Head Trauma
GENERAL PRINCIPLES
Definition
Traumatic brain injury (TBI) can occur with head injury due to contact and/or acceleration/deceleration forces.
Concussion: Trauma-induced alteration in mental status with normal radiographic studies that may or may not involve loss of consciousness.
Contusion: Trauma-induced lesion consisting of punctate hemorrhages and surrounding edema.
Classification
Closed head injuries may produce diffuse axonal injury.
Contusion or hemorrhage can occur at the site of initial impact, coup injury, or opposite to the side of impact, countercoup injury.
Penetrating injuries (including depressed skull fracture) or foreign objects cause brain injury directly.
Secondary increases in intracranial pressure may compromise cerebral perfusion.
Epidemiology
Head injury is the most common cause of neurologic illness in young people.
The overall incidence of TBI in the US population is estimated at approximately 750 per 100,000 (i.e., approximately 2.5 million per year with approximately 11% requiring hospitalization).31
Two-thirds of TBIs are considered mild, whereas 20% are severe and 10% are fatal. Note that although designated as mild, mild TBI can still translate into significant disability (permanent in
15%).
Rates of TBI are highest in the very young, adolescents, and the elderly.
DIAGNOSIS
Clinical Presentation
Patients will often present with confusion and amnesia, including loss of memory for the traumatic event as well as inability to recall events both immediately before and after trauma.
Patients may complain of nonspecific signs including headache, vertigo, nausea, vomiting, and personality changes.
Intracerebral hematomas may be present initially or develop after a contusion.
Epidural hematoma is usually associated with skull fractures across a meningeal artery and may cause precipitous deterioration after a lucid interval.
SDH is most common in aged, debilitated alcoholics and/or in anticoagulated patients. Antecedent trauma may be minimal or absent.
PHYSICAL EXAMINATION
Careful examination for penetrating wounds and other injuries.
Hemotympanum, mastoid ecchymosis (Battle sign), periorbital ecchymosis (raccoon eyes), and CSF otorrhea/rhinorrhea are indicative of a basilar skull fracture.
Neurologic examination should focus on the level of consciousness, focal deficits, and signs of herniation. The GCS should be used for an assessment. Serial examinations must be performed and documented to identify neurologic deterioration.
Degree of impairment due to trauma can be classified using injury severity scores, with GCS being the most common.
Treatment and diagnostic assessment of patients with severe head injury at admission are done according to the Advanced Trauma Life Support protocol.
The Standardized Assessment of Concussion is a standardized tool for the sideline evaluation of athletes who suffer a head injury.
Diagnostic Testing
Head CT should be considered for patients with GCS lt;15 2 hours after trauma, suspected skull fracture, repeated episodes of vomiting after trauma, age greater than 65 years, dangerous mechanism (e.g., pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from #8805;3 feet or #8805;5 stairs), drug or alcohol intoxication, or persistent anterograde amnesia.
Noncontrast head CT scan in the emergency room can rapidly identify intracranial hemorrhage and contusion.
๎ A lenticular-shaped extra-axial hematoma is characteristic of epidural hematoma.
๎ Bone window views may help to locate fractures, if present.
Cervical radiographs with or without CT of the neck must be performed to exclude fracture or dislocation.
MRI can assist in evaluation of TBI patients with persistent sequelae because it is more sensitive for demonstrating small areas of contusion or petechial hemorrhage, axonal inj ury, and small extra-axial hematomas.
TREATMENT
Hospital admission is recommended for patients at risk for immediate complications from head injury. These include patients with GCS lt;15, abnormal CT scan, intracranial bleeding, cerebral edema, seizures, or abnormal bleeding parameters.
When admitted, continuously monitor vital signs and oximetry. ECG should be performed. Arterial pressure monitoring in conjunction with intracranial monitoring may be indicated.
Immobilize the neck in a hard cervical collar to avoid spinal cord injury from manipulating an unstable or fractured cervical spine.
Avoid hypotonic fluids to limit cerebral edema.
Steroids are not indicated for head injury.
Avoid hypoventilation and systemic hypotension because they may reduce cerebral perfusion.
Anticipate and conservatively treat increased intracranial pressure:
๎ Head midline and elevated 30 degrees.
๎ In the mechanically ventilated patient, modest hyperventilation (i.e., PCO2 approximately 35 mm Hg) reduces intracranial pressure by cerebral vasoconstriction; excessive hyperventilation may reduce cerebral perfusion. Remember that these are merely temporizing measures and neurosurgical consultation is always warranted if there is concern for increased intracranial pressure due to head injury.
Neurologic deterioration after head injury of any severity requires an immediate repeat head CT scan to differentiate an expanding hematoma that necessitates surgery from diffuse cerebral edema that requires monitoring and reduction of intracranial pressure.
The use of AEDs in the acute management of TBI can reduce the incidence of early seizures but does not prevent development of epilepsy at a later time. Furthermore, certain AEDs can have adverse effects on cognition, and so these agents should only be used when clinically indicated, with careful consideration of the specific agent chosen. There is no evidence to support AED use for seizure prophylaxis.
Because a second injury, referred to as the second impact syndrome, may lead to severe complications including death, guidelines have been proposed for when individuals can return to play.31
Surgical Management
Neurosurgical consultation is indicated for patients with contusion, intracranial hematoma, cervical fracture, skull fractures, penetrating injuries, or focal neurologic deficits.
In cases of closed head injury complicated by increased intracranial pressure, intracranial pressure monitoring assists medical management.
Evacuation of chronic SDH is determined by the symptoms and degree of mass effect.