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ABPN Neurocritical Care

Severe Traumatic Brain Injury & Contusions

Q: A 24-year-old male is admitted to the neuro-ICU following an assault. He sustained a blow to the right temple, suffered a brief loss of consciousness, woke up alert, but two hours later became obtunded with a GCS of 7. Head CT demonstrates a biconvex, hyperdense extra-axial collection along the right temporal squamosa measuring 35 mL in calculated volume, with 6 mm of midline shift and compression of the ipsilateral uncus. Which of the following statements regarding the pathophysiology and management of this lesion is most accurate according to Brain Trauma Foundation guidelines?

Emergent surgical evacuation via craniotomy is indicated regardless of GCS score because the hematoma volume exceeds 30 mL.. According to the Brain Trauma Foundation surgical management guidelines, an acute epidural hematoma (EDH) with a calculated volume greater than 30 mL must be surgically evacuated regardless of the patient's Glasgow Coma Scale (GCS) score. An EDH is most commonly caused by traumatic laceration of the middle meningeal artery beneath a temporal bone or pterion fracture. It produces a lenticular (biconvex) collection limited by cranial sutures where the dura is firmly adherent. A volume > 30 mL carries a high risk of rapid uncal herniation and brainstem compression, rendering emergent craniotomy mandatory without delaying for ICP monitor placement or conservative trials.

Q: A 19-year-old unrestrained passenger involved in a high-speed rollover motor vehicle collision remains in a deep, unarousable coma (GCS 4T, decerebrate posturing) 48 hours after trauma. Non-contrast head CT shows only subtle effacement of the hemispheric sulci without large extra-axial hematomas or midline shift. Brain MRI with Susceptibility-Weighted Imaging (SWI) demonstrates multiple punctate hypointense microhemorrhagic foci within the lobar parasagittal white matter, the splenium of the corpus callosum, and the dorsolateral rostral midbrain tegmentum. What is the correct Adams histopathological grade of this patient's injury, and what is its prognostic significance?

Grade III diffuse axonal injury; indicates severe rotational shearing involving the brainstem and carries a high risk of persistent vegetative state or severe disability.. The Adams histopathological classification grades diffuse axonal injury (DAI) based on the depth of tissue shearing from rotational acceleration-deceleration forces: Grade I involves axonal injury confined to the lobar white matter (parasagittal gray-white junction); Grade II involves lobar white matter plus the corpus callosum (particularly the splenium and posterior body); and Grade III involves lobar white matter, corpus callosum, and the dorsolateral rostral brainstem (superior cerebellar peduncles and rostral midbrain tegmentum). Involvement of the dorsolateral midbrain tegmentum disrupts ascending reticular activating system (ARAS) pathways, causing immediate, profound coma and carrying a grave prognosis with high rates of persistent vegetative state, severe motor disability, or death.

Q: A 38-year-old female with severe traumatic brain injury from a motorcycle crash underwent emergent right craniotomy for evacuation of an acute subdural hematoma and right frontal contusion. She is intubated in the neuro-ICU and was initiated on intravenous levetiracetam for post-traumatic seizure prophylaxis. On post-injury day 8, she remains obtunded but exhibits no motor twitching. Continuous video-EEG monitoring over the past 48 hours shows diffuse slowing without epileptiform discharges or electrographic seizures. What is the most appropriate management of her antiseizure medication at this juncture?

Discontinue levetiracetam now, as seizure prophylaxis beyond 7 days does not prevent late epilepsy and incurs unnecessary drug toxicity.. Brain Trauma Foundation guidelines recommend a 7-day course of antiseizure medication (such as levetiracetam or phenytoin) to prevent early post-traumatic seizures (seizures occurring within the first 7 days post-injury) in severe TBI. Numerous randomized trials have conclusively proven that prophylactic anticonvulsants do not reduce the incidence of late post-traumatic epilepsy (unprovoked seizures occurring after day 7) and do not improve long-term survival or functional outcomes. In the absence of clinical seizures or electrographic seizures on continuous EEG, antiseizure prophylaxis should be discontinued after day 7 to avoid adverse drug events, cognitive suppression, and drug interactions.

Key Takeaways

Primary brain injury results from immediate contact impact and rotational acceleration forces causing irreversible tissue laceration and axotomy, whereas secondary injury cascades (glutamate excitotoxicity, mitochondrial failure, free radical injury, and cerebral edema) represent the therapeutic targets of neurocritical care.
Brain Trauma Foundation (BTF) 4th Edition Guidelines mandate treating intracranial pressure (ICP) exceeding 22 mmHg, targeting a cerebral perfusion pressure (CPP) of 60 to 70 mmHg, and maintaining systolic blood pressure (SBP) at or above 100 mmHg (ages 50–69) or 110 mmHg (ages 15–49 or ≥ 70).
Surgical evacuation thresholds differ fundamentally: an epidural hematoma (EDH) requires emergent evacuation if volume exceeds 30 mL regardless of GCS, whereas an acute subdural hematoma (ASDH) mandates evacuation if thickness exceeds 10 mm or midline shift exceeds 5 mm regardless of GCS.
Diffuse axonal injury (DAI) results from angular shearing strains classified by Adams histopathology into Grade I (lobar white matter), Grade II (corpus callosum, particularly splenium), and Grade III (dorsolateral rostral brainstem), best visualized on MRI susceptibility-weighted imaging (SWI).
Post-traumatic seizure (PTS) prophylaxis with levetiracetam or phenytoin is indicated for exactly 7 days to suppress early post-traumatic seizures; it does not reduce late post-traumatic epilepsy and must be discontinued after day 7 if no clinical or electrographic seizures occur.

Last updated: October 2026

Severe Traumatic Brain Injury & Contusions

Severe traumatic brain injury ( $TBI$ ), defined by a post-resuscitation Glasgow Coma Scale ( $GCS$ ) score $\le 8$ , is a major cause of death and disability. Neurocritical care focuses on halting secondary injury while identifying surgical mass lesions requiring emergent operative decompression.

Biomechanical Forces and Primary vs. Secondary Injury Cascades

TBI evolves through two distinct pathophysiological phases:

Primary Brain Injury

Primary injury occurs at the instant of impact. Biomechanical mechanisms include contact impact (skull fractures, extradural hematomas, coup contusions) and rotational acceleration-deceleration forces (tissue shearing, subdural hematomas, diffuse axonal injury). These forces cause immediate, irreversible physical damage: parenchymal laceration, vascular disruption, and mechanical axotomy. Primary damage cannot be reversed; management focuses on secondary prevention and rapid surgical triage.

Secondary Brain Injury Cascades

Secondary injury evolves over hours to days, driven by systemic insults (hypotension, hypoxemia, hyperthermia, hypercapnia) and cellular cascades:

Glutamate Excitotoxicity: Massive depolarization and impaired astrocytic uptake cause extracellular glutamate accumulation. Overactivation of $NMDA$ and $AMPA$ receptors drives massive intracellular calcium ( $Ca^{2+}$ ) and sodium ( $Na^+$ ) influx.
Mitochondrial Dysfunction: Intracellular $Ca^{2+}$ overload collapses the mitochondrial membrane potential, opens the permeability transition pore ( $mPTP$ ), arrests $ATP$ synthesis, and releases cytochrome c to trigger apoptosis.
Free Radical Injury: Impaired electron transport generates reactive oxygen and nitrogen species ( $ROS/RNS$ ), inducing cell membrane lipid peroxidation.
Neuroinflammation & Edema: Cytokines ( $IL\text{-}1\beta$ , $TNF\text{-}\alpha$ ) and microglial activation disrupt the blood-brain barrier ( $BBB$ ), compounding cytotoxic cellular swelling with vasogenic edema and precipitating intracranial hypertension.

Brain Trauma Foundation Guidelines: ICP, CPP, and SBP Targets

The Brain Trauma Foundation ( $BTF$ ) 4th Edition guidelines establish evidence-based resuscitation thresholds for severe TBI:

Parameter	BTF 4th Edition Target	Clinical Rationale
ICP Threshold	Treat when $ICP > 22\text{ mmHg}$	Sustained $ICP > 22\text{ mmHg}$ is independently associated with herniation and increased mortality.
CPP Target	Maintain $CPP = 60\text{--}70\text{ mmHg}$	$CPP < 60\text{ mmHg}$ causes secondary cerebral ischemia; targeting $CPP > 70\text{ mmHg}$ with fluids/pressors increases the risk of $ARDS$ five-fold.
Systolic Blood Pressure (SBP)	$\ge 100\text{ mmHg}$ (age $50\text{--}69\text{ y}$ );; $\ge 110\text{ mmHg}$ (age $15\text{--}49$ or $\ge 70\text{ y}$ )	Age-stratified thresholds optimize cerebral perfusion; hypotension is the single most potent secondary predictor of poor neurological outcome.
Advanced Neuromonitoring	Target $PbtO_2 \ge 20\text{ mmHg}$	Brain tissue oxygen tension $< 15\text{ mmHg}$ denotes cellular hypoxia requiring augmented delivery or metabolic suppression.

Important

Calculate cerebral perfusion pressure as $CPP = MAP - ICP$ . Level the arterial transducer at the external auditory meatus (foramen of Monro) rather than the right atrium to prevent overestimating cerebral perfusion when the head of the bed is elevated $30^\circ$ .

Traumatic Extra-Axial Hematomas & Surgical Evacuation Criteria

Standardized neurosurgical guidelines govern the operative management of traumatic intracranial collections:

Lesion Type	Vascular Source & Imaging Hallmarks	Emergent Surgical Indications
Epidural Hematoma (EDH)	Middle meningeal artery/vein ( $85\%$ ); pterion/temporal fracture; biconvex (lenticular) hyperdensity limited by cranial sutures	Volume $> 30\text{ mL}$ regardless of GCS score;; OR thickness $> 15\text{ mm}$ , midline shift $> 5\text{ mm}$ , or GCS drop $\ge 2$ in non-operative candidates
Acute Subdural Hematoma (ASDH)	Parasagittal bridging cortical veins; cortical lacerations; crescentic hyperdensity crossing cranial sutures	Thickness $> 10\text{ mm}$ OR midline shift $> 5\text{ mm}$ regardless of GCS;; OR GCS drop $\ge 2$ points, pupillary asymmetry, or $ICP > 20\text{--}22\text{ mmHg}$
Traumatic Contusions	Coup/contrecoup impact against orbital roofs/sphenoid wings; inferior frontal & anterior temporal poles	Volume $> 50\text{ mL}$ , midline shift $\ge 5\text{ mm}$ , cisternal effacement, or progressive neurological deterioration / refractory ICP

Clinical Nuances

Epidural Hematoma: An EDH collects between the inner skull table and periosteal dura. Classically, $20\text{--}30\%$ exhibit a "lucid interval"—concussive loss of consciousness followed by temporary lucidity, then rapid uncal herniation (ipsilateral fixed, dilated pupil and contralateral hemiparesis). Evacuate if volume $> 30\text{ mL}$ regardless of GCS.
Acute Subdural Hematoma: An ASDH collects beneath the visceral dura, tracking across sutures. ASDH is frequently associated with severe underlying parenchymal contusion and hemispheric edema, carrying $40\text{--}60\%$ mortality. Evacuate if thickness $> 10\text{ mm}$ or midline shift $> 5\text{ mm}$ .
Contusions & "Blossoming": Contusions occur where brain tissue impacts irregular skull base surfaces. They routinely expand—"blossoming"—over the first 24 to 72 hours due to coalescing petechial hemorrhages and edema. Surveillance head CT within 12 to 24 hours (or immediately upon decline) is mandatory.

Diffuse Axonal Injury: Biomechanics, Grading, and Neuroimaging

Diffuse axonal injury ( $DAI$ ) occurs when rotational acceleration-deceleration forces create dynamic shear strains across tissues of differing densities (gray-white junction). Dynamic membrane stretch disrupts axolemmal permeability, provoking calcium influx, calpain activation, and neurofilament compaction. Swollen axonal varicosities and retraction balls form over 24 to 48 hours, culminating in secondary axotomy and wallerian degeneration.

Adams Histopathological Classification

Grade I: Axonal injury confined to lobar white matter (parasagittal gray-white junction, frontal/temporal lobes).
Grade II: Axonal injury involving lobar white matter PLUS the corpus callosum (predominantly the splenium).
Grade III: Axonal injury involving lobar white matter, corpus callosum, PLUS the dorsolateral rostral brainstem (superior cerebellar peduncles, midbrain tegmentum).

Non-contrast CT is insensitive to DAI, often appearing normal or showing only subtle punctate petechiae ( $< 5\text{ mm}$ ). MRI with Susceptibility-Weighted Imaging (SWI) or gradient-recalled echo ( $GRE$ ) is diagnostic, revealing innumerable hypointense "blooming" microhemorrhages in the callosum and brainstem. Clinically, DAI produces prolonged post-traumatic coma disproportionate to initial CT findings.

Post-Traumatic Seizure Prophylaxis Protocols

Seizures after TBI are categorized by onset timing:

Early Post-Traumatic Seizures (PTS): Occur within 7 days of injury, provoked by acute cortical contusions, blood products, and metabolic derangements.
Late Post-Traumatic Epilepsy (PTE): Occur after 7 days, reflecting chronic gliotic scaring and epileptogenic network remodeling.

Note

The BTF guidelines recommend a 7-day course of prophylactic antiseizure medication (ASM)—using either levetiracetam or phenytoin—to suppress early PTS in severe TBI. However, prophylaxis does NOT reduce late post-traumatic epilepsy or improve overall survival. Prophylactic ASMs should be discontinued on post-injury day 7 if no clinical or electrographic seizures have occurred, preventing cognitive slowing, cytopenias, and unnecessary drug toxicity.

Test Your Knowledge

A 24-year-old male is admitted to the neuro-ICU following an assault. He sustained a blow to the right temple, suffered a brief loss of consciousness, woke up alert, but two hours later became obtunded with a GCS of 7. Head CT demonstrates a biconvex, hyperdense extra-axial collection along the right temporal squamosa measuring 35 mL in calculated volume, with 6 mm of midline shift and compression of the ipsilateral uncus. Which of the following statements regarding the pathophysiology and management of this lesion is most accurate according to Brain Trauma Foundation guidelines?

Conservative medical management with hyperosmolar therapy and ICP monitoring is indicated because the GCS remains above 5.

The hematoma is caused by shearing of parasagittal bridging cortical veins and freely crosses cranial suture lines.

Surgical evacuation should be deferred until invasive intracranial pressure monitoring demonstrates sustained values exceeding 22 mmHg.

Emergent surgical evacuation via craniotomy is indicated regardless of GCS score because the hematoma volume exceeds 30 mL.

Test Your Knowledge

A 19-year-old unrestrained passenger involved in a high-speed rollover motor vehicle collision remains in a deep, unarousable coma (GCS 4T, decerebrate posturing) 48 hours after trauma. Non-contrast head CT shows only subtle effacement of the hemispheric sulci without large extra-axial hematomas or midline shift. Brain MRI with Susceptibility-Weighted Imaging (SWI) demonstrates multiple punctate hypointense microhemorrhagic foci within the lobar parasagittal white matter, the splenium of the corpus callosum, and the dorsolateral rostral midbrain tegmentum. What is the correct Adams histopathological grade of this patient's injury, and what is its prognostic significance?

Grade III diffuse axonal injury; indicates severe rotational shearing involving the brainstem and carries a high risk of persistent vegetative state or severe disability.

Grade II diffuse axonal injury; associated with excellent functional cognitive recovery once secondary edema subsides.

Grade I diffuse axonal injury; microhemorrhages are confined to peripheral gray-white junctions and spare critical deep projection fibers.

Grade IV diffuse axonal injury; represents primary transection of the basilar artery perforating branches within the ventral pons.

Test Your Knowledge

A 38-year-old female with severe traumatic brain injury from a motorcycle crash underwent emergent right craniotomy for evacuation of an acute subdural hematoma and right frontal contusion. She is intubated in the neuro-ICU and was initiated on intravenous levetiracetam for post-traumatic seizure prophylaxis. On post-injury day 8, she remains obtunded but exhibits no motor twitching. Continuous video-EEG monitoring over the past 48 hours shows diffuse slowing without epileptiform discharges or electrographic seizures. What is the most appropriate management of her antiseizure medication at this juncture?

Continue levetiracetam monotherapy for a minimum of 6 months to prevent late post-traumatic epilepsy.

Discontinue levetiracetam now, as seizure prophylaxis beyond 7 days does not prevent late epilepsy and incurs unnecessary drug toxicity.

Add a second agent such as fosphenytoin to achieve dual antiepileptic coverage prior to weaning.

Check a serum levetiracetam trough level and double the maintenance dose to protect against blossoming contusions.

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