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Head injury refers to trauma to the head. This may or may not include injury to the brain. Traumatic brain injury (TBI), also called intracranial injury, occurs when an outside force traumatically injures the brain. TBI can be classified based on severity, mechanism (closed or penetrating head injury), or other features (e.g. occurring in a specific location or over a widespread area). Head injury usually refers to TBI, but is a broader category because it can involve damage to structures other than the brain, such as the scalp and skull. All types of head injuries can be caused by trauma. In adults in the United States such injuries commonly result from motor vehicle accidents, assaults, and falls. In children falls are the most common cause followed by recreational activities such as biking, skating, or skateboarding. A small but significant number of head injuries in children are from violence and abuse.
Penetrating trauma: Missiles such as bullets or sharp instruments (such as knives, screwdrivers, or ice picks) may penetrate the skull. The result is called a penetrating head injury. Penetrating injuries often require surgery to remove debris from the brain tissue. The initial injury itself may cause immediate death, especially if from a high-energy missile such as a bullet.
Blunt head trauma: These injuries may be from a direct blow (a club or large missile) or from a rapid deceleration force (a fall or striking the windshield in a car accident).
Diagnosis and prognosis
Head injury may be associated with a neck injury. Bruises on the back or neck, neck pain, or pain radiating to the arms are signs of cervical spine injury requiring immobilization of cervical spine via application of a cervical collar and possibly a long board. If the neurological exam is normal this is reassuring, however a serious intra-cranial injury may still be present. If the patient developing a worsening headache, has a seizure, develops one sided weakness, or has persistent vomiting than the patient should be advised to return and a CT should be immediately obtained.
In some cases transient neurological disturbances may occur, lasting minutes to hours. Malignant post traumatic cerebral swelling can develop unexpectedly in stable patients after an injury, as can post traumatic seizures. Recovery in children with neurologic deficits will vary. Children with neurologic deficits who improve daily are more likely to recover, while those who are vegetative for months are less likely to improve. Most patients without deficits have full recovery. However, persons who sustain head trauma resulting in unconsciousness for an hour or more have twice the risk of developing Alzheimer’s disease later in life.
Signs and symptoms of head injury: vary with the type and severity of the injury.
• Minor blunt head injuries may involve only symptoms of being “dazed” or brief loss of consciousness. They may result in headaches or blurring of vision or nausea and vomiting. There may be longer lasting subtle symptoms including, irritability, difficulty concentrating, insomnia, and difficulty tolerating bright light and loud sounds. These post concussion symptoms may last for a prolonged period of time.
• Severe blunt head trauma involves a loss of consciousness lasting from several minutes to many days or longer. Seizures may result. The person may suffer from severe and sometimes permanent neurological deficits or may die. Neurological deficits from head trauma resemble those seen in stroke and include paralysis, seizures, or difficulty with speaking, seeing, hearing, walking, or understanding.
• Penetrating trauma may cause immediate, severe symptoms or only minor symptoms despite a potentially life-threatening injury. Death may follow from the initial injury. Any of the signs of serious blunt head trauma may result.
Classification of severity:
Head injuries can be classified into mild, moderate, and severe categories. The Glasgow Coma Scale (GCS), a universal system for classifying TBI severity, grades a person’s level of consciousness on a scale of 3–15 based on verbal, motor, and eye-opening reactions to stimuli. It is generally agreed that a TBI with a GCS of 13 or above is mild, 9–12 is moderate, and 8 or below is severe. The three elements of GCS are described with grade below.
Best eye response (E) : There are 4 grades starting with the most severe:
1: No eye opening
2: Eye opening in response to pain. (Patient responds to pressure on the patient’s fingernail bed; if this does not elicit a response, supraorbital and sternal pressure or rub may be used.)
3: Eye opening to speech. (Not to be confused with an awaking of a sleeping person; such patients receive a score of 4, not 3.)
4: Eyes opening spontaneously
Best verbal response (V) : There are 5 grades starting with the most severe:
1: No verbal response
2: Incomprehensible sounds. (Moaning, but no words)
3: Inappropriate words. (Random or exclamatory articulated speech, but no conversational exchange)
4: Confused. (The patient responds to questions coherently but there is some disorientation and confusion.)
5: Oriented. (Patient responds coherently and appropriately to questions such as the patient’s name and age, where they are and why, the year, month, etc.)
Best motor response (M): There are 6 grades starting with the most severe:
1: No motor response
2: Extension to pain (abduction of arm, internal rotation of shoulder, pronation of forearm, extension of wrist, decerebrate response)
3: Abnormal flexion to pain (adduction of arm, internal rotation of shoulder, pronation of forearm, flexion of wrist, decorticate response)
4: Flexion/Withdrawal to pain (flexion of elbow, supination of forearm, flexion of wrist when supra-orbital pressure applied ; pulls part of body away when nailbed pinched)
5: Localizes to pain. (Purposeful movements towards painful stimuli; e.g., hand crosses mid-line and gets above clavicle when supra-orbital pressure applied.)
6: Obeys commands. (The patient does simple things as asked.)
Interpretation is done by individual elements as well as the sum of the score is important. Hence, the score is expressed in the form “GCS 15 = E4 V5 M6 at 09:00AM”.
Similar systems exist for young children. Other classification systems such as the one shown in the table determine severity based on the GCS after resuscitation, the duration of post-traumatic amnesia (PTA), loss of consciousness (LOC), or combinations thereof. It is also possible to classify TBI based on prognosis or indicators of damage visible with neuro-imaging, such as mass lesions and signs of diffuse injury. Grading scales also exist to classify the severity of mild TBI, commonly called concussion; these use duration of LOC, PTA, and other concussion symptoms.
Clinical Severity of Traumatic Brain Injury
Grade GCS PTA LOC
Mild 13–15 <1 hour <30 minutes
Moderate 9–12 30 minutes–24 hours 1–24 hours
Severe 3–8 >1 day >24 hours
Imaging
The need for imaging in patients who have suffered a minor head injury is debated. A CT of the head should be performed immediately in all those who have suffered a moderate or severe head injury.