Traumatic Cerebral Ischemia/Infarction

KEY FACTS

TERMINOLOGY

• Posttraumatic cerebral ischemia (PTCI)

• Hemodynamic alterations induced by traumatic brain injury

(TBI)

○ Can be local, regional, generalized perfusion alteration(s)

IMAGING

• Best diagnostic clue: Restricted diffusion

• Most commonly occurs in PCA vascular distribution

○ MCA and ACA, vertebrobasilar relatively common

○ Less common: Perforating, cerebellar arteries

• Best imaging tool: MR + DWI/ADC

○ Diffusion most sensitive sequence

○ Midsagittal imaging to evaluate for herniation

TOP DIFFERENTIAL DIAGNOSES

• Nontraumatic ischemia/infarction; vascular (multiinfarct)

dementia

• Atherosclerotic occlusion

• Subarachnoid-induced vasospasm

PATHOLOGY

• Primary TBI = direct damage at time of trauma

• Secondary brain injury occurs after initial trauma

○ Due to systemic responses to initial injuries

○ PTCI may be most common cause of secondary brain

injury in setting of severe TBI

○ Secondary injuries often more devastating than primary

TBI

○ Secondary injury can occur after negative initial imaging

• Mechanical shift of brain with herniation across falx &/or

tentorium → 80-90% of PTCI

CLINICAL ISSUES

• Most common sign: GCS ≤ 8

• Symptoms often delayed 12-24 hours to several weeks

• PTCI occurs in 1.9-10.4% of craniocerebral trauma

• Ischemic damage present in 90% of TBI deaths

(Left) Submentovertex view of

autopsied brain in a patient

with uncal herniation ﬊ and

occlusion of the adjacent

posterior cerebral artery (PCA)

﬈ against the tentorium

shows a secondary

hemorrhagic infarct in the

ipsilateral occipital lobe ﬉.

(Courtesy R. Hewlett, MD.)

(Right) Axial NECT in a patient

with a large mixed-age

subdural hematoma shows

herniation of the right uncus

﬇ and compression of the

ipsilateral PCA ſt.

(Left) Lateral DSA shows an

inferiorly displaced PCA ﬊

secondary to descending

transtentorial herniation of

the adjacent temporal lobe.

Note the points at which the

herniated PCA passes over the

edge of the tentorium ﬈. The

distal PCA is severely kinked

and narrowed ﬉. Worsening

herniation will occlude the

PCA and result in secondary

infarction. (Right) Axial NECT

scan in a patient with severe

bifrontal traumatic contusions

shows a right PCA infarct ﬇.

Trauma, and Stroke

Brain: Pathology-Based Diagnoses: Malformations,

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