive function. However, if the injury is too severe, the damage may be permanent and the patient may never regain full consciousness.

Scientific evidence indicates that even cases of apparently mild head injury can cause long-term illnesses later in life. This is especially likely if several head injuries are sustained over a period of time. Illnesses that can be triggered by head injuries, or that may occur earlier in people with a history of head injuries, include:

  • Dementia. People who receive repeated blows to the head over a sustained period of time (e.g. professional boxers) can develop a form of dementia called dementia pugilistica. This type of dementia often occurs simultaneously with Parkinson’s disease. Another type of dementia, called post-traumatic dementia, can develop in people who experienced a head injury that resulted in a coma.

  • Hypothyroidism. Brain injuries that damage the pituitary or thyroid glands can cause an imbalance of hormones in the body. Hypothyroidism (also called an underactive thyroid) can cause fatigue and weight gain, and usually requires treatment with synthetic hormones.

  • Epilepsy. People who have sustained a head injury are up to two times more likely to develop epilepsy. Seizures immediately following the injury are common and generally not considered to be epileptic in origin. However, some people experience recurrent seizures as a result of the damage sustained to the brain from the injury.

Medical scientists are also finding increasing evidence indicating a link between head injuries and Alzheimer’s disease and Parkinson’s disease.

Head injury is more common in the following populations:

  • Males aged 15 to 24
  • Elderly people over age 75
  • Children under age 6

Types and differences of head injury

Superficially, head injuries can be divided into two categories: those that damage the exterior of the head and those that damage the interior of the head. Head injuries often fall into both categories and severe internal damage can sometimes be masked by apparently mild external injuries. Alternatively, external head injuries can appear severe even when no internal injury has occurred. This is partially because the numerous blood vessels under the skin of the scalp can cause heavy bleeding, even when injuries are minor. The lump that sometimes appears after a head injury is caused by the blood vessels in the scalp leaking blood or fluid under the skin. These lumps usually disappear after a period of days or weeks as the body gradually resorbs the blood collection.

Internal head injuries are injuries that have damaged the brain. This type of injury is sometimes called traumatic brain injury and can range in severity from mild concussion to severe brain damage. Some types of traumatic brain injuries include:

  • Concussion. Technically defined as a loss of consciousness following a blow to the head. Most people view a concussion as any head injury that results in dizziness, lightheadedness or temporary confusion, with or without loss of consciousness. It is caused by the brain shifting and coming into contact with the hard and rigid bone of the skull. Concussions can be mild or severe and are the most common type of head injury, especially among children.

  • Skull fractures. A crack or break in the hard bone of the skull. This can happen after a heavy blow to the head. Young children may be more susceptible to skull fractures because the skull may not be completely formed. Skull fractures may be simple and linear, which means that the break runs in a line with no splintering or break in the skin. They can also be compound or depressed. Compound skull fractures may involve splintering of the bone and/or tearing of the skin. Depressed skull fractures are breaks that put pressure on or splinter into the brain. Compound and depressed fractures can cause blood clots (hematoma) and other types of brain damage.

  • Contusion. Bruising of brain tissue. Contusions can occur when a depressed skull fracture puts pressure on the brain, causing the blood vessels in the brain to burst and the brain tissue to swell. Contusions can also occur when the brain moves rapidly within the skull (called contrecoup). This sometimes happens during a car accident or as a result of shaken baby syndrome. Some severe contusions may require surgical removal or repair.

  • Diffuse axonal injury. Damage to nerve cells (neurons) throughout the brain. This type of brain injury can occur after the head has been severely shaken or rotated sharply. As the brain moves against the skull, the nerve tissue in the brain is damaged and the neurons are unable to communicate with each other effectively. Diffuse axonal injury often results in coma or permanent brain damage.

  • Hematoma. Bleeding from a major blood vessel in the head. There are three layers of meningesdura mater (outer lining), arachnoid (middle lining) and pia mater (the inner lining) – which line and protect the brain and spinal cord. The meninges contain cerebrospinal fluid and numerous blood vessels. Epidural hematoma occurs when there is bleeding between the skull and the dura. Subdural hematoma occurs when there is bleeding between the dura and the arachnoid membrane. Intracerebral hematoma occurs when there is bleeding within the brain.

  • Anoxia. Lack of oxygen to the brain. This can be caused by a stroke (where the brain is deprived of oxygen-carrying blood) or an event, such as drowning or cardiac arrest, when the brain is deprived of oxygen despite adequate blood-flow. Brain cells that are not supplied with oxygen can die within minutes. Severe instances of anoxia can cause coma or brain death.

Another common categorization of head injuries is whether the injury is closed or open. A closed head injury occurs when the head is hit by a blunt object, for example. This type of injury can be mild or severe. Concussion is a type of closed head injury. An open head injury occurs when an object penetrates the skull and enters the brain tissue or leaves an opening in the skull that exposes the intracranial contents to the outside environment. These types of injuries are almost always severe and happen most frequently as a result of car accidents.

Potential causes of head injury

There are various causes of head injuries, most of which can result in both external and internal damage. Roughly 50 percent of internal head injuries (traumatic brain injuries) are caused by accidents that involve automobiles, motorcycles, bicycles or pedestrians, according to the National Institute of Neurological Disorders and Stroke (NINDS).

Head injuries sustained during an automobile-related accident can be closed (e.g., if the head hits the steering wheel or other hard object) or open (e.g., if a piece of debris penetrates the skull and enters the brain). People who fail to take proper safety precautions (e.g. wearing a seatbelt in a car, wearing a helmet when riding a bicycle or motorcycle) have a greater risk of head injury than those who take such precautions. Transportation-related accidents (those that involve cars, motorcycles, bikes and pedestrians) are the most common cause of brain injury in people under the age of 75, according to NINDS.

Other potential causes of head injuries include:

  • Falls and other accidents. Falls are the leading cause of hospitalization due to brain injury among people older than 65 years, according to the U.S. Centers for Disease Control and Prevention (CDC). Children are also susceptible to falls and accidents around the house. Most childhood falls result in external injuries rather than internal injuries, which may appear more serious but are often less severe than internal injuries.
  • Contact sports. The CDC estimates that 300,000 brain injuries, typically concussions, result from sports-related activities each year. People who play contact sports, such as football, hockey and boxing, are most at risk. There is evidence that people who play contact sports are also at risk for a potentially fatal condition called second impact syndrome. This rare condition occurs when the brain sustains a series of minor blows within a short space of time.
  • Violence-related injuries. Twenty percent of head injuries are caused by violence, including domestic abuse, child abuse and gun-related crime, according to NINDS. Although firearms cause only 10 percent of brain injuries, they cause 44 percent of brain injury-related death, according to the CDC. The majority of gun-related brain injuries occur as a result of suicide attempts.
  • Alcohol abuse. Intoxication increases the likelihood of engaging in risky behavior, which, in turn, increases the risk of sustaining a head injury. According to NINDS, half of all head injuries involve alcohol use in some way.

Signs and symptoms of head injury

The signs and symptoms of a head injury vary depending on the severity of the injury and whether the injury is internal or external. External symptoms may appear worse because they often involve a great deal of blood loss, but are typically less severe than internal symptoms. In addition, external head injuries may indicate internal injuries. External symptoms may include:

  • Bleeding from the head
  • Lump or welt at the site of the injury
  • Pain
  • Bruising

Sometimes it is obvious that a person has sustained an internal injury. For instance, if someone experiences a loss of consciousness following a head injury, no matter how brief, it is an indication that the brain has been affected in some way. In many cases, internal injuries can be mild and the signs and symptoms are temporary. The signs and symptoms of internal head injuries may include:

  • Headache
  • Short-term confusion
  • Dizziness or lightheadedness
  • Nausea
  • Feelings of irritability or lethargy
  • Blurred vision
  • Ringing in the ears (tinnitus)
  • Memory loss
  • Bad taste in mouth
  • Fatigue

In some cases, the brain may be injured more severely. However, the true extent of brain injury may not be apparent for days or sometimes weeks after the head injury. Signs and symptoms of severe or traumatic brain injury include:

  • Headache that gets worse over time or does not go away
  • Sustained nausea or vomiting
  • Seizures
  • Inability to wake from sleep
  • Unusual eye movements
  • Dilation of one or both pupils of the eyes
  • Slurred speech
  • Weakness or numbness in the extremities
  • Loss of coordination
  • Cerebrospinal fluid draining from the nose or mouth

Most symptoms of head injury, both external and internal, are temporary. However, in cases of severe head trauma, complications can arise that may be permanent. Some people may experience the following permanent symptoms after severe head trauma:

  • Personality changes
  • Problems with speech and language
  • Seizure disorder (epilepsy)
  • Loss of one or more of the senses
  • Paralysis
  • Coma

People who sustain or live with someone who has sustained a head injury should remain vigilant for the signs and symptoms of severe internal injury. If any of the symptoms of severe head injury occur, emergency services (911) should be contacted.

Diagnosis methods for head injury

Diagnosis of a head injury can be made by a physician or paramedics, depending on the circumstances of the injury. In some cases, the evidence of a head injury is obvious – the person is unconscious and has clear signs of external injuries, for example.

If paramedics are called to the scene of an accident of a potential head injury, they will assess the extent of the injury using a standardized scale called the Glasgow Coma Scale. This is a three-part, 15-point physical assessment that tests the patient’s ability to open the eyes, speak coherently and move the arms and legs. A score of three to eight on the scale means that the patient has sustained a severe head injury, nine to 12 indicates a moderate head injury and 13 to 15 means that the head injury is mild. Depending on the severity of the injury, the patient will be transported to a hospital where further tests will be performed.

In cases of apparently mild head injuries, a person can seek medical attention, during which a physical examination and a medical history will be conducted. The patient will be asked questions related to the circumstances of the head injury and on the nature of their symptoms. It is important that the patient discuss any and all symptoms that could be related to the head injury. The possible symptoms include headaches, mood swings, irritability, vomiting or disturbances in vision or other senses.

A physician may recommend the following tests to assess the extent of the head injury:

  • X-ray. A painless test in which an image is created of part of the body by using low doses of electromagnetic radiation that are reflected on film paper or fluorescent screens. An x-ray is effective at diagnosing skull fractures, although it is less effective at diagnosing specific problems within the brain. For this purpose, a computed axial tomography (CAT) scan or magnetic resonance imaging (MRI) may be used.

  • CAT scan. A noninvasive or minimally invasive test that uses a rotating x-ray device to create three-dimensional, cross-sectional images (or slices) of different body parts, including the brain and skull. CAT scans can be used to diagnose numerous conditions and complications which may arise from a head injury, such as blood clots, hematomas and skull fractures. They can also be used to guide a biopsy.

  • MRI. A noninvasive procedure that uses powerful magnets and radio waves to produce clear, cross-sectional or three-dimensional images of many bodily tissues. MRIs are particularly useful in cases of head injuries because they can assess how the brain is functioning. This type of MRI is called a functional MRI (fMRI). During an fMRI, the patient may be asked to perform a task while the machine scans the brain and records brain activity. This information can then be used to determine which parts of the brain may be damaged.

Treatment options for head injury

Treatment options for a head injury depend on the severity of the injury. External head injuries may require first aid only. Even minor external head injuries can bleed profusely, so it is important to stop the bleeding as soon as possible. Firm yet gentle pressure should be applied to the wound with a clean cloth, tissue or bandage. Using a finger or hand, pressure should be continuously placed on the injury for 10 to 15 minutes. The cloth or bandage should not be lifted during this time because it will damage the blood clot that is forming in the wound and cause the bleeding to begin again. In cases of severe external head injuries, the patient should be taken to an emergency room for immediate medical assistance.

Internal head injuries may require further treatment. If the head injury is an open or penetrating injury, the patient will first undergo surgery to close the wound and remove any debris that may be lodged in the brain. Surgery may also be an option if the head injury has caused a large contusion (bruising of the brain) or hematoma (bleeding in the brain). Surgery is required in almost half of all severe head injuries, according to the National Institute of Neurological Disorders and Stroke (NINDS). Following surgery, patients may be admitted to an intensive care ward where they can be monitored closely for signs of possible complications.

Almost all severe internal head injuries require some form of rehabilitation. In some cases, the head injury may have damaged parts of the brain that control speech, movement and behavior, so patients may need treatment that is specific to these problems. This may include speech therapy or physical therapy. The goal of rehabilitation is to enable the patient to function as well as possible in the home and in society. Rehabilitation programs are usually tailored to meet the requirements and constraints of the patient. They can take place in a hospital, a specialized rehabilitation facility, community center or the patient’s home.

It is common for patients with severe head injury to experience personality changes as a result of the injury. This may require psychotherapy and, in some cases, medication to manage psychiatric problems. It is important that physicians are aware of the patient’s head injury before prescribing medication because side effects are often more severe in people who have sustained head injuries.

Prevention methods for head injury

There are many things which can cause a head injury, some of which are difficult to avoid (e.g. being hit by falling debris). However, many head injuries are preventable.

Safety precautions to avoid head injuries include:

  • Always wear a seatbelt when driving or riding in an automobile. Children should be buckled into an appropriate car seat or booster seat. Seat belts should be worn at an appropriate height, using both the lap belt and shoulder harness, if available.

  • Wear protective head gear when riding a motorcycle or bicycle, or when in-line skating, skateboarding, snowboarding or skiing. The Department of Transport (DOT) recommends that motorcyclists and their passengers wear a DOT certified helmet with a faceguard and protective clothing. Suitable head gear and a mouth guard should also be used when playing contact sports such as football, baseball, boxing or hockey. It is important that helmets are relatively new, in good condition and have not been previously damaged. This could weaken the helmet and make it ineffective in protecting against head injury.

  • Avoid contact with guns or safely store any guns in the house. Guns should always be stored unloaded with the safety lock engaged and, if possible, with an additional trigger lock. They should be contained within a locked box and ammunition should be stored separately.

  • Avoid alcohol and other drugs when operating a vehicle or playing sports. Alcohol impairs cognitive (mental processes) function and may encourage people to take unnecessary risks or act recklessly, thereby increasing the risk of sustaining a head injury.

  • Ensure that the home is safe. Head injuries that are caused by falls (specifically among older people and young children) may be prevented by ensuring that the home is safe. People should be especially concerned with stairways, bathtubs and windows as these are the areas where most falling accidents occur.  In addition, parents of toddlers should take proper steps to childproof the home. For example, padded bumpers should be placed on sharp corners of furniture.

When to call 911

A head injury can be a frightening event for both the injured person and caregivers. Many times, head injuries are minor and may be effectively treated with first aid and close monitoring for signs of serious injury. It is normal for someone who has sustained a head injury to experience some neurological effects such as headache, nausea, short-term confusion and irritability or depression. However, some symptoms may indicate a more severe injury that requires immediate treatment.

Emergency services should be contacted in the following circumstances:

  • Any open head injury, especially if it appears that something may have penetrated the skull. This includes serious injuries sustained as the result of an automobile accident or a gun-shot wound.

  • If a person is unconscious or stops breathing for more than 30 seconds.

  • Severe bleeding from the scalp that will not stop after first aid.

The following symptoms can occur up to several days after the head injury took place. They suggest that the brain has been seriously damaged. People who observe these symptoms in someone who has recently sustained a head injury should contact emergency services:

  • Increasing sleepiness or confusion
  • Persistent vomiting
  • Paralysis or one or more limbs
  • Inability to speak coherently
  • Lack of coordination
  • Clear fluid (cerebrospinal fluid) draining from nose or mouth

Parents of children who sustain head injuries should be especially vigilant. If a child loses consciousness, even for a short period of time, emergency services should be contacted. Loss of consciousness indicates that the brain has suffered trauma and may require immediate treatment.

Questions for your doctor regarding head injury

Preparing questions in advance can help patients to have more meaningful discussions healthcare professionals regarding their condition. Patients may wish to ask their doctor the following head injury-related questions:

  1. Could my symptoms be caused by something other than a head injury?
  2. When will I be able to resume normal activities?
  3. Will there be any long-term effects from my head injury?
  4. What methods will you use to assess the extent of my head injury?
  5. Should I stop taking my usual medications?
  6. Should I avoid any prescription or over-the-counter medications while I recover?
  7. Should I avoid alcohol?
  8. Will my head injury affect my pregnancy?
  9. What should I look out for if my child has sustained a head injury?
  10. Should I keep my child awake after a head injury?
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