Traumatic brain injury
Traumatic brain injury is structural or functional brain damage from biomechanical force, graded moderate (Glasgow Coma Scale 9-12) or severe (Glasgow Coma Scale 3-8) when imaging shows contusion, edema, or hemorrhage; management centers on preventing hypotension and hypoxia, controlling intracranial pressure with hyperosmolar therapy and, when refractory, decompressive craniectomy.
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What this article covers
- Overview
Definition: traumatic brain injury (TBI) is temporary or permanent brain damage from biomechanical forces applied to the head and neck, ranging from functional disturbance to gross structural injury on imaging.
- Epidemiology
Leading cause of trauma mortality: TBI is a leading cause of trauma-related death and disability, with moderate and severe injury contributing disproportionately compared with the far more common mild TBI.
- Risk factors
High-energy mechanism: a fall from a height greater than 3 feet or 5 steps, ejection from a vehicle, or being struck as a pedestrian are recognized high-risk mechanisms.
- Pathophysiology
Primary injury: direct mechanical deformation and shearing at impact produces contusion, diffuse axonal injury from rotational shear, and, when a vessel is torn, intracranial hemorrhage.
- Clinical features
Altered consciousness: ranges from confusion to coma, quantified by the Glasgow Coma Scale, which defines severity and guides urgency of intervention.
- Differential diagnosis
Concussion (mild TBI): the milder end of the same spectrum, GCS 13-15, normal head CT, and symptoms resolving within 7 to 10 days, unlike moderate/severe TBI.
- Diagnosis
Establishing basis: diagnosis and severity grading rest on the Glasgow Coma Scale score and loss-of-consciousness duration at presentation (as defined in Overview), correlated with neuroimaging findings.
- Management
First step (stabilization): prevent hypotension and hypoxia from presentation, since normalizing arterial oxygenation (target PO2 greater than 60 mmHg) and blood pressure (target systolic blood…
- Complications
Brain herniation: transtentorial, subfalcine, or tonsillar herniation from mass effect or diffuse edema is the most immediately life-threatening complication and requires emergent treatment.
- Prognosis
Severity predicts outcome: lower initial GCS, longer loss of consciousness, older age, hypotension or hypoxia acutely, and larger hemorrhage volume are all associated with worse outcomes.
- Prevention
Injury prevention measures: seatbelt and helmet use, fall-prevention interventions in older adults, and safe sports practices reduce the incidence and severity of TBI at a population level.
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Related articles
- Concussion
Concussion (mild traumatic brain injury) is a biomechanically induced, temporary alteration of brain function with a normal neurologic examination and, when obtained, a normal head CT. Management is symptom-guided with an early, graduated return to activity; most symptoms resolve within 7 to 10 days.
- Epidural hematoma
Epidural hematoma is an arterial bleed, classically from the middle meningeal artery after a temporal bone fracture, that collects between the skull and dura in a biconvex shape that does not cross suture lines; a lucid interval followed by rapid decline is classic, and a GCS below 9, anisocoria, or hematoma over 30 mL requires urgent surgical evacuation.
- Acute subdural hematoma
Acute subdural hematoma is venous bleeding between the dura and arachnoid membrane from ruptured bridging veins, producing a crescent-shaped collection that crosses suture lines on CT. Older adults and patients with alcohol use disorder or on anticoagulation are most susceptible; a hematoma over 10 mm, a GCS under 9, or pupillary asymmetry mandate immediate surgical evacuation.
- Chronic subdural hematoma
A collection of liquefied blood between the dura and arachnoid that develops over weeks after often-trivial or forgotten trauma, typically in elderly or anticoagulated patients with cerebral atrophy; CT confirms the diagnosis, and burr-hole drainage is the treatment for a symptomatic hematoma with significant thickness or midline shift.
- Status epilepticus
Status epilepticus is a generalized tonic-clonic seizure lasting more than 5 minutes, or repeated seizures without return to baseline, and is a neurologic emergency. Treatment is a timed escalation: IV benzodiazepine first, then an IV antiepileptic drug, then anesthetic coma with continuous EEG if convulsions persist.