Podcast
Questions and Answers
What is the primary goal of imaging in a patient with acute stroke?
What is the primary goal of imaging in a patient with acute stroke?
Which of the following is an early CT sign of ischemia?
Which of the following is an early CT sign of ischemia?
What does the Insular Ribbon sign indicate on a CT scan?
What does the Insular Ribbon sign indicate on a CT scan?
Why do we observe ischemia on a CT scan?
Why do we observe ischemia on a CT scan?
Signup and view all the answers
What does the Dense MCA sign suggest in a CT angiography?
What does the Dense MCA sign suggest in a CT angiography?
Signup and view all the answers
What percentage of MCA infarcts are initially hemorrhagic?
What percentage of MCA infarcts are initially hemorrhagic?
Signup and view all the answers
What correlates with the decrease in CT attenuation when brain water content increases?
What correlates with the decrease in CT attenuation when brain water content increases?
Signup and view all the answers
What can be seen as a result of inadequate ATP supply in the brain?
What can be seen as a result of inadequate ATP supply in the brain?
Signup and view all the answers
What is the most common cause of traumatic intracranial hemorrhage?
What is the most common cause of traumatic intracranial hemorrhage?
Signup and view all the answers
Which type of intracranial hemorrhage occurs most commonly from rupture of an aneurysm?
Which type of intracranial hemorrhage occurs most commonly from rupture of an aneurysm?
Signup and view all the answers
What is a primary complication of traumatic intracranial hemorrhage?
What is a primary complication of traumatic intracranial hemorrhage?
Signup and view all the answers
What anatomical structure separates the dura mater from the skull?
What anatomical structure separates the dura mater from the skull?
Signup and view all the answers
Which layer of the meninges allows blood vessels to nourish the brain?
Which layer of the meninges allows blood vessels to nourish the brain?
Signup and view all the answers
In patients on anticoagulant therapy, which type of hematoma is most likely to occur?
In patients on anticoagulant therapy, which type of hematoma is most likely to occur?
Signup and view all the answers
What type of injury is characterized by diffuse axonal injury (DAI)?
What type of injury is characterized by diffuse axonal injury (DAI)?
Signup and view all the answers
Which of the following describes an epidural hematoma?
Which of the following describes an epidural hematoma?
Signup and view all the answers
What is the primary cause of an epidural hematoma?
What is the primary cause of an epidural hematoma?
Signup and view all the answers
How does a subdural hematoma typically present in terms of location?
How does a subdural hematoma typically present in terms of location?
Signup and view all the answers
Which population is most commonly associated with subdural hematomas?
Which population is most commonly associated with subdural hematomas?
Signup and view all the answers
What differentiates an acute subdural hematoma's appearance from a chronic one?
What differentiates an acute subdural hematoma's appearance from a chronic one?
Signup and view all the answers
In which scenario is a subdural hematoma most likely to be detected as isodense?
In which scenario is a subdural hematoma most likely to be detected as isodense?
Signup and view all the answers
What characteristic is common to both hyperacute and rebleeding subdural hematomas?
What characteristic is common to both hyperacute and rebleeding subdural hematomas?
Signup and view all the answers
Why is an epidural hematoma more likely to cross the midline than a subdural hematoma?
Why is an epidural hematoma more likely to cross the midline than a subdural hematoma?
Signup and view all the answers
What is a typical sign of active bleeding in an acute subdural hematoma?
What is a typical sign of active bleeding in an acute subdural hematoma?
Signup and view all the answers
Study Notes
Computed Tomography (CT) Head Scan
- Prepared by Ahmed Jasem Abass, MSC Medical
Imaging in Acute Stroke
- Goal of imaging in acute stroke is to exclude hemorrhage
- Differentiate between irreversibly affected brain tissue and reversibly impaired tissue
- Identify stenosis or occlusion of major intracranial arteries
CT Early Signs of Ischemia
- Hypo-attenuating brain tissue
- Obscuration of the lentiform nucleus
- Insular Ribbon sign
- Dense MCA sign
- Hemorrhagic infarcts
Hypo Attenuating Brain Tissue
- Ischemia causes cytotoxic edema due to ion pump failure, requiring ATP
- 1% increase in brain water content results in a 2.5 HU decrease in CT attenuation
- Diagnosis of infarction is based on MCA location and involvement of gray and white matter
Obscuration of the Lentiform Nucleus
- Blurred basal ganglia, an important sign of infarction
- Seen in middle cerebral artery (MCA) infarction
- One of the earliest and most frequent signs
Insular Ribbon Sign
- Refers to hypodensity and swelling of the insular cortex
- A subtle early CT sign of infarction in the middle cerebral artery territory
- Sensitive to ischemia due to being furthest from collateral flow
- Differentiate from herpes encephalitis
Dense MCA Sign
- Result of thrombus or embolus in the MCA
- Visible on CT angiography as MCA occlusion
Hemorrhagic Infarcts
- 15% of MCA infarcts are initially hemorrhagic
- Hemorrhage easily detected with CT, also visualized with gradient echo MR sequences
Traumatic Intracranial Hemorrhage
- Any bleeding inside the skull or brain is a medical emergency
- Common causes include stroke, trauma, and ruptured aneurysms
- Complications include increased intracerebral pressure, edema, and hydrocephalus
Localization of Hemorrhage
- Subarachnoid Hemorrhage: Acute bleeding under the arachnoid membrane, often due to aneurysm rupture
- Subdural Hematoma: Bleeding between the dura and arachnoid membranes, usually from bridging vein rupture, common in elderly and patients on anticoagulants
- Epidural Hematoma: Bleeding between the dura and skull, often due to temporal bone fracture and middle meningeal artery rupture
- Intra-axial Hemorrhage (Intracerebral): Cerebral hemorrhagic contusion, post-traumatic small hemorrhages located near the skull, often frontobasal and anterior in temporal lobes
- Diffuse Axonal Injury (DAI): Diffuse injury at the gray-white matter junction, seen in high-velocity injuries and low sensitivity for CT, better seen on MRI.
Anatomy of the Meninges
- Meninges are three membranes (dura, arachnoid, and pia) enveloping brain and spinal cord
- Cerebrospinal fluid (CSF) is found in the subarachnoid space between arachnoid and pia
- Dura mater is the outermost meningeal layer, with two layers (inner and outer)
- Arachnoid mater is the delicate layer with fibers extending to pia
- Pia mater is the innermost layer, allowing nutrient blood vessels to pass through the brain
Traumatic Hemorrhage (Epidural Hematoma)
- Bleeding between dura and skull
- Common in children with head injury and temporal bone fractures, leading to tearing of the middle meningeal artery
- Usually does not cross suture lines.
Subdural Hematoma
- Collection of blood between inner dura and arachnoid membranes
- Cannot cross the midline
- Usually due to cortical bridging vein rupture, especially in elderly and alcoholics with atrophy
- Venous structures are less packed, increasing space for rupture.
Subdural Hematoma (CT Findings)
- Acute: High-density, hyperdense
- Chronic: Low-density, hypodensity.
- Midline shift seen on CT (left image example given)
The Images Show a Subdural Hematoma
- Hematoma displays both hyperdense and isodense areas (indicative of both acute and chronic bleeding).
- Displacement of midline structures and CSF flow obstruction (dilated temporal horn of the right lateral ventricle).
- Acute: Hyperdense (clotted blood); Subacute: Isodense; Chronic: Hypodense (relative to brain parenchyma)
- Heterogeneous appearance in acute setting due to combination of both fresh and clotted blood.
Isodense Subdural Hematoma
- Aging hematomas decrease in density, matching that of the brain, making them harder to detect on CT.
- Can be bilateral.
- Rare case appearance: isodense to brain tissue; e.g., in patients with severe anemia, disseminated intravascular coagulation, or dilution with CSF.
Chronic Subdural Hematoma
- Appears hypodensity to parenchyma and isodensity to CSF after 21 days
- Can mimic a hygroma
- Hygroma is due to traumatic tear in the arachnoid layer that causes CSF leak into the subdural space
Subarachnoid Hemorrhage
- Hyperdense blood in the subarachnoid space (Sylvian fissure).
- Can have subgaleal hemorrhage in the occipital region.
- Often due to coupe contrecoup type injuries (double impact trauma)
Coupe Contrecoup Type of Injury
- Characterized by contusional hemorrhages, subdural hematoma, and subarachnoid hemorrhage on opposite side of the impact site.
- Often associated with parietal bone fracture and subarachnoid hemorrhage.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers essential aspects of computed tomography (CT) imaging in acute stroke cases. Focused on identifying early signs of ischemia and differentiating between types of brain tissue, the quiz also explores specific signs like the Insular Ribbon and the importance of detecting major intracranial artery occlusions. Enhance your understanding of CT's role in stroke diagnosis and management.
