BRAIN INJURY, TRAUMATIC

BRAIN INJURY, TRAUMATIC - John Herbert Stevenson, MD
BASICS
DESCRIPTION
• Frequently related to rapid deceleration, as occurs ins motor vehicle accidents or diving accidents; may also be due to blunt trauma.
• Traumatic brain injury (TBI) is a dynamic process with initial bleeding followed by secondary injury due to cerebral edema, continued intracranial bleeding, etc.
• Predicting outcome initially is difficult, and patients may improve for years.
• System(s) Affected: Cardiovascular; Endocrine/Metabolic; Nervous
• Synonym(s): Head injury
ALERT
Geriatric Considerations
• Poorer prognosis with increasing age
• Subdural hematomas are common after fall or blow; symptoms may be subtle.
Pediatric Considerations
Outcome for children is more positive, except in severe TBI.
GENERAL PREVENTION
• Safety education
• Seat belts, bicycle and motorcycle helmets
• Protective headgear for contact sports
EPIDEMIOLOGY
• Predominant age: 15-24 years
• Predominant sex: Male > Female
Incidence
• 200/100,000
• 500,000 hospitalizations and 75,000 deaths per year
RISK FACTORS
Alcohol, prior head injury, contact sports; "heading" soccer balls may cause long-term cognitive loss.
ETIOLOGY
• Motor vehicle accident (50%)
• Falls
• Assault
• Child abuse
- Consider if dropped or fell 4 feet (e.g., off bed, couch) and significant injury present
- Subdural more likely to be abuse
- Any retinal hemorrhage (retinal hemorrhage is not caused by seizures or simple head trauma)
ASSOCIATED CONDITIONS
Alcohol and drug abuse


DIAGNOSIS
SIGNS AND SYMPTOMS
Variable and dependent on degree of injury
History
• Loss of consciousness (LOC)
• External signs of head injury
• Headache
• Vomiting
• Amnesia
• Epidural hemorrhage from blunt trauma is generally acute, 30% with a "lucid interval" (initial loss of consciousness [LOC] followed by recovery of consciousness, then LOC secondary to the intracranial bleed)
• Subdural hemorrhage usually has a slower onset and may present weeks after the initial injury, especially in the elderly.
Physical Exam
• Focal signs and symptoms
• Evidence of increased intracranial pressure (ICP) (elevated BP, decreased pulse rate, or slow or irregular breathing [Cushing triad])only 30% have all 3
• Decorticate or decerebrate positioning (both bad prognostic signs)
• Seizures
• Signs of basilar skull fracture: Raccoon eyes, battle sign, hemotympanum, CSF rhinorrhea or otorrhea (see "Tests")
• Unilateral dilated pupil in an alert patient is not consistent with impending herniation, because such patients are always unconscious.
TESTS
• Neuropsychometric testing when able
• CSF rhinorrhea
- Contains glucose, whereas nasal mucus does not
- Check also for the double-halo sign: Put a drop of nasal discharge on filter paper. If it contains CSF and blood, 2 rings appear, a central ring followed by a paler ring.
Lab
• Evaluate for coagulopathy.
• Drug and alcohol screening
Imaging
• CT, noncontrast, is study of choice to review bone windows, tissue windows, and subdural space
- NEXUS II study has demonstrated 8 clinical criteria that, if all absent, indicate a low likelihood of significant TBI
 Evidence of significant skull fracture (depressed, basilar, or diastatic)
 Altered level of alertness
 Neurologic deficit
 Persistent vomiting
 Presence of scalp hematoma
 Abnormal behavior
 Coagulopathy
 Age >65
• Skull radiographs are not helpful in most cases, but can be done to document child abuse.
Diagnostic Procedures/Surgery
• Placement of ICP monitor when indicated
• Serial neurologic exams
Pathological Findings
• Epidural, subdural, or intraparenchymal hemorrhage
• Coup or contra-coup injury
• Evolving, diffuse axonal injury is a principal cause of neurologic sequelae with mild head trauma.
DIFFERENTIAL DIAGNOSIS
Other causes of coma (e.g., drug overdose, infection, metabolic, vascular causes)
TREATMENT
STABILIZATION
• ABCs take priority over head injury.
• C-spine immobilization should be considered in all head trauma.
GENERAL MEASURES
• Acute management depends on severity of injury. Most patients need no interventions.
• Immediate goal: Determine who needs further therapy, imaging studies (CT), and hospitalization to prevent further injury.
• For the severely injured patient
- Avoid hypotension or hypoxia. Head injury causes increased ICP secondary to edema, and perfusion pressure must be maintained.
- Use normal saline for resuscitation fluid.
- Hyperventilation is controversial, but current literature suggests a short duration of hyperventilation, not below PaCO2 30 mm Hg may be beneficial. Prophylactic hyperventilation for those without signs or symptoms of increased intracranial pressure is contraindicated and may cause additional injury secondary to vasoconstriction.
- Hypothermia: Although no difference is seen in mortality, may have marginal benefit especially in patients with elevated ICP refractory to other methods.
- Seizure prophylaxis does not change outcomes (such as death rates) but may prevent seizures. Consider phenytoin for 1 week postinjury.
- Manage breakthrough seizures with lorazepam.
Diet
As tolerated
Activity
See "Activity" under topic "Postconcussive Syndrome" for sports activity management.
MEDICATION (DRUGS)
First Line
• Pain: Morphine 12 mg IV p.r.n.
• Increased ICP
- 0.252 g/kg (0.251 g/kg in children) given over 30-60 minutes in patients with adequate renal function; should not be used unless there is evidence of increased ICP; prophylactic use is associated with worse outcomes.
- 20-40 mg IV to promote diuresis
- Neither furosemide or mannitol should be given to a hypotensive patient.
- Hypertonic saline 2 mL/kg IV decreases ICP without adverse hemodynamic status and may have beneficial effects on immune system and excitatory neurotransmitters.
• Sedation
- Preferred due to short duration of action allowing serial neurologic exams
• Seizures
- 15 mg/kg IV (1 mg/kg/min IV, not to exceed 50 mg/min). Stop infusion if QT interval increases by >50% () 15 mg/kg IV, not to exceed 150 mg/min, if need rapid infusion due to active seizures
- () 12 mg (0.1 mg/kg in children) IV. Preferred over diazepam.
- 15 mg/kg IV at 25-50 mg/min. May give IM.
• Contraindications: Allergy
Second Line
• Diuretics and IV -blockers (e.g., esmolol or labetalol) can be used to maintain mean arterial pressure between 130-70 mm Hg, which may be helpful. However, nitrates may increase ICP.
• Antibiotics (e.g., cefazolin) should be given if penetrating trauma is present. Prophylactic antibiotics are not useful in basilar skull fractures.
SURGERY
Depends on neurosurgical consult
FOLLOW-UP
DISPOSITION
Discharge Criteria
• Abnormal CT
• Abnormal Glasgow coma scale
• Clinical evidence of basilar skull fracture
• Persistent neurological deficits (e.g., confusion, somnolence)
• Patient with no competent adult at home for observation
• Possibly admit: LOC, amnesia, etc.
• Normal hemocrit with return to normal mental status and responsible adult to observe patient at home (see "Patient Monitoring")
Issues for Referral
Consult neurosurgery for
• All penetrating head trauma
• All abnormal head CTs
PROGNOSIS
• Gradual improvement for many
• 30-50% of severe head injuries may be fatal.
• Prolonged coma may be followed by satisfactory outcome.
• Rehabilitation indicated following a significant acute injury. Set realistic goals.
COMPLICATIONS
• Delayed hematomas
• Chronic subdural hematoma, which may follow even "mild" head injury, especially in the elderly. Often presents with headache and decreased mentation.
• Delayed hydrocephalus
• Emotional disturbances and psychiatric disorders resulting from head injury may be refractory to treatment.
• Seizure disordersin 50% of penetrating head injuries, in 20% of severe closed head injuries, and in 5% of head injuries overall. Hematomas significantly increase risk of epilepsy.
• Second-impact syndrome occurs when the central nervous system loses autoregulation. An individual with a minor head injury is returned to a contact sport and, following even minor trauma (e.g., whiplash), the patient will lose consciousness and herniate within 12 minutes, with a 50% mortality. A similar syndrome of "malignant edema" can occur in children with even a single injury.
PATIENT MONITORING
• Any patient discharged should have "head injury instructions" to watch for symptoms indicating the need for further intervention (e.g., changing mental status, worsening headache, focal findings). Give to a competent surrogate who will observe the patient. A patient who deteriorates is not likely to remember or act on any instructions.
• Schedule regular follow-up.
• The postconcussion syndrome can follow mild head injury without LOC and includes headaches, dizziness, fatigue, and subtle cognitive or affective changes.
• Proper counseling, symptomatic management, and gradual return to normal activities is essential to prevent a posttraumatic neurosis that can become refractory to treatment.
MISCELLANEOUS
• Other notes: The Glasgow coma scale is not a linear scale; a score of 14 (normal being 15) represents a moderately severe injury category.
• See also: Brain injurypost acute care issues; Postconcussive syndrome; Seizure disorders