1. CORE Case 9 Workshop Erin O’Connor MD Temple University
v. June 7th 2014

2. Learning Objectives
Review the anatomy of the intracranial compartments.
Know the appropriate imaging work up for patients with head trauma
Recognize the appearance of intracranial hemorrhage on CT
Describe the various types and causes of brain herniation

3. Learning Objectives
Recognize the typical changes in appearance of intracranial blood products with age on CT
List criteria that are used in spinal trauma to determine if CT of the cervical spine should be performed
Describe the role of plain radiographs, CT and MRI in cervical spine trauma
Evaluate cervical spine alignment on imaging

4. What imaging modality would you use?
Trauma to the head – 49 year old male, s/p assault with baseball bat to head
What imaging modality would you use?
Q: What imaging modality would you use? A: Non contrast head CT would be used. It has excellent sensitivity for ICH and is widely available, cost effective, short imaging time, and there is relatively easy to quickly selectively rescan slices which have been affected by patient motion artifact.
Q: Why don’t you use contrast? A: Can potentially obscure small hemorrhages

5. Why not use MRI in the setting acute trauma to head?
Q: Why not use MRI in the setting of acute trauma? A: Anatomical imaging with MRI is very sensitive and accurate in diagnosing cerebral pathology in TBI patients but noncontrast head performed first due to greater availability, more cost effective, shorter imaging time, relative ease of performing and capability of quick selective rescan of slices which have been affected by patient motion artifact.

6. What imaging modality should be used?
35 year old male with new onset of seizures, now referred to neurologist. Head trauma 3 months ago.
What imaging modality should be used?
Q: What imaging modality would you use? A: Patient that is seen in the outpatient setting with new onset of seizure and history of remote trauma (3 mos. ago), the appropriate imaging work up would be to get an MRI. MRI has better soft tissue contrast resolution when compared with CT and also has increased sensitivity for subacute and chronic blood products. This is not an emergency and thus the appropriate management is nonemergent MRI to look for areas of encephalomalacia/gliosis (scarring in brain) and old products that may be resulting in new onset of seizure.

7. Use this diagram to review the intracranial compartments: Epidural, subdural, subarachnoid spaces and intra-axial.
If you drill a hole into the skull.
Q: What are we going to go through first? A: Dura
Q: Where is the dura attached to the periosteum? A: Sutures. Have student point out attachment at coronal suture on diagram. This should elucidate why epidural hematomas have biconvex configuration and why they do not cross sutures. Mention that epidural space is a potential space and when there is bleeding into the epidural space, the hemorrhage displaces the dura from the periosteum.
Q: What are we going to pass through next? A: The arachnoid mater. The subdural space too is a potential space, located between the dura mater and arachnoid mater.
When bridging veins tear, the resulting hemorrhage dissects the arachnoid mater from the dura mater and creates a subdural space.
Q: Why don’t subdurals hemorrhages cross falx? A: There is reflection of the dura along the falx.
Q: What do we pass through next? A: The subarachnoid space.
Q: Where should we draw the pia mater? A: Adjacent to surface of brain.
Q: When the term intra-axial is used, it implies that we are deep to what layer of the meninges? A: The pia mater. Outside of the pia is extra-axial.

8. superior sagittal sinus
pia mater
arachnoid mater
dura mater
Meninges:
superior sagittal sinus
subarachnoid space
epidural space
periosteum
subdural space
suture
LABELLED DIAGRAM

9. Use this normal head CT have students identify where the subarachnoid space is – sulci, cisterns etc; and where the subdural space is (parafalcine, along tentorium, along cerebral convexity); this will make it easier for them to correctly identify the compartment where intracranial hemorrhage is found.

10. subarachnoid space

11. subdural space

12. Next three slides are warm up cases before we show students multicompartmental hemorrhage.
Q: What are the imaging findings here? A: Classic epidural; biconvex/lenticular
Q: Where is the epidural space located? A: Between dura mater and periosteum.
Q: What is the source of bleeding (venous or arterial)? A: arterial, often middle meningeal but does not have to be.
Q: Can you point out the sutures on the bone window? A: Have students do this on ipad so that they can see the concept of epidurals contained by the sutures illustrated.
Q: Why do epidurals not cross sutures? A: This is where the dura attaches to the skull. Thus epidurals result in medial bowing of the dura, with dura remaining fixed at its attachment sites.

13. Q: What are the imaging findings
Q: What are the imaging findings? Ask student to describe in terms of density, shape of collection and location. A: Looking for key terms: crescentic shape, hyperdense to brain (indicating the acuity), SDH along cerebral convexity and b/l tentorium.
Q: What defines the subdural space, i.e. where is it located? A: Between the arachnoid mater and the dura mater.

14. Q: Can you describe imaging findings. What space is this hemorrhage in
Q: Can you describe imaging findings? What space is this hemorrhage in? A: Linear areas of hyperattenuation in the left frontal sulci compatible with SAH.
Q What defines the subarachnoid space, i.e. where is it located? A: Between the pia mater and the arachnoid mater.
Q: If this patient did not have history of trauma, what would be your concern? A: Students should list causes of SAH – aneurysm, AVM, vasculopathy, coagulopathy.

15. At this point, we are going to transition into multicompartmental hemorrhage. Have students point out SDH along falx and the SAH in the bifrontal sulci.
Are they able to differentiate the hemorrhage in the two different compartments?

16. Q: Can you describe the imaging findings here
Q: Can you describe the imaging findings here? A: Epidural hemorrhage (left image) and associated temporal bone fracture (right image). Review that epidural are often associate with a fx of calvairum.
Q: What are the signs of mass effect we see here? A: The right lateral ventricle is compressed. The midline is shifted to the left.
Q. What type of hernation is this? A: Subfalcine herniation.
Next slides talk about herniation.

17. Consider having students break up into small groups for 3 minutes and come up with appropriate labeling of different types of herniation diagrammed here (1-6). The red collection represents an epidural hematoma. (1)uncal (2)descending transtentorial (3)subfalcine (4)extracranial (5)ascending transtentorial (6)tonsillar

18. What is subfalcine herniation?
Sometimes when ICH occurs, there is enough mass effect that it result in herniation.
Q: What is subfalcine herniation? A: Subfalcine herniation is when the brain is shifted underneath the falx. It is the same thing as midline shift.
Q: Can you demonstrate where the falx is on the left image?
Q: Can you draw on this normal (left image) what that would look like?
What is subfalcine herniation?

19. falx tentorial incisura tentorium cerebelli
Left image shows falx. Subfalcine herniation = midline shift. This is when the cerebral hemispheres shift under the falx and across the midline. Right image demonstrates the midline and where the midline would move with subfalcine herniation.

20. What is uncal herniation?
Q: What is uncal herniation? A: Uncal herniation is when the medial portion of the anterior temporal lobe is shifted into the suprasellar cistern. It is a subset of descending transtenorial herniation, which is when the cerebral hemisphere crosses the tentorium at the level of the incisura/notich.
Q: Can you point to the tentorium cerebelli and tentorium incisura on the schematic? A: Have students outline.
Q: Can you draw the suprasellar cistern on this normal (right image)? A: Have students outline it.
Q: Can you draw on the normal what uncal herniation will look like? A: The suprasellar cistern should become crowded due to displacement of brain, specifically uncus. This can be uni or bilateral
What is uncal herniation?

21. falx
tentorium cerebelli
tentorial
incisura

22. What are the potential sequela of herniation?
Q: Here in this patient with epidural hemorrhage (left image), epidural + subdural hemorrhage (right image), what type of herniation do we see? A: subfalcine herniation (left) and on a more inferior image (right) we see uncal herniation.
Q. What are the potential sequela of subfalcine herniation? A: Subfalcine herniation can result in hydrocephalus resulting from ventricular compression; infarct in the ACA distribution due to ACA compression (DRAW COURSE OF ACA ALONG MIDLINE SO UNDERSTAND HOW IT GETS COMPRESSED) ; and potentially mass effect on the brain stem.
Q: What are the potential sequela of uncal herniation? A: Infarct in the PCA distribution (DRAW COURSE OF PCA IN AMBIENT CISTERN SO STUDENTS CAN SEE HOW IT IS COMPRESSED) and mass effect on the brain stem. CIRCLE BRAIN STEM ON RIGHT IMAGE SO MASS EFFECT MADE CLEAR.
What are the potential sequela of herniation?

23. What type of herniation is seen on the left image?
Now here on our left image, lets bring our attention to the foramen magnum. We have a normal for comparison on the right. There is soft tissue crowding in the foramen magnum and we do not see CSF.
Q: What type of herniation do you think this is? A: Tonsillar herniation
Q: Can you describe processes which may result in tonsillar herniation? A: Diffuse cerebral and cerebellar edema; mass such as neoplasm or hematoma in the cerebellum
normal
What type of herniation is seen on the left image?

24. Use this to discuss changes which occur in blood products over time
Use this to discuss changes which occur in blood products over time. We know that things which are more dense appear brighter on CT and things which are less dense appear darker.
Q: Where would you place in this rectangle acute, subacute and chronic blood products.
Remind that as blood products age and break down, they become less dense.

25. BLOOD Products of Varying AGES on CT
Acute on chronic SDH.
Q: Can you to point to areas of acute and chronic hemorrhage on these images? A: Bright areas are hyperdense to brain. These areas of acute hemorrhage are superimposed on chronic SDH which is hypodense to brain.
Have them outline the chronic SDH.
Q: What are the signs of associated mass effect on the brain? A: Effacement of sulci in the right cerebral hemisphere, compression of the right lateral ventricle, subfalcine herniation.

26. What are brain contusions?
Q: What are brain contusions? A: As the name implies, contusions are bruising of brain tissue. Contusions are often associated with hemorrhage due to leak of small blood vessels into brain tissue. In contusions, the blood products are intra-axial. Contusions result from traumatic brain injury when the brain collides with adjacent bony protuberances.

27. Where do brain contusions typically occur?
Use this to have students to draw typical locations for hemorrhagic contusions. Annotations should be made in the inferior frontal lobes, in the temporal lobes adjacent to sphenoid ridge (use right side on this slide) and temporal lobe adjacent to mastoid portion of the temporal bone (use left side of brain to demonstrate that on this slide)

28. Q: Can you describe the mechanism of how this left temporal contusion may have occurred?
A: With impact to head,likely from anterior and superior direction, brain is set in motion and then temporal lobe collides inferiorly with temporal bone and results in contusion. Bone window provided so can see bone that brain pushes up against and causes contusion (Bone window is not same exact same cut, is 9 mm inferior to contusion)

29. What is coup contre-coup injury?
Q: What is meant by coup contrecoup injury? A: Coup injury results from the direct impact to the brain. The force of the impact may set the brain in motion and result in the brain colliding with the opposite side of the skull – what is known as the contrecoup injury. Q: Illustrate the vector of force associated with trauma. Ask a student to annotate the resulting contrecoup injury.

30. 62 yo male, s/p seizure with trauma to head
Q: Can you describe how coup, contre coup injury is illustrated on this image? A: We see scalp swelling posteriorly and this is the presumed site of direct impact.. The impact set the brain in motion and it collided with the anterior skull base (planum sphenoidale).

31. Q: What type of image windows do you see here
Q: What type of image windows do you see here? A: bone window (left image), brain window (right image).
Q: What findings do you see on each image? A: Depressed calvarial fracture seen on bone window. Brain window shows the hemorrhagic contusion resulting from the depressed bone fragment.

32. Evolution of blood products with age
Encephalomalacia and presumably chronic blood products (left image) in region of hemorrhagic contusion (right image), adjacent to a depressed skull fracture.
Q: How would you describe the change in appearance of these blood products with age. A: As blood products break down with age, they become less dense. Acute blood products are hyperdense to brain on CT. Subacute blood products are isodense to brain on CT (not shown here). Chronic blood products are hypodense to brain on CT.

33. 23 yo male, s/p fall down steps
Q: Where is this hemorrhage? Is it intra-axial or extra-axial? A: The hemorrhage is intra-axial
Q: Is this a typical location for a hemorrhagic contusion? A: No, this is not a typical location for hemorrhagic contusion and should prompt one to think that the hemorrhage here caused the trauma rather than trauma resulting in hemorrhage. Angiography is next appropriate step. This hemorrhage turned out due to be due rupture of pseudoaneurysm in distal branch of left MCA in this patient that also had history of remote trauma.

34. 10 mos. old female, rolled off of bed
Q: What windows do we have here on this noncontrast head CT A: brain window (left), bone window (right)
Q: How would you describe the hemorrhage here – shape, density? A: Crescent mixed density collection along right cerebral convexity. Mixed density suggests differing ages
Q: What is seen on bone windows? A: Slightly displaced fxs in parietal bone.
Q: Can you point out the sutures? A: Have students circle sutures, which are not fused in this 10 mos old.
Q: What are you concerned about in this non-ambulatory patient with acute on chronic SDH. A: Child abuse

35. 40 yo male, s/p fall down stairs
Q: In which compartment do we see hemorrhage? A: There is SAH in the sylvian fissure b/l and left ambient cistern (left image), left frontal sulci (right image); the findings here are compatible with traumatic SAH. I would not expect students to precisely identify all locations but rather that this is SAH. They may think sylvian hemorrhage is contusion and I think that is OK given that we only showing one image through this region. This slide is to help the understand question on next slide.

36. 59 yo female, driver in MVC
This patient too came in with history of trauma, which occurred after MVA.
Q: What are the findings? A: Diffuse SAH. Lateral ventricles are dilated.
Q: Is this diffuse pattern of large amount of SAH, typical of traumatic SAH? A: No, this would make you concerned that the SAH preceded the trauma. Futher work up would be obtained with CT angiography to look for aneurysm which has ruptured.

37. Normal Cervical Spine Alignment
Q: What are the spinal lines we use to assess alignment? A: Anterior vertebral line; posterior vertebral line; spinolaminar line; posterior spinous line. Draw these on ipad with students. 1st image is midline CT and 2nd image is parasagittal CT so can look at alignment of articular pillars.

38. anterior vertebral line posterior spinous line
spinolaminar line
anterior vertebral line
posterior spinous line
Labelled image
posterior vertebral line

39. Would you image this patient?
35 yo female, s/p bicycle collision with posterior midline cervical tenderness
Would you image this patient?
Q: Would you image this patient? A: Yes. This patient has c/o of posterior midline cervical tenderness after trauma. She would most likely have a CT of the cervical spine but before discussing which study, move on to next slide.

40. What guidelines exist to help clinicians determine if patients who experience trauma should have C-spine imaging?
Use this slide to discuss NEXUS criteria. Q: What guidelines exist to help clinicians make these decisions for patients who experience trauma? A: Two sets of clinical decision rules serve as guidelines for determination if patients should have imaging of the cervical spine in the setting of blunt trauma. Those rules are NEXUS (North American Emergency X-Ray Utilization Study) and Canadian C-Spine rules. There is no consensus as to which rules should be used and it should be noted that many clinicians use a combination of the NEXUS criteria and Canadian C-spine rules to guide their decision process. However many find NEXUS easier to remember and apply. The Canadian C-spine criteria take mechanism of injury into consideration.

41. Nexus Criteria
C-spine imaging in all patients with neck trauma unless of these criteria are met:
No posterior midline cervical tenderness
No evidence of intoxication
Normal level of alertness (GCS=15)
No focal neurologic deficit
No painful distracting injury
If patient who has experienced blunt trauma, meets all five of these Nexus criteria, she may be classified as having low probability of injury. When these guidelines were established they were used to determine which patients should have radiography. However, radiography has largely been replaced by CT due to its high sensitivity (98.1%), specificity (98.8%) and negative predictive value (99.7%) which justify increased cost and XRT compared with radiography. In general, radiography is now reserved for patients who are considered low risk and thus meet all 5 of the NEXUS criteria or not done at all at many institutions. X-table lateral, however, may be included in the initial trauma series which consists of: AP chest, AP pelvis and X-table lateral of c-spine radiographs.

42. What should be done if this patient complains of upper extremity numbness and tingling?
Q: What would you do if this patient complains of upper extremity numbness and tingling? A: MRI. The presence of these neurologic deficits make you concerned that there has been injury to the cord and thus MRI should be obtained. CT cannot be used to evaluate the cord. We need the superior soft tissue contrast resolution provided by MRI to evaluate the cord.

43. 27 yo male, s/p low speed rear end collision, GCS = 15
Would you image this patient?
Q: Would you image this patient? What additional information do you want to know before making that decision. A: First, we must ask a few questions: Are there positive findings on physical exam? any midline cervical tenderness on exam? Any painful distracting injury? Is the patient intoxicated? Instructor should answer “no” to all of these questions. Thus, patient does meet all of the NEXUS criteria and CT imaging of his spine is not indicated.

44. 36 yo male s/p fall down flight of steps while intoxicated, +LOC
X-table lateral
Images courtesy of Jeff Hogg, MD
Q: What level is fracture at? What spinal lines are disrupted? A: Anterior and posterior vertebral lines disrupted, spinolaminar and posterior spinous lines disrupted. Fracture is at C7.

45. 36 yo male s/p fall down flight of steps while intoxicated, +LOC
X-table lateral
Images courtesy of Jeff Hogg, MD
Q: This patient was imaged with CT of the cervical spine. What features guided that decision? A: Patient is intoxicated. He experienced loss of consciousness. In addition, the mechanism here of falling down a flight of steps (any fall greater that 3 feet or 5 steps) is considered a dangerous mechanism that warrants imaging. These are part of Canadian C spine criteria which we will not expect students to know. However, we can emphasize that that mechanism plays a big role in the Canadian C-spine criteria and that most clinicians use combination of the NEXUS and Canadian C-spine rules, to guide their decision on when to image the cervical spine in the setting of blunt trauma
What features guided the decision to obtain a CT of the cervical spine?

46. 36 yo male s/p fall down flight of steps while intoxicated, +LOC
X-table lateral
Images courtesy of Jeff Hogg, MD
Q: Can you name other mechanisms of injury considered dangerous by Canadian C spine rules? A: Axial load to head (diving), MVA which is high speed (>60 mph), rollover or ejection; motorized recreational vehicles; bicycle collision.
Can you name other mechanisms which are considered high risk by the Canadian C spine rules?

47. 36 yo male s/p fall down flight of steps while intoxicated, +LOC
Images courtesy of Jeff Hogg, MD
This is same patient, axial bone window from C7 level. Q: This patient then went on to have CT angiography. Can you explain why CT angiography was ordered? A: the patient has a b/l facet dislocation; this makes patient make patient at high risk for arterial injury.. At the levels of C6 and above, fracture extending to the transverse foramen would also put the patient at high risk for arterial injury because the vertebral artery courses through it. CT angiography is used to make sure that the integrity of the vessels are maintained. Trauma can result in rupture, transection, dissection, thrombosis, pseudoaneurysm.
There are criteria which are used in blunt cerebrovascular criteria (BCVI) called the Denver criteria and discussion of these is beyond the scope of this workshop. However, risk of arterial injury has been found to be highest in patients with cervical interfacetal subluxation/dislocations and patients who have fractures which extend to the transverse foramen or ICA canal.
Can you explain why CT angiography was ordered on this patient?

48. Q: Can you name the two different studies here
Q: Can you name the two different studies here? A: (Left to right) Midline sagittal CT C-spine, bone window; parasagittal CT C-spine, bone window; lateral radiograph of C-spine.
Q: What are the alignment abnormalities and at what level? A: The anterior vertebral, posterior vertebral, spinolaminar and posterior spinous lines are ALL disrupted. On the parasagittal image, you can see that the alignment of the articular pillars/facets is disrupted.

49. What type of injury do you think this patient experienced?
Q: What type of injury do you think this patient experienced (hyperflexion, hyperextension, axial loading). A: Hyperflexion injury. This is most commonly seen in setting of whiplash.
What type of injury do you think this patient experienced?

50. Here is the MRI in the same patient
Here is the MRI in the same patient. Q: Why would MRI be indicated in this patient? A: If there are neurologic deficits, then MRI is indicated to look at the cord. This patient is likely to have neurologic deficits due to the obvious mass effect seen on the cord. However, we do not expect students to describe those findings. What students should know is that MRI has superior soft tissue contrast resolution and thus always preferred to evaluate the cord and ligaments.