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    Head trauma-part-2-1222353463222787-8 Head trauma-part-2-1222353463222787-8 Presentation Transcript

    • Imaging of Head Trauma Part 2: Pathology Rathachai Kaewlai, MD Specialized in Body Imaging and Emergency Radiology rathachai@gmail.com December 2006 The author is willing to receive any input, comments and corrections, Please do not hesitate to contact at the email address provided above. 1Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Checklist for Trauma Brain CT  Have 3 different windows to look for different pathology (brain, subdural and bone windows)  First image includes foramen magnum  Look first for the pathology that needs emergent Rx  Hydrocephalus  Look for primary pathology (hemorrhage in different compartments)  Look for secondary pathology (brain herniation, midline shift)  Look at the mastoid and sphenoid sinuses for hemorrhage which implies skull base fractures  Look at temporomandibular joints for fracture and/or dislocation (this pathology causes significant long term complications) 2Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture • Etiology-Pathogenesis – Direct blow to the skull – Skull vault has 3 layers (outer table, diploe, and inner table) but diploe does not form where skull is covered by muscles (thin area, prone to fracture) – Areas prone to fracture: • Squamous temporal/parietal bones (most common) • Foramen magnum, skull bases, cribiform plates, orbital roofs 3Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture • Epidemiology – Fracture (fx) present in majority of severe head injury cases – Skull fx absent in 1/4 of fatal injuries at autopsy. Absence of skull fracture not excludes brain injury – 1/3 of severely injured patients do not have skull fx – Concomitant cervical spine injury is 15% (cervical spine radiograph or CT may be needed) 4Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture Fracture Suture •Smooth or jagged edge •Serrated edge •Straight line •Curvilinear •Angular turn •Curvilinear •Darker on X-ray •Lighter •Greater in width •Lesser width •Any locations •Specific anatomic location 5Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture • Imaging recommendation – When suspect skull fracture • Head CT (in bone window, and edge enhancement algorithm*) AND Scout CT (to look for fracture ‘in plane’ with axial scan) • Coronal and sagittal reformation is proven to be useful only when the scans were performed in helical mode (most hospitals scan the brain in conventional mode) * Consult your radiologist about the different CT algorithm.Edge enhancement algorithm is useful to detect bony lesions (in bone window) and lung lesions (in lung 6 window).Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture - Linear, nondepressed • Run through the entire thickness of bone • Look if the fx line runs through a vascular channel, venous sinus. (This can cause epidural hematoma, venous sinus thrombosis and occlusion) • Almost always overlying soft tissue edema • Associated with extra-axial hematoma • Axial images of CT may miss fx that is ‘in plane’. Always check scout CT for obvious fx 7Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 34-year-old man, fall from 10ft height Axial CT: linear non-depressed Retrospective review of the fracture (red arrows) of left skull x-ray shows faint fracture parietal bone. Note soft tissue line. hematoma overlying the fracture. 8Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture - Depressed • Fragment (s) depressed inward • Consider open when – Skin laceration over the fracture – Through paranasal sinuses, middle ear structures • Potential surgical elevation in – Depressed > 5 mm and overlies motor or speech areas – Depressed > skull thickness • Causes laceration of dura, arachnoid and possible brain parenchyma 9Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Middle age man, MVA, severe head injury Axial CT (bone window) shows 3D CT, although not needed for diagnosis, helps open depressed fractures (red radiologists and clinicians ‘see’ the complexity of arrows) of the right frontoparietal fractures and plan for treatment. bone and presence of pneumocephalus (blue arrow). Severe soft tissue edema or hematoma. 10Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture - Diastatic • Spreading of suture, 1-2 mm more than normal contralateral side • Coexisting linear fracture possible • May tear dural venous sinus, causing venous epidural hematoma (venous EDH), venous sinus thrombosis or occlusion 11Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 35-year-old man, pedestrian hit by a car Axial CT image shows diastasis fractures (red arrows) through left coronal suture and posterior portion of the sagittal suture. Normal suture is shown (blue arrow). Severe soft tissue swelling or hematomas overly the fractures. 12Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture - Basilar • Clue: opacified sphenoid or mastoid • Problem associated: – Dural tear (patients come with CSF otorrhea or rhinorrhea) – Ear ossicles, labyrinth, cranial nerve (V, VI, VII) involvement – Vascular injury- laceration, dissection, occlusion, infarction, carotid-cavernous fistula • Presentation: – Temporal bone fx- CSF otorrhea, bruising over mastoid (Battle sign) – Anterior cranial fossa fx- CSF rhinorrhea, bruising around the eyes (raccoon eyes) 13Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Young man in high velocity MVA with bleeding from the right ear. Axial CT image shows the most common type of skull base fx; longitudinal fx (blue arrows) through the right temporal bone. Note disruption of the right ear ossicles (red arrow). Blood in bilateral sphenoid sinuses imply fractures through the sinuses. There is no fracture through the right carotid canal (C). If there is a suspicion of fracture through the carotid canal, CT angiography should be performed to rule out vascular injury. 14Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Skull Fracture - Pneumocephalus • Presence of air or gas in the cranial cavity • Principal cause = trauma • Indicates communication between intracranial and extracranial spaces, e.g. paranasal sinuses or ambient air • Significant complications: meningitis, CSF otorrhea or rhinorrhea 15Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Small pneumocephalus (red arrows) is seen in the subarachnoid space of the right frontal convexity. This patient had right frontal sinus fracture as a source of pneumocephalus. Presence of pneumocephalus should raise the suspicion of sinus fracture or open fracture to the ambient air. 16Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Epidural Hematoma (EDH) • Etiology-pathogenesis – Source of bleeding most commonly middle meningeal artery (85-90%) > others (dural sinus - venous EDH) – Hematoma between inner table of the skull and dura – Underlying brain usually minimally injured. Good prognosis if treated aggressively – May cross midline and dural attachment – Not cross sutures (exception: diastatic fx, large EDH) – Most common location = squamous part of temporal bone 17Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Epidural Hematoma (EDH) • Epidemiology: – Young men (20-40’s) - older people dura strongly adheres to inner table of the skull – Majority has skull fx • Clinical features: – Significant trauma – Loss of consciousness; Lucid interval found in 40% of patients – Delayed development 10-25%, within the first 36 hours 18Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Epidural Hematoma (EDH) • CT findings – Hyperdense biconvex extra-axial mass – Low density area inside hematoma represents active bleeding (swirl sign) – Common to have herniation • Potential indications for surgery – Size > 2 cm – Active bleeding – Pending herniation – Corresponding neurological deficit 19Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Epidural Hematoma (EDH) • Venous EDH – Usually in posterior fossa – Depressed skull fx causes strip of the dura, giving potential space for blood accumulation – Tear of venous sinus (lhigh flow, low pressure) – More benign course, subacute presentation, usually not required surgery 20Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Young patient in MVA Axial CT image shows a large lentiform-shaped homogeneous hyperdense mass in the right temporal convexity, consistent with epidural hematoma (red arrows). Nonvisualized temporal horn of the right lateral ventricle implies mass effect from the hematoma and degree of brain edema. Fracture is identified at the right squamous temporal bone (not shown). 21Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 35-year-old man, fall from 12ft Axial CT image shows a small lentiform-shaped homogeneous hyperdense mass in the left parieto-occipital convexity, consistent with epidural hematoma (red arrows). The proximity of the hematoma to the transverse sinus raises the possibility of dural venous sinus injury. Subsequent MRV and CTV show no evidence of venous sinus injury. The patient was discharged home. 22Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Subdural Hematoma (SDH) • Etiology-pathogenesis: – Blood collects between dura and arachnoid – Source of blood - torn cortical bridging veins, artery may also be torn • Epidemiology: – Extremes of age - infant or elderly – Usually coexists with other brain injuries, i.e. subarachnoid hemorrhage 23Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Subdural Hematoma (SDH) • CT findings: – Acute SDH - crescent blood collection over hemisphere, displacing the cerebral cortex medially – Usually hyperdense (can be mixed due to unclottted blood or torn arachnoid) – Can be isodense if patients are anemic or blood mixes with CSF – Can cross suture – Can extend into interhemispheric fissure (thick falx), along tentorium 24Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 35-year-old man, fall from height Axial CT image shows a thin concave hematoma along the left temporal convexity, representing subdural hematoma (red arrows). 25Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 35-year-old man, fall from height Axial CT image (subdural window) shows thin bilateral hyperdense blood along the right parietal and left temporal convexities, representing acute subdural hematoma (red arrows). Small subarachnoid hemorrhage is also noted in the sulci of the right parietal lobe (blue arrow). Bilateral subdural hematoma can be subtle and easily missed on ‘brain window’. 26Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Traumatic Subarachnoid Hemorrhage (tSAH) • Etiology-pathogenesis: – Tear of veins in subarachnoid space • Epidemiology: – Most common cause of subarachnoid hemorrhage is trauma – tSAH usually associated with cerebral contusion, SDH, or other lesions. Nearly all cases of tSAH have other lesions to suggest traumatic cause – Isolated SAH in trauma patients; there is a possibility of ruptured aneurysm causing sudden loss of consciousness and then later trauma (ruptured aneurysm while driving, or having activities) 27Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Traumatic Subarachnoid Hemorrhage (tSAH) • CT findings: – High density blood in sulci/cisterns – Location - next to contusion or under SDH/skull fx/scalp laceration (otherwise, look similar to aneurysmal SAH) – Traumatic intraventricular hemorrhage (tIVH) can coexist • Seen as blood-CSF level in the ventricles – Subtle tSAH • Blood in the interpeduncular fossa may be the manifestation of subtle SAH 28Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 58-year-old man, found down at home Coronal reformatted CT image shows subarachnoid hemorrhage insinuated in the cerebral sulci of left parietal and right temporal lobes. Ruptured cerebral aneurysm is the main differential diagnosis in the patients presenting with pure subarachnoid hemorrhage with equivocal history of trauma. 29Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Cerebral Contusion • Etiology-pathogenesis: – Initial injury causes the contusion due to cerebral gyri impact inner table of the skull (rough edges and ridges) – Evolve from petechial hemorrhage -> small hemorrhage -> large hematoma (imaging worsened with time) – More evident after 24h • Epidemiology: – Most common parenchymal lesion in head trauma 30Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Cerebral Contusion • CT findings – Low density cortex (edema) mixed with high density blood (petechial hemorrhage) – Classic location: anterior base of frontal and temporal lobes – Multiple, bilateral – Can be normal early – Can be non-hemorrhagic • MRI is better for detection, delineating extents of contusions 31Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 38-year-old man, fall from height Axial CT image shows an ill- defined area of hypodensity and loss of grey-white matter differentiation in the tip of the left temporal lobe (red arrows); a typical location of this non- hemorrhagic contusion. Contusion without hematoma is difficult to appreciate on CT scan. MRI is more sensitive. 32Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Middle age man, fall from height Hemorrhagic contusion (red arrows) at the frontal bases, right more than left, is noted as an ill-defined area of hypodensity in CT and high signal intensity zone in MRI T2- WI. MRI is more sensitive to depict the extent of this injury. 33Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Diffuse Axonal Injury (DAI) • Frequent cause of persistent vegetative state and morbidity in traumatic brain injury patients • Etiology-pathogenesis – Traumatic deceleration injury: shearing/rotational forces in areas of greater density differential in the brain (= grey-white matter interface) • Can be an isolated finding in traumatic brain injury – No (or little) association with presence of subarachnoid, subdural hemorrhage, or skull fracture 34Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Diffuse Axonal Injury (DAI) • Clinical features – Usually results in instantaneous loss of consciousness. Clinical symptoms worse than CT findings – Most patients (90%) remains in vegetative state (rarely causes death because brainstem function typically unaffected) • General imaging features – Can be either hemorrhagic or non-hemorrhagic (the latter is more common) – Grey-white matter interface, brain stem, corpus callosum – Number and location of lesions predict prognosis (worst when multiple, and in supratentorial location) 35Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Diffuse Axonal Injury (DAI) • CT findings – May be normal (microscopic, nonhemorrhagic lesions can be missed by CT) – Small hemorrhagic foci in typical locations • MR findings – MRI is the imaging of choice to detect DAI – Susceptibility sequence needed for detection of hemorrhagic DAI (called T2 GRE, or T2*). Hemorrhagic lesions will be dark. – Non-hemorrhagic lesions are bright on T2-WI and FLAIR T2 GRE = T2 gradient echo, T2* = T2 star 36Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Diffuse Axonal Injury (DAI) • Imaging recommendation for suspected DAI – When initial brain CT is normal but the patient is in vegetative state • MRI with susceptibility sequence OR • Follow up brain CT in 24 hours (1/6 of DAI will evolve, may be seen in subsequent CT) 37Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 24-year-old woman, MVA, severe head injury, GCS 4T Axial CT image shows mild diffuse Same day MRI (Susceptibility brain swelling without intracranial sequence) shows multiple tiny areas hemorrhage. Small subgaleal of blood products (red arrows) in the hematoma is present (red arrow). grey-white matter junctions and deep grey nuclei consistent with DAI. Blue arrow represents a vascular flow void. Blue star is an artifact. 38Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Vascular Effects of Trauma • Hemodynamic alterations common with traumatic brain injury • Spectrum of vascular abnormalities due to trauma – Vasospasm, ischemia, infarction – Pseudoaneurysm, arterio-venous fistula – Laceration, dissection • Ischemia/infarction due to… – Vasospasm – Embolism from vascular injury – Secondary to brain herniation 39Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 39-year-old man, fall from height Axial CT image done at day 2 after the injury shows a large right middle cerebral artery territory infarction (red arrows), in conjunction with acute subdural (blue star) and intraparenchymal hemorrhage in the right frontal base. The high density structure in the left parasagittal region is a part of an intracranial pressure monitoring device. 40Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Cerebral Edema • Increased brain water (astroglial swelling) • Two types (vasogenic and cytotoxic edema) often coexists • In trauma: – Vasogenic edema occurs immediately then cytotoxic edema within hours – Usually adjacent or mixed with brain contusion – Generally resolves within 2 weeks 41Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 23-year-old woman, MVA Axial CT image shows edematous brain with loss of grey/white matter interface (red stars), compressed ventricle (arrow) and effacement of the sulci (not seeing any cerebral sulci) in this patient who had DAI confirmed by MRI. 42Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Herniations • Usually more deteriorating than primary injury • Etiology-pathogenesis – Hemorrhage accumulates within closed space, CSF spaces compressed then mechanical displacement of brain occurs – May cause secondary ischemia or infarction – If not correct, brain death 43Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Midline Shift & Subfalcine Herniation Axial CT image shows a midline shift to the left due to large right extra-axial hemorrhage (red stars) and intraparenchymal hemorrhage. The degree of midline shift (red line) is usually measured at the level of maximal deviation of the midline structure (septum pellucidum is a useful anatomy). Subfalcine herniation is defined as herniation of cingular gyrus (blue star) underneath the falx cerebri. Presence of midline shift usually signify subfalcine herniation, and vice versa. ACA occlusion may become occluded. 44Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Obstructive Hydrocephalus & Descending (central) transtentorial herniation Hydrocephalus is one of the most emergent finding to look for, because it is treatable. This patient had dilated left lateral ventricle from asymmetric brain edema (right more than left). Central herniation is defined as both temporal lobes descend through the tentorial incisura, which can be seen as effacement of the cistern around the midbrain (star). 45Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Tonsillar Herniation Make sure the lowest cut of CT image includes foramen magnum! Presence of space- occupying lesion in the brain, cerebellar tonsils (red stars) in the same cut as foramen magnum, obliteration of CSF space and displaced portions of cervicomedullary junction (M) are signs of tonsillar herniation. Tonsils can be low lying as a normal variation or a Chiari malformation. 46Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • Brain Death • Etiology-pathogenesis: – Severe increased ICP decreases cerebral blood flow, then irreversible loss of brain function • Clinical criteria: coma + absent brainstem reflexes + apnea test • Imaging may confirm but does not substitute for clinical criteria • CT findings: – No flow in intracranial arteries/venous sinuses – Diffuse cerebral edema – Hyperdense cerebellum (much denser than cerebrum) 47Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • 49-year-old woman, ruptured cerebral aneurysm Contrast-enhanced axial CT (Left) shows diffuse SAH (blue stars) in the cerebral cisterns, diffuse cerebral edema. There is no intracranial blood flow either in arteries or venous sinuses. Both images show normal enhancement of extracranial vessels (red arrows). The patient had bilateral ventricular shunt placement. 48Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD
    • • The information provided in this presentation… – Does not represent the official statements or views of the Thai Association of Emergency Medicine. – Is intended to be used as educational purposes only. – Is designed to assist emergency practitioners in providing appropriate radiologic care for patients. – Is flexible and not intended, nor should they be used to establish a legal standard of care. 49Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD