head trauma imaging
DESCRIPTION
Lecture slideshow for medical students. Basic radiological imaging of head trauma, using xray, ct scan MRI and ultrasound studies.TRANSCRIPT
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