Neuroradiology Flashcards
Head CT interpretation
-What is the orientation of a head CT?
view from the patient’s feet to the head
-Left side of the image is the right side of the patient
When is contrast used in a head CT?
Contrast cannot cross the BBB
-Contrast is used if there is suspicion of tumor, infection, or vascular abnormality
Head CT interpretation pneumonic?
Blood-Blood Can-Cisterns Be-Brain Very-Ventricles Bad-Bad
What is the appearance of an acute hemorrhage on head CT?
Acute hemorrhage-hyperdense (white)
What is the appearance of a chronic hemorrhage on head CT?
Chronic hemorrhage-hypodense
Head CT-cisterns
Assess for symmetry, collection of blood
Head CT-brain
-Symmetry, gray-white differentiation, shift, hypo/hyperdensities
Head CT-ventricles
-Asymmetry, dilation, effacement, hemorrhage
Head CT-bone
- Bone windows
- Fractures, tumors
Skull fractures patients can present with?
- CSF rhinorrhea
- Otorrhea
- Battle’s sign
- Raccoon eyes
- Neurologic signs
With open/depressed skull fractures there is an increased risk of?
infection/meningitis due to breached dura
What is the modality of choice for evaluating skull fractures?
Non-contrast CT
- Examine bone and soft tissues
- Pneumocephalus or bleeding into paranasal sinuses
Skull anatomy
Cribriform plate
Cribriform plate-CN I
Optic canal
Optic canal-CN II, ophthalmic a
Superior orbital fissure
Superior orbital fissure-CN III, IV, V1, ophthalmic vein
Foramen rotundum
Foramen rotundum-V2
Foramen ovale
Foramen ovale-V3
Foramen spinousum
Foramen spinosum-Middle meningeal a
Foramen lacerum
Foramen lacerum-Internal carotid a
Internal auditory meatus
Internal auditory meatus-CN VII, VIII
Where does CN VII exit the skull?
CN VII exits the skull via the stylomastoid foramen
Jugular foramen
Jugular foramen-CN IX, CN X, CN XI, internal jugular vein
Hypoglossal canal
Hypoglossal canal-CN XII
Foramen magnum
Foramen magnum-Spinal cord, CN XI, vertebral aa
Blunt trauma to the eye can produce?
Blowout fractures
What are the characteristics of blowout fractures?
- Intraorbital pressure shatters the floor of the orbit (roof of the maxillary sinus)
- The bone separating the orbit from the maxillary sinus is thin
- Bleeding into the maxillary sinus can result in blood draining into the nasal cavity
Skull fractures-management considerations
-CT is used to assess?
- CT is used to assess status of underlying TBI
- Cervical spine assessment
- Neurosurgical consultation
CT is used to assess status of underlying TBI
- Intracranial hemorrhage
- Parenchymal injury (cerebral contusion)
- Type of fracture (linear, depressed, basilar)
- Angiography to assess artery supply (basilar, petrous portion of temporal bone)
Herniation syndromes
Displacement of brain tissue past the rigid dural folds or through openings of the skull
-Increased intracranial pressure (compression of vasculature)
Due to mass effect
-Global (generalized edema)
-Focal (tumors, abscesses, hemorrhages)
3 types of herniation syndromes?
- Cingulate (subfalcine)
- Uncinate (transtentorial)
- Tonsillar herniation
Cingulate (subfalcine) herniation
- Herniation beneath falx cerebri
- Can compress anterior cerebral artery
What are the signs/symptoms associated with cingulate (subfalcine) herniation?
- Paraparesis
- Urinary incontinence
- Frontal release signs (primitive reflexes)
Uncinate (transtentorial) herniation
- Medial aspect of the temporal lobe compressed against free tentorium
- Oculomotor nerve
- Posterior cerebral a
- Compression of Kernohan notch
- Duret hemorrhages in midbrain and pons
Impingement of the oculomotor nerve by an uncinate hemorrhage results in?
Impingement of the oculomotor nerve by an uncinate hemorrhage results in fixed dilation and impairment of ocular movements
Compression of the posterior cerebral artery by an uncinate hemorrhage results in?
contralateral homonymous hemianopsia
Compression of the Kernohan notch by an uncinate process results in?
ipsilateral limb weakness
Tonsillar herniation
- Displacement of cerebellar tonsils through foramen magnum
- Brainstem compression compromises respiratory and cardiac centers in medulla
What are the signs and symptoms associated with tonsillar herniation?
- Decreased level of consciousness
- Flaccid paralysis
- Blood pressure instability
What are the characteristics of a CT of a cingulate herniation?
CT of a cingulate herniation
- Midline shift of septum pellucidum
- Ventricle compression/dilation
What are the characteristics of an MRI of an uncal herniation?
- Displacement of uncus and medial temporal lobe
- Encroachment of suprasellar cistern
- Aquaduct compression -> increased lateral ventricle pressure
What are the characteristics of an epidural hematoma?
- Rupture of middle meningeal a (fx of temporal bone)
- Lucid interval
- Rapid expansion of epidural space under arterial pressure
- Herniation
- Biconvex (lens) shaped
- Does not cross suture lines
- Can cross falx, tentorium
What are the characteristics of a subdural hematoma?
- Rupture of bridging veins
- Slow venous bleeding
- Manifestation of symptoms within 48 hours
- Herniation/compression symptoms
- Crescent shaped
- Crosses suture lines
- Does not cross falx, tentorium
What are the characteristics of subarachnoid hemorrhage?
- Aneurysm rupture of cerebral a (saccular), arteriovenous malformation
- Ehlers-Danlos syndrome, ADPKD
- Rapid loss of consciousness
- “Worst headache of my life”
- Bloody or yellow lumbar puncture
- Intracerebral extension, subarachnoid blood in sulci on CT
What are common complications of subarachnoid hemorrhage?
Complications of subarachnoid hemorrhages
- Vascular spasm 2-3 days due to blood breakdown
- Rebleeding
Vascular spasm caused by subarachnoid hemorrhage should be treated with?
Tx vascular spasm caused by subarachnoid hemorrhage with Nimodipine-dilates vessels
What are the characteristics of intraparenchymal hemorrhage?
- Systemic HTN
- Amyloid angiopathy, vasculitis, neoplasm
- Mid-to-late adults
- Hyperdensity in basal ganglia, internal capsule on CT
- Ventricle infiltration, edema, herniation
- Sudden onset of neurological symptoms (stroke)
emorrhagic cerebrovascular disease/stroke
Hemorrhagic CVD/stroke
- Subarachnoid hemorrhage
- Intracerebral hemorrhage
Hemorrhagic cerebrovascular disease/stroke
-What are the characteristics of intracerebral hemorrhage?
- HTN, anticoagulation, cancer
- Basal ganglia = most common site
- Can occur secondary to ischemic stroke due to vessel fragility
Ischemic cerebrovascular disease/stroke
- Acute blockage of vessels
- Thrombotic
- Embolic
- Hypoxic
Thrombotic ischemic cerebrovascular disease/stroke
- Clot at site of infarction
- Atherosclerotic plaque
Embolic ischemic cerebrovascular disease/stroke
- Embolus from distant location obstructs vessel
- A-fib, DVT with patent foramen ovale
Hypoxic ischemic cerebrovascular disease/stroke
- Hypoperfusion or hypoxemia
- Watershed areas
MR angiography is used to detect?
occlusion or stenosis
-Images taken before contrast injection and during first pass of contrast through arteries
Anterior cerebral artery
- Paralysis of contralateral foot and leg
- Cortical sensory loss over toes, foot, and leg
- Urinary incontinence
- Impairment of gait and stance
Middle cerebral a
- Paralysis and sensory impairment of contralateral face and arm
- Motor aphasia
- Homonymous hemianopsia (optic radiation in temporal lobe)
- Hemineglect
Posterior cerebral artery
- Occipital cortex, visual cortex
- Homonymous hemianopsia with macular sparing (upper quadrant)
Lenticulo-striate artery
- Striatum, internal capsule
- Contralateral hemiparesis/hemiplegia (UMN)
- Corticospinal tract
Anterior spinal artery
- “Medial medullary syndrome”
- LCST, ML, CN 12
- Contralateral hemiparesis (UE and LE)
- Decreased contralateral proprioception
- Ipsilateral hypoglossal dysfunction
Posterior inferior cerebellar artery
- “Lateral medullary syndrome”
- Vestibular nuclei (vertigo, nystagmus)
- Spinothalamic tract/spinal trigeminal nucleus
- Nucleus ambiguus
- Sympathetics (ipsilateral Horner syndrome)
- Inferior cerebellar peduncle
PICA -> vestibular nuclei -> symptoms?
PICA -> vestibular nuclei -> symptoms -> Vertigo, nystagmus
PICA -> spinothalamic tract/spinal trigeminal nucleus -> symptoms?
PICA -> spinothalamic tract/spinal trigeminal nucleus -> symptoms -> decreased pain and temp sensation ipsilateral face, contralateral body
PICA -> nucleus ambiguus -> symptoms?
PICA -> nucleus ambiguus -> symptoms -> dysphagia, hoarseness, decreased gag reflex
PICA -> inferior cerebellar peduncle -> symptoms?
PICA -> inferior cerebellar peduncle -> symptoms -> ataxia, dysmetria
List all symptoms of PICA on previous cards
- Vertigo, nystagmus
- Decreased pain and temp sensation ipsilateral face, contralateral body
- Dysphagia, hoarseness, decreased gag reflex
- Ataxia, dysmetria
Anterior inferior cerebellar artery
- “Lateral pontine syndrome”
- Vestibular nuclei
- Facial nucleus
- Spinal trigeminal nucleus/spinothalamic tract
- Cochlear nuclei
- Middle and inferior cerebellar peduncles
AICA -> facial nucleus -> symptoms?
AICA -> facial nucleus -> symptoms -> paralysis of face, decreased lacrimation/salivation
AICA -> cochlear nuclei -> symptoms?
AICA -> cochlear nuclei -> symptoms -> deafness, tinnitus
Basilar artery
- “Locked in syndrome”
- Pons, medulla, lower midbrain
- Corticospinal/bulbar tracts
- Ocular cranial nerve nuclei
- Paramedian pontine reticular formation
What are the symptoms of “Locked in syndrome” (basilar a)?
- Preserved consciousness/blinking
- Quadriplegia
- Loss of voluntary facial, mouth, and tongue movements
CVD/stroke radiology
-Initial imaging?
- Initial imaging-non-contrast CT to exclude hemorrhage (tPA therapy)
- Hyperdensity
CVD/stroke radiology
-Detection of ischemic changes via CT?
CT detects ischemic changes in 6-24 hours
- Cortical hypodensity, parenchymal swelling
- Loss of grey-white matter differentiation
Diffusion weighted MRI can detect ischemia within?
Diffusion weighted MRI can detect ischemia within 3-30 mins
- diffusion of water molecules
- Increased ratio of intracellular to extracellular water volume in ischemic brain cells
CVD/stroke: global ischemia
- Hypoperfusion or hypoxemia states
- Drowning, cardiac arrest, cardiovascular surgery
- Hippocampus, watershed areas
- Difficulty forming new memories, acquiring new info
- Cortical blindness-weakness of shoulders, thighs with sparing of face, hands, feet
Watershed areas
-Anterior cortical border zone?
Anterior cortical border zone-Between ACA and MCA
Internal border zone?
Internal border zone-Between LCA and MCA
Posterior cortical border zone?
Posterior cortical border zone-between MCA and PCA
Multiple sclerosis
- AI inflammation and demyelination of the CNS
- HLA-D2 association
- Disease is initiated by Th1 and Th17 cells reacting against myelin
- Demyelination is caused by wbcs (Th17 cells)
Clinical presentation of multiple sclerosis?
- 20-30 y/o female
- Relapsing, remitting symptoms
- Unilateral optic neuritis
- Intranuclear ophthalmoplegia
- Hemiparesis
- Hemisensory symptoms
- Bladder, bowel incontinence
Multiple sclerosis diagnosis
-Increased IgG levels in CSF (oligoclonal bands are diagnostic)
Multiple sclerosis radiology
- MRI (gold standard)
- Periventricular plaques (oligodendrocyte loss, reactive gliosis)
- White matter lesions separated by space and time
Multiple sclerosis-internuclear ophthalmoplegia
-Lesion of what structure?
Internuclear ophthalmoplegia-> Lesion of MLF (highly myelinated to coordinate both eyes)
Multiple sclerosis
-Conjugate horizontal gaze palsy
Multiple sclerosis-Conjugate horizontal gaze palsy
- CN VI nucleus activates to abduct, contralateral CN III nucleus does not retract
- Opposite medial rectus does not fire, CN VI over-fires to stimulate CN III (nystagmus)
Adult brain tumors (MGM studios)
-Metastases
Metastases
- Most common CNS tumor
- Junction of gray and white matter, round shape
- Single or multiple
- Lung, breast, kidney, colorectal cancer, melanoma
Adult brain tumors (MGM studios)
-Glioblastoma multiforme (grade IV astrocytoma)
- Highly malignant - 1 year survival
- Cerebral hemispheres
- Can cross corpus collosum (butterfly glioma)
- GFAP+ astrocytes
- Pseudopalisading necrosis and hemorrhage
Adult brain tumors (MGM studios)
-Meningioma
Meningioma
- Typically benign
- Parasagittal region
- Arises from arachnoid cells, may have dural attachment
- Seizures or focal neuro signs
- Spindle cells concentrically arranged, psammoma bodies
Adult brain tumors (MGM studios)
-Schwannoma
- Cerebellopontine angle
- Schwann cell origin (S100+)
- Can be localized to CN VIII (vestibular schwannoma)
- Bilateral schwannomas found in NF2
Adult brain tumors
-Oligodendroglioma
Oligodendroglioma
- Slow-growing
- Frontal lobes
- “Chicken wire” capillary pattern
- Oligodendrocyte origin (fried-egg cells)-round nuclei with clear cytoplasm
Adult brain tumors
-Pituitary adenoma
Pituitary adenoma
- Slow-growing
- Commonly prolactinoma
- Bitemporal hemianopia (pressure on optic chiasm)
- Hyper or hypo pituitarism
Childhood brain tumors (“Animal Kingdom, Magic Kingdom, Epcot”)
-(Pilocytic) astrocytoma
(Pilocytic) astrocytoma
- Well circumscribed
- Posterior fossa (can be supratentorial)
- GFAP+
- Benign, good prognosis
- Rosenthal fibers (eosinophilic corkscrew fibers)
hildhood brain tumors (“Animal Kingdom, Magic Kingdom, Epcot”)
-Medulloblastoma
- Highly malignant
- Cerebellum (vermis)
- Primitive neuroectodermal tumor
- Can compress 4th ventricle-> hydrocephalus
- “Drop metastases” to spinal cord
- Homer-wright rosettes
Childhood brain tumors (“Animal Kingdom, Magic Kingdom, Epcot”)
-Ependymoma
Ependymoma
- Arise within or adjacent to ependymal lining of ventricular system (4th ventricle)
- Can cause hydrocephalus
- Perivascular rosettes
- Poor prognosis
Childhood brain tumors (“Animal Kingdom, Magic Kingdom, Epcot”)
-Craniopharyngioma
- Benign (can be confused with pituitary adenoma)
- Most common childhood supratentorial tumor
- Derived from Rathke pouch remnants
- Calcification common, oil-like fluid
Common brain infections
-Bacterial brain abscess
- Focal collection of necrosis and inflammation
- Local extension from adjacent foci, hematogenous spread
- Strep and staph most common in healthy patients
Signs and symptoms of bacterial brain abscess?
- Headache (not relieved with aspirin), neck stiffness, vomiting (increased ICP)
- Sinus infections, trauma, hematogenous spread (endocarditis, chronic pulmonary infections, rec. drug use)
Where are bacterial brain abscesses usually located?
distribution of the MCA
What modality is useful in differentiating ring-enhancing lesions due to bacterial infection vs neoplasm?
MRI (DWI) is capable of differentiating ring-enhancing lesions due to bacterial infection vs neoplasm
Common brain infections
-Mucor and Rhizopus spp.
- Fungi, proliferate in blood vessel walls, penetrate cribriform plate, and enter brain
- Frontal lobe abscess, cavernous sinus thrombosis
Signs and symtoms of mucor and rhizopus spp brain infection?
- Headache
- Facial pain
- Black Escher on face
- CN involvement (does not specify which one)
- DKA/neutropenic patients
Common brain infections
-Signs and symptoms of HSV1 brain infection?
Signs and symptoms of HSV1 brain infection
- Alterations in mood, behavior, memory
- Only 10% have prior hx of herpes infections
What effect does HSV1 infection have on brain tissue (pathology)?
HSV1 brain infection -> necrotizing and hemorrhagic (no abscess formation)
Where do HSV1 brain infections usually present?
HSV1 brain infections usually present in the inferior and medial temporal lobes
Common brain infections
-HIV/AIDS
- HIV enters CNS through incoming macrophages causing subacute inflammation
- Brain atrophy
- Memory and psychomotor speed impairment
- Depressive symptoms
- Movement disorders
HIV/AIDS associated infections (CD4 less than 200)
HIV/AIDS associated infections (CD4 less than 200)
- Toxoplasmosis
- Primary CNS lymphoma
- Cryptococcal meningitis
- JC virus (progressive multifocal encephalopathy)
- CMV encephalitis (CD4 less than 50)
HIV/AIDS associated infections (CD4 less than 200)
-Toxoplasmosis
- Reactivation from prior infection
- Parietal/frontal lobes at corticomedullary junction
- Ring enhancement
HIV/AIDS associated infections (CD4 less than 200)
-Primary CNS lymphoma
- B symptoms (fever, night sweats, weight loss)
- Large solitary lesion, diffuse ring enhancement
- Periventricular location
HIV/AIDS associated infections (CD4 less than 200)
-JC virus (progressive multifocal encephalopathy)
- Multifocal white matter lesions
- Demyelinating disease
HIV/AIDS associated infections (CD4 less than 200)
-CMV encepahlitis (CD4 less than 50)
- Ventricular enlargement
- Increased periventricular signal on T2
