Traumatic Brain Injuries

Traumatic Injuries to the Brain
Causes of TBI

  • 80% of traumatic brain injuries (TBI) relate to:

    1. Motor Vehicle Crashes

    2. Falls

    3. Struck by or against an object

    4. Assault and self-harm

Mechanisms of Injury

  • Coup-Contre Coup: Injury at impact site and opposite side due to brain's motion.

  • Deceleration: Head stops quickly, brain collides with skull.

  • Rotation: Head is twisted.

  • Penetration Injury: Object breaches skull and brain tissue.

Primary Brain Injuries

  • Laceration: Tear in brain tissue.

  • Fracture: Skull break, risk of hematoma.

  • Concussion: Temporary loss of consciousness or brain dysfunction.

  • Contusion: Brain bruise from impact.

  • Diffuse Axonal Injury: Widespread axon damage from acceleration/deceleration.

Hematomas (Blood Collections)

  • Epidural Hematoma:

    • Blood between dura mater and skull.

    • Often arterial, requires surgical evacuation.

    • Symptoms: headache (HA), decreased level of consciousness (LOC), seizures, vomiting, hemiparesis, pupillary dilation.

  • Subdural Hematoma:

    • Bleeding between dura and arachnoid layers.

    • Common in elderly and alcoholics (history of falls/medications).

    • Treatment: burr holes or craniotomy.

  • Intracerebral Hematoma:

    • Bleeding within brain tissue (e.g., penetrating trauma).

    • Requires surgical intervention and ICP monitoring.

Initial Management of Severe Brain Injury

  • Priority Actions:

    • Immediate neurological assessment.

    • Airway management (CRITICAL).

    • Address hypotension (text{MAP} < 65 \text{ mm Hg}) immediately.

  • For Severe Brain Injury (GCS ≤\le 8):

    • Endotracheal intubation (to control PaCO<em>2=35 mm HgPaCO<em>2 = 35 \text{ mm Hg} and adequate O</em>2O</em>2).

    • Fluid resuscitation, sedation, pharmacologic paralysis.

    • Emergency surgeries if herniation/deterioration evident.

    • Hyperventilation and mannitol (1 g/kg1 \text{ g/kg}) for specific conditions.

Glasgow Coma Scale (GCS)

  • Components: Eye opening, verbal response, motor response.

  • If GCS < 8: Immediate intubation.

  • Motor Function: Assess reactions to commands/pain: local, withdraw, decorticate, decerebrate, flaccid.

    • Decorticate Posturing: Arms flexed towards body (damage to thalamus/cerebral hemispheres).

    • Decerebrate Posturing: Arms extended away from body (damage to midbrain/pons) - WORSE PROGNOSIS.

Cranial Nerve & Brainstem Assessment

  • Nerve II (Optic) & III (Oculomotor): Pupil constriction, reaction to light, accommodation.

  • Nerve V (Trigeminal): Corneal reflex.

  • Nerve VII (Facial): Facial symmetry.

  • Nerve IX (Glossopharyngeal) & X (Vagus): Gag reflex, airway protection.

  • "Blown Pupils": Dilated, non-reactive pupils - sign of oculomotor damage or brainstem herniation.

  • Oculocephalic (Doll's Eyes): Eyes do not move with head turning = severe brainstem dysfunction.

  • Oculovestibular (Ice Water Test): Lack of eye movement with ice water in ear = loss of brainstem activity.

Respiratory Assessment (Impact of Brain Injury)

  • Cerebral Damage: Cheyne-Stokes respiration.

  • Pons Damage: Gasping, hyperventilation, or apnea.

  • Medulla Damage: Uncoordinated deep/shallow breathing with irregular pauses.

Imaging and Diagnostics

  • CT Scan: Detects contusions, fractures, acute bleeds, lesions.

  • MRI: Better for soft tissue and multi-planar visualization.

  • Electroencephalography (EEG): Diagnoses seizure disorders, brain death.

  • Lumbar Puncture: Detects blood in CSF, relieves ICP.

Secondary Brain Injury (Worsening Factors)

  • Causes: Increased ICP (often from cerebral edema), hypo/hyperglycemia, hypotension (MAP < 65 \text{ mm Hg}), hypoxia, infection.

Intracranial Pressure (ICP) & Cerebral Perfusion

  • Key Components of ICP: 3-10% cerebral blood, 8-12% CSF, 80% brain parenchyma (water).

  • Cerebral Perfusion Pressure (CPP): Must be 60−100 mmHg60-100 \text{ mmHg} (CPP = MAP - ICP).

Increased ICP

  • Causes: Cerebral edema, tumors, infections, ischemic/hypoxic injuries, brain herniation.

  • Clinical Manifestations: Restlessness, headache, nausea, drowsiness, pupillary changes (irregular shape, blown pupils).

Monitoring ICP

  • Factors that Increase ICP: Hypoxia, hypercapnia, pain, seizures, fever, straining, increased stimulation.

  • Normal ICP: 0−15 mm Hg0-15 \text{ mm Hg}; intervention required for levels >20 \text{ mm Hg}.

  • Monitoring Setup: Invasive catheter into ventricles, leveled at foramen of Monro.

  • Risks: Infection, hemorrhage.

Nursing Considerations for ICP Monitoring

  • CSF Drainage: Check hourly, rebalance every 2-4 hours.

  • Positioning: Head of bed (HOB) at 30 degrees to promote drainage, ensure HOB is stable.

Management of Elevated ICP

  • Strategies:

    • Drain CSF.

    • Osmotic Therapy: Hypertonic saline (>3\% requires central line) and mannitol (monitor for dehydration).

    • Respiratory Support: Prevent VAP, monitor arterial blood gases (ABGs).

    • Sedation Protocol: Continuous sedation/analgesia, use sedation scales, schedule sedation vacations.

    • Neuromuscular Blockade (NMB): Assess with train-of-four every 4 hours.

Pharmacological Interventions for ICP

  • Sedatives & NMBs, antiseizure medications, mannitol, hypertonic saline.

Paroxysmal Sympathetic Hyperactivity (Sympathetic Storming)

  • Clinical Manifestations: Diaphoresis, agitation, restlessness, abnormal posturing, hyperventilation, transient tachycardia/fever.

  • Triggers: Suctioning, elevated temperatures, turning, alarm sounds.

  • Management: Minimize sensory stimuli, hyper-oxygenate during suctioning, limit visitation, manage temperature.

Immediate and Long-Term Effects of Brain Injury

  • Cognitive: Memory, attention, executive function deficits, reduced processing speed.

  • Physical: Motor impairments, fatigue, headaches, sleep disturbances.

  • Emotional/Behavioral: Personality changes, emotional dysregulation, social withdrawal.