Head Trauma Imaging

HEAD

TRAUMA

IMAGING

Ma. Socorro I. Martinez, MD, FPCR, FUSP, FCT-MRISP

•Role of Skull X-rays - debatable

CT• Imaging procedure of choice for acute injury

or neurologic deficit• Quick, easy, reliable & available• Valuable in making a dx, excluding

alternative diagnoses or sequelae of other pathology

• Px monitoring is simple & safe• compatible w/ px stabilization devices• Identification & localization of calvarial fxs &

bony/metallic fragments • Optimal assessment for acute hemorrhage

& mass effect • Contrast infusion rarely indicated

CT may reveal:

• No abnormality (30%) • Areas of edema (10%) • Hemorrhagic contusion (20%) • Extradural or subdural hematoma

(20%) • Combination of the above (20%)

Epidural hematoma

• may present as primary depressed consciousness or ff a lucid interval

• assoc w/ skull fx (calvarium), not always

• usu temporoparietal• Laceration of dural a. or a venous

sinus (middle meningeal a. or one of its branches)

• bld collects b/n inner table of skull & dura (periosteal layer)

• uniformly hyperdense (acute) well-defined biconvex mass; may contain hypodense foci due to active bleeding

• often w/ significant mass effect (compression of ipslateral lat ventricle & dilatation of opp lat ventricle due to obstrxn of foramen of Monro)

• basal cisterns may be effaced

Subdural hematoma

• b/n dura and arachnoid• from ruptured veins crossing

this potential space• more common in elderly - space

enlarges as brain atrophies

Acute subdural hematoma

• can have equally severe consequences due to mass effect, requiring urgent surgery

• Deceleration and acceleration or rotational forces that tear bridging veins

• CT – Crescent-shaped– Hyperdense, may contain

hypodense foci due to serum, CSF or active bleeding

– Does not cross dural reflections

Subacute Subdural Hematoma • may be difficult to visualize by CT -

becomes isodense to normal gray matter as hemorrhage is reabsorbed

• shift of midline structures w/o an obvious mass (subtle)

• contrast may help- enhancement of dura & adj vascular structures, distinct interface b/n hematoma & adj brain

• - Compressed lat ventricle- Effaced sulci- White matter "buckling"- Thick cortical "mantle"

Chronic subdural • etiol not always clear; prob

due to trauma, often minor• vague symptoms & often dev

slowly w/ gradual depression or fluctuation of consciousness

• bilateral in 10% • becomes low density as

hemorrhage is further reabsorbed

• crescentic, often w/ mass effect

• may be loculated• if w/ rebleeding- mixed density

and fluid/sedimentation levels

Intracerebral HemorrhageHemorrhagic contusion

• stretching & shearing injury• most common primary intra-

axial injury• brain impacts on bony ridge

or dural fold• contre coup - directly opp

impact site, subcutaneous hematoma, fx, or EDH

• common locations:- Temporal lobe - ant tip, inf surface, sylvian region- Frontal lobe - ant pole, inf surface- Dorsolateral midbrain- Inf cerebellum

• CT -ill-defined hypodense area mixed with foci of hemorrhage

• Adj SAH common• After 24-48 hrs –

– hmgic transformation or coalescence of petechial hemorrhages into a rounded hematoma is common

Multiple petechial hemorrhages

• may be throughout cerebral hemispheres

• often very small & at grey/white matter interface

• due to shearing injury w/ rupture of small IC vessels

• in a comatose px w/ no other obvious cause - implies severe diffuse brain injury w/ poor prognosis

• Larger hemorrhages in severe trauma; may not be apparent on immediate scan, becomes prominent after a day or two

• MRI more sensitive, part. in the absence of hemorrhage

Diffuse Axonal Injury • "shear injury“• most common cause of significant

morbidity in CNS trauma• 50% of all primary intra-axial injuries • Acceleration, deceleration and rotational

forces • Immediate loss of consciousness is typical • CT may be normal • CT - ill-defined areas of high density or

hemorrhage• occurs in a sequential pattern of locations

based on the severity of the trauma– Subcortical white matter – Posterior limb internal capsule– Corpus callosum– Dorsolateral midbrain

Subarachnoid hemorrhage • alone or in assoc w/ other

IC or EC hematomas• injury of small arteries or

veins on surface of brain• b/n pia & arachnoid

matter• most common cause of

non-traumatic SAH- cerebral aneurysm rupture

• may also be due to ruptured aneurysm or AVM; may have led to subsequent trauma (imptce of history). Cerebral angio

• TRAUMA -most common cause of SAH

• most commonly over cerebral convexities or adj to injured brain (i.e.cerebral contusion)

• CT- focal high density in sulci and fissures, Sylvian fissure, basal cisterns or ventricular system

• may be complicated by hydrocephalus

Intraventricular Hemorrhage

•assoc w/ DAI, deep gray matter injury, and brainstem contusion

• isolated intraventricular hemorrhage may be due to rupture of subependymal veins

Edema

• Focal edema - localized poorly defined areas of low density– MRI more sensitive

• Diffuse edema - esp in children– may be difficult to detect on CT

Infarction

• Infarction in a typical vascular territory may suggest dissection of a vessel, such as the carotid artery after a direct blow to the neck.

Skull Fractures

• linear (more common) or depressed

• Imptce of bone windows • May involve PNS or skull base• Vs. sutures in anatomical

locations (sagittal, coronal, lambdoidal) and venous channels (undulating margins & sclerotic margins)

• Depressed fractures - inward displacement of fx fragments

Depressed skull fractures

Skull base fractures

• not always visible• blood in sinuses is suggestive• prone to dev meningitis &

require antibiotic prophylaxis• If w/ clinical evidence of skull

base fx (eg CSF rhinorrhoea or bleeding from EAM), a normal CT does not exclude such a fx

Pneumocephalus

• indicates an open head injury, such as due to a basal fracture communicating with sinuses or a penetrating injury to vault (eg a bullet wound)

• indicates the need for antibiotics

Petrous temporal bone fractures

•Transverse ; longitudinal•may be associated with post

traumatic deafness• transverse fracture is more

severe in this respect

Orbital blowout fracture

Thank you