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Clincal Quiz
CASES IN NEURORADIOLOGY
Jason Martin1
Michael G. DeGroote School of Medicine, McMaster University,
1
Hamilton, Ontario, Canada
Author for Correspondence:
Jason Martin
Michael G. DeGroote School of Medicine, McMaster University,
1280 Main Street West, MDCL 3010, Hamilton, ON L8S 4L8
Email: jason.martin@medportal.ca
Conflict of Interest:
The authors have no conflicts of interest to disclose.
CASE 1
A
CASE 2
67 year-old woman presents to the emergency
department with loss of consciousness. The patient’s
daughter mentions that her mother lost consciousness
hours after hitting her head on her car door while exiting
the vehicle. She has a past medical history of atrial
fibrillation, diabetes type II, remote myocardial infarction, hypertension
and dyslipidemia. She is currently taking Aspirin, Warfarin and Insulin.
The emergency physician ordered a non-contrast axial computed
tomography (CT) scan, shown below (Figure 1).
Paramedics brought a 20 year-old female in to the hospital after a
motorcycle accident. Upon examination, the patient is found to
have a fractured right humerus and left femur. Glasgow Coma Scale
(GCS) was four. The accident report describes a high-speed impact
with the patient being ejected from the vehicle during the collision.
The patient was not wearing a helmet. CT angiography was ordered
by the emergency physician, shown below (Figure 2). There is no
past medical history. Patient is currently taking the Alysena oral
contraceptive pill.
Figure 1. Axial CT images in a 67 year-old woman with low-impact
head injury.
Figure 2. CT Angiogram (with IV contrast) of a 20 year-old female
involved in a motor vehicle accident (MVA). Sagittal (a)
and coronal (b) slices are shown.
What is the most likely diagnosis?
A. Contusion
B. Subdural Hematoma
C. Epidural Hematoma
D. Subarachnoid Hemorrhage
The above process can best be described as:
The patient’s imaging is least consistent with which of
the following diagnoses?
A. Dissection
B. Carotid Embolism
C. Brain Death
D. All would be on your differential
A. Acute
B. Subacute
C. Chronic
D. None of the above
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Cerebral angiography (Figure 3) was performed to confirm the
diagnosis.
This entity can occur via genetic mutations.
True
False
What type of pathology is this?
A. Sporadic
B. Acquired
C. Familial
Figure 3. Catheter cerebral angiography of Internal Carotid Artery
(ICA) with radiopaque dye.
ANSWERS
What is the most likely diagnosis?
CASE 1
A. Dissection
B. Carotid Embolism
C. Brain Death
Answers: B, C
CASE 3
A 73 year-old female presents to her family doctor with rapidly
progressive dementia. Over the past few weeks, the patient has
experienced increasing memory loss, hallucinations, ataxia, unsteady
gait, seizures and myoclonus. She has no past medical history. She is on
no medication currently. Her family physician orders an urgent MRI to
elucidate the cause of her symptoms, shown below (Figure 4).
Figure 1. Axial CT images in a 67 year-old woman with low-impact
head injury. Arrows reveal a subural hematoma in the
left fronto-parietial region.
Explanation
Figure 4. Axial MR images of a 53 year-old woman with rapidly
progressing dementia. Diffusion weighted imaging (DWI)
(a) and T2 (b) images are shown here.
What is the likely diagnosis?
A. Leigh Syndrome
B. Osmotic Demyelination Syndrome
C. Wilson Disease
D. Hypoxic Ischemic Injury
E. Creutzfeld-Jakob Disease
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A subdural hematoma is the most likely diagnosis for this patient’s
condition, and is characterized by an extra-axial, crescent-shaped
hematoma (blue arrows in Figure 1). The patient’s age (>60 years)
makes a subdural hematoma more likely as the dura is more
tightly adhered to the skull in this population. The hematoma
is hypodense relative to cortex, suggesting a chronic bleed. The
anticoagulation status of the patient should increase the clinician’s
suspicion for a vascular disruption. Acute hematomas in most
patients consist primarily of coagulated blood, which is hyperdense
relative to brain parenchyma on CT. Over time, resorption of the
clot and neovascularization results in increasing isodensity and, later,
hypodensity of the hematoma, assuming re-bleeding does not occur.
Etiology
Subdural Hematoma (SH) - Subdural hematomas are typically caused
by tearing of the bridging cortical veins as they cross the subdural
space,1 usually secondary to shearing forces resulting from a sudden
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change in cranial velocity. The arachnoid may also be torn, creating
a mixture of blood and CSF in the subdural space.1 Figure 5 outlines
the basic anatomy of the skull and meninges.
spontaneous acute subdural hematomas are associated with an
underlying abnormality that may precipitate hemorrhage, such as
dural arteriovenous fistulas or cerebral tumors.
Epidural Hematoma (EH) – Trauma to the sphenoid resulting in
rupture of the middle meningeal artery is the most common etiology
for epidural hematomas, although the anterior meningeal artery
is infrequently involved. An associated skull fracture is present in
approximately 80% of cases.1 Epidural hematomas can often be
homogenous, and chronic, hypodense epidural hematomas are also
seen. Associated pain results from shearing of the dura from bone.1.
The increased incidence of epidural hematomas in younger patients
is not only a function of the increased incidence of head injury in
that population, but also related to the dural structure.1 In younger
patients, the Dura is less tightly attached to the skull, creating a
favourable environment for hematoma formation.
Epidural Hematoma - Epidural hemorrhages are most often
precipitated by a blunt force impact with or without loss of
consciousness. Patients with an initial “lucid” interval may suffer
rapidly deteriorating neurological status with severe headache and
progressive loss of consciousness. Other symptoms of elevated
intracranial pressure (ICP) are the result of mass effect, and include
nausea, vomiting, headache and visual disturbances. Cushing’s triad
can be seen in elevated ICP, and involves an increased systolic blood
pressure, bradycardia, and an abnormal respiratory pattern. If elevated
ICP progresses without intervention, it may lead to death.
Subarachnoid Hemorrhage (SAH) – In 85% of cases of spontaneous
SAH, the cause is rupture of a cerebral aneurysm—a weakness in an
arterial wall (specifically, the medial layer) that becomes enlarged. They
tend to be localized at bifurcation points in the circle of Willis and its
branches. While most cases of SAH are due to bleeding from small
aneurysms, larger aneurysms are more likely to rupture.2 An initial
angiogram may fail to detect an aneurysm in 15–20% of spontaneous
SAH.3 Half of these undetected cases are a result of non-aneurysmal
perimesencephalic hemorrhages, in which blood is limited to the
subarachnoid spaces within the midbrain. The source of bleeding
in these cases is uncertain.2 Other common causes of spontaneous
SAH include arteriovenous malformations, vasculopathies, and
hemorrhagic neoplasms.2 Less frequently, SAH may result from
cocaine abuse, sickle cell anemia, anticoagulant therapy, and pituitary
apoplexy.3,4
Subarachnoid Hemorrhage - Patients characteristically present with
a thunderclap headache, often reported by patients as the worst
headache of their lives. Photophobia is common, which overlaps with
the presentation of meningitis. Consciousness may be lost acutely in
up to 50% of patients.5.
Imaging
Epidural Hematoma – on CT, EH are typically bi-convex or lentiform
in shape, and most frequently occur beneath the squamous aspect
of the temporal bone (Figure 7a). They are hyperdense, somewhat
heterogenous, and sharply demarcated. Depending on their size,
secondary features of mass effect (e.g. midline shift, subfalcine
herniation, uncal herniation) may be present.1
Subdural Hematoma generally presents as a crescent-shaped, extraaxial, multi-septated collection of fluid on CT. Over 85% are
unilateral1. SDHs do not respect suture lines, but are limited by
dural reflections, such as the falx cerebri, tentorium, and falx cerebelli.
Ascertaining the temporal sequence (timing) of the bleed is aided by
examining the density of the hematoma on a non-contrast enhanced
CT (Figure 6).
Time After Injury Appearance on CT
Acute
Figure 5. Layers of the skull and meninges.
< 72 Hours
Hyperdense
Subacute
3-7 Days
Isodense or Hypodense
Chronic
> 3 Weeks
Hypodense, but may be
mixed when rebleeding
has occurred
Clinical History
Subdural Hematoma– Acute subdural hematomas usually present in
the setting of head trauma. This is especially the case in young patients,
where they commonly present in addition to cerebral contusions.
Most patients present with decreased level of consciousness, with
abnormal pupillary response in 30 - 50% of cases.1 Occasionally,
Figure 6. Relationship of timing of bleed and CT attenuation
characteristics.
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Subarachnoid Hemorrhage - The sensitivity of CT to the presence
of subarachnoid blood is strongly influenced by both the amount
of blood and time of onset. The diagnosis is suspected when
hyperattenuating collections infiltrate the subarachnoid space. Most
commonly this is adjacent to the circle of Willis, largely because
the majority of berry aneurysms form in this region (~65%), or in
the sylvian fissure (~30%).1 Small amounts of blood can sometimes
be appreciated pooling in the interpeduncular fossa, appearing as a
small hyperdense triangle, or within the occipital horns of the lateral
ventricles.
Figure 2. CT Angiogram (with IV contrast) of a 20 year-old female
in a MVA. Sagittal (a) and coronal (b) slices are shown.
(c) Noncontrast CT, axial view. Arrows reveal lack of
perfusion within the internal carotid artery.
Brain Death - Imaging
General radiologic features include sulcal and gyral effacement,
ventricle effacement and compression.6
Figure 7. Spectrum of vascular and parenchymal involvement
in head trauma. Epidural hematoma (a), subdural
hematoma (b) and subarachnoid hemorrhage (c) are
shown here.
The need for radiological characterization and diagnosis affects
treatment choices for the patient in both the acute and chronic
setting. With the history of head trauma, the need for surgical
evacuation in EH is often more time-sensitive in SDH or SAH. With
timely recognition and intervention, patient morbidity and mortality
may be improved.
CASE 2
Answers: D, C
CT – Look for diffuse edema, swollen gyri and compressed cisterns &
ventricles, and no enhancement of vasculature with contrast.
MRI - T1 reveals hypointense loss of grey-white matter differentiation.
Brain herniation may be present.
T2: Reveals hyperintense cortex and swollen gyri.
MR Angiography: May show minimal or absence of intracranial flow.
A secondary sign known as the “hot nose” of brain death can be seen
on scintigraphic brain flow scans (Figure 8).7 The hot nose sign may
be seen in patients who have diminished blood flow in one or both
internal carotid arteries.7 Decreased internal carotid blood flow leads
to increased or collateral flow through the external carotid artery on
the involved side, producing markedly increased perfusion to the
nasal region.7
Explanation
Given the history of a high-grade head impact and the appearance
of a smoothly tapered internal carotid artery with absence of intracerebral perfusion on CT angiogram, this patient’s imaging is
consistent with brain death.
Brain Death - Pathophysiology
Brain death is the culmination of severe cellular and extracellular
edema in the context of raised intracranial pressure (ICP).1 Markedly
elevated ICP causes low cerebral blood flow. If ICP is higher than
end-diastolic pressure, retrograde flow occurs.1 If ICP is higher than
systolic pressure, cessation of blood flow occurs, leading to complete
and irreversible loss of brain function.1
In the majority of instances, clinical diagnosis suffices in classifying a
patient as brain dead. Conformation is usually performed with CTA,
MRA or cerebral angiography. However, before the diagnosis is even
confirmed, preliminary CT or MR studies may reveal characteristic
changes, especially when ordered in the setting of trauma.
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Figure 8. Hot Nose Sign.
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CASE IN NEURORADIOLOGY
In this current case, both carotid dissection and embolism would
remain on the differential.
A. Dissection – a possibility, albeit the odds of bilateral internal carotid
dissection are low. A history of trauma should raise suspicion for
dissection, but the angiographic appearance is quite different, often
demonstrating abnormal vessel contour, a visible psuedoaneurysm,
or the string sign, a thin stripe of flow caused by decreased pressure
distal to the stenosis1.
B. Carotid Embolism – A valid diagnostic consideration, but again
the odds of a concomitant embolism in the same section bilaterally
are very low. Embolic lesions also typically present with an abrupt
tapering of the occluded vessel, with clinical signs of infarction to the
non-perfused brain region.
CASE 3
Answers: E, FALSE, A
Explanation
There is considerable overlap in presentation between the listed
differential. However, a characteristic feature in this patient provides
a clue to diagnosis.
In this case, the T1 hyperintensity of the globus pallidus suggest
sporadic CJD, and the T2 hyperintense basal ganglia and thalami on
MRI further support the diagnosis of CJD. These findings, combined
with the clinical picture of rapidly progressing dementia in a middleaged female make CJD the likely diagnosis.
Pathophysiology
Creutzfeldt–Jakob disease (CJD) is a degenerative neurological
disorder that is incurable and lethal. It is the most common form
of the human spongiform encephalopathies. CJD results from
accumulation of misfolded versions of the prion protein encoded
by the prion protein (PrP) gene on chromosome 20. In CJD, the
brain tissue atrophies, creating holes and taking on a sponge-like
appearance. Gross cerebral atrophy may result1. Prions are misfolded
proteins, which propagate by converting their properly folded
versions.
Acquired CJD is better encapsulated by the terms PrPi (Iatrogenic) and
variant CJD (vCJD). vCJD is thought to be caused by consumption
of food contaminated with prions. Iatrogenic CJD arises from
contamination from an infected person, classically associated with
human-derived pituitary growth hormone, corneal and/or meningeal
transplants. CJD can also be acquired via introduction of prions into
healthy cells (1% of cases), or sporadically from mutations of the
normal host-encoded protein (85% of cases). 1
Figure 4. Axial MR images of a 53 year-old woman with rapidly
progressing dementia. Diffusion weighted imaging
(DWI) (a) and T2 (b) images are shown here. Arrows
reveal DWI hyperintensity of the globus pallidus and T2
hyperintensity of the basal ganglia and thalami.
Imaging
CT – Usually normal, but may show progressive atrophy and
ventricular dilatation.
MR – T1 – Caudate or globus pallidus hyperintensity may be
reported in sporadic CJD.
T2 – Hyperintense basal ganglia and thalami may be seen, as well as
hyperintense cortical grey matter and atrophy.
FLAIR – The pulvinar sign suggests CJD: Bilateral symmetrical
hyperintensity of pulvinar (posterior) nuclei of thalamus relative to
anterior putamen. The hockey stick sign shows symmetrical pulvinar
and dorsomedial thalamic nuclear hyperintensity, characteristic of
variant CJD.
A. Leigh Syndrome - Leigh disease is one of many mitochondrial
disorders, due to a wide variety of possible genetic mutations in
mitochondrial DNA (mtDNA). As with any mitochondrial disorder,
it is only inherited from the mother. Leigh Syndrome primarily
presents in children, with psychomotor delay and superimposed signs
of basal ganglia and brainstem dysfunction (ataxia, ophthalmoplegia,
dystonia, cranial nerve palsies).8
B. Osmotic Demyelination Syndrome - acute demyelination of
the white matter tracts traversing the pons. It seen in the setting of
osmotic changes, typically with rapid correction of hyponatraemia.
Lesions are hyperintense on T2 sequence MRI imaging, most often
in the putamen and external capsule.
C. Wilson Disease (WD) – is a disorder that results from abnormal
ceruloplasmin metabolism secondary to mutations in the ATP7B
gene located on chromosome 13q14.3. This gene product is a cation
transport ATPase, functioning to export copper out of cells. When
mutated, the dysfunctional gene product leads to total body copper
elevation, with deposition and resultant damage to a variety of organs,
notably the liver and brain. If copper predominates, affected organs
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are T1 hyperintense and T2 hypointense. If gliosis predominates
organs are T1 hypointense, T2 hyperintense.9
D. Hypoxic-Ischemic Injury - Severe global hypoxic-ischemic injury
in this population primarily affects the gray matter structures.10 This
predominance of gray matter injury is related to the fact that gray
matter contains most of the dendrites where postsynaptic glutamate
receptors are located. They are therefore the sites most susceptible to
the effects of glutamate excitotoxicity.10 Due to synaptic activity, gray
matter is also more metabolically active than white matter. Cerebellar
injury can be seen in neonates, but it tends to be more common in
older patients.10 The reason for this is not known, but one theory
is that the relative immaturity of Purkinje cells (which are normally
very sensitive to ischemic damage) in neonates somehow protects the
cerebellar cortex.10
References
1. David M. Yousem. Robert D. Zimmerman, and Robert I.
Neuroradiology: The Requisites. Grossman Philadelphia, Pa:
Mosby, 2010. ISBN 978-0-323-04521-6.
2. v
an Gijn J, Kerr RS, Rinkel GJ (2007). “Subarachnoid
haemorrhage”. Lancet 369 (9558): 306–18.
3. Rinkel GJ, van Gijn J, Wijdicks EF (1 September 1993).
“Subarachnoid hemorrhage without detectable aneurysm. A
review of the causes” (PDF). Stroke 24 (9): 1403–9.
4. Warrell, David A; Timothy M. Cox, et al. (2003). Oxford Textbook of
Medicine, Fourth Edition, Volume 3. Oxford. pp. 1032–1034. ISBN
0-19-857013-9.
5. Van gijn J, Rinkel GJ. Subarachnoid haemorrhage: diagnosis,
causes and management. Brain. 2001;124: 249-78.
6. Brain death: Diagnostic clues on imaging. J Emerg Trauma Shock.
2012 Oct-Dec; 5(4): 372–373.
7. Huang AH. The hot nose sign. Radiology. 2005;235 (1): 216-7.
8. Arii J, Tanabe Y. Leigh syndrome: serial MR imaging and clinical
follow-up. AJNR Am J Neuroradiol. 2000;21 (8): 1502-9.
9. Hegde AN, Mohan S, Lath N et-al. Differential diagnosis for
bilateral abnormalities of the basal ganglia and thalamus.
Radiographics. 31 (1): 5-30.
10. Huang BY, Castillo M. Hypoxic-ischemic brain injury: imaging
findings from birth to adulthood. Radiographics. 28 (2): 417-39.
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