Neuro Flashcards
patterns of PRES
- parieto-occipital lobes
- holohemispheric at watershed zones
- superior frontal sulcus
difference between porencephaly & schizencephaly
- porencephalic cyst CSF filled lined with reactive gliosis
2. schizencephaly lined by grey matter
carbon monoxide poisoning
bilat globi pallidi necrosis
what lines virchow-robin spaces
pia
HIV encephalitis
- progressive atrophy and symmetric, periventricular or diffuse patchy/confluent white matter disease
- characteristic sparing of the subcortical-U fibers
cribriform plate is in the superior aspect of what bone?
ethmoid
which show restricted diffusion?
medulloblastoma, ATRT, ependymoma
medulloblastoma
ATRT
contents of meckels cave
CSF (90%)
fascicles CN V
trigeminal/semilunar/Gasserian ganglion
(posterolateral to cavernous sinus)
only nerve to exit dorsal brainstem
CN IV
trochlear
tram track calcification along optic nerve
optic n meningioma
recurrent laryngeal nerve sits in here bilaterally
tracheoesophageal groove
bilat vestibular schwannomas
NF2
NF2 mutation
22q12
artery of percheron infarct
central midbrain
medial thalami
NF 1 mutation
17q11.2
auto dom
100% penetrance
antibody in neuromyelitis optica
anti NMO IgG
against aquaporin 4
CN nuclei in the medulla
CN 9, 10, 11, 12
CN 7 nuclei
mid pons
normal T1 signal vertebral bodies
brighter than disc
stages of neurocysticercosis
- Vesicular (viable larva): small 10mm cysts w scolex, follows CSF, no edema
- Colloidal (dying larva): inflammation, hyperintense to CSF, enhancement, surrounding edema
- Granular nodular (healing): cyst involutes, wall thickens, edema ↓
- Nodular calcified (healed): no edema, MR black dots
cause of neurocysticercosis
taenia solium
findings of NFI
‘substance’
- waxing/waning WM lesions (UBO, FASI)
- optic n glioma
- optic pathway glioma
- brain gliomas (brainstem, cerebral, basal ganglia)
- [plexiform] neurofibroma
- vascular dysplasia
- cafe au lait spots
- dysplastic skeletal lesions
findings of NFII
‘layers’
- multiple CN schwannomas
- meningiomas
- spinal tumors/ependymomas
MISME - multiple inherited schwannomas meningiomas and ependymomas
clinical criteria of NFI
2+ of:
≥ 6 café au lait spots ≥ 15 mm adults or 5 mm children
≥ 2 neurofibromas or 1 plexiform neurofibroma
Axillary/inguinal freckling
Visual pathway glioma
≥ 2 iris hamartomas (“Lisch nodules”)
Distinctive bony lesion (sphenoid wing dysplasia, thinning of long bone ± pseudoarthrosis)
1st-degree relative with NF1
% inverted sinonasal papilloma convert to/coexist w/ SCCa
10%
gene affected in NFIII (schwannomatosis)
SMARCB1
length of MS spinal lesions
usually <2 vert bodies
length of transverse myelitis lesions
usually >2 vert bodies
most common intramedullary neoplasm in adults
ependymoma
second most common intramedullary neoplasm in adults
astrocytoma
most common intramedullary spinal neoplasm in kids
astrocytoma
length of NMO lesions
usually >3 vert bodies
criteria for NMO (Devic)
2/3 of:
- Contiguous cord lesion 3 or more segments in length
- initial brain MR nondiagnostic for MS
- NMO-IgG seropositivity
cannot distinguish NMO from this if optic neuritis and myelitis on 1st scan:
ADEM - acute disseminated encephalomyelitis
mutation in CADASIL
NOTCH3 - chromosome 19
stroke in middle aged, healthy adults
think CADASIL
classic triad susac syndrome
Encephalopathy
Branch retinal artery occlusions
Hearing loss
most common meningitis bugs
- strep pneumo
- n meningitidis
- haemophilus influenzae
most common CNS fungal infection
cryptococcosis
most common CNS infection worldwide
cysticercosis
most common tumor in chronic temporal lobe epilepsy
ganglioglioma
association with dysplastic cerebellar gangliocytoma (lhermitte-duclos disease)
cowden syndrome
10q23
1 CNS neoplasm in tuberous sclerosis
subependymal giant cell astrocytoma
most common tumor in cauda equina region
myxopapillary ependymoma
glomus tympanicum paraganglioma vs glomus jugulare –> floor in tact vs destroyed
in tact = tympanicum; destroyed = jugulare
only CN withIN the cavernous sinus
CN6 abducens
‘cold’ spondylodiscitis causes
Tb
Brucella
rhomboencephalitis involves what
hindbrain = cerebellum and brainstem
bacteria in lemierre’s
Fusobacterium necrophorum
gradenigo syndrome triad & cause
- otitis media
- periorbital pain (CN V)
- abducens palsy (CN VI)
cause: petrous apicitis
association of T2 FLAIR mismatch
highly specific for IDH-mutated 1p/19q non-codeleted astrocytoma
(vs other lower grade gliomas, oligodendroglioma)
most common met to parasellar region
breast ca
syndrome caused by compression of tectal plate
parinaud syndrome
- upward gaze paralysis
- pupillary light dissociation
- nystagmus
central Ca2+ pineal gland
exploded Ca2+ pineal gland
- germinoma
- pineoblastoma
1 extraaxial hematoma
traumatic SAH
2 extraaxial hematoma
acute subdural
terson syndrome
intraocular hemorrhage with SAH
recurrent artery of Heubner supplies…
- head and anteromedial caudate nucleus
- anterior limb internal capsule
medial lenticulostriate arise from?
lateral?
A1
MCA
calcifications of pineoblastoma and germinoma
blastoma blasts apart the Ca2+
germinoma enGulfs the Ca2+
causes of convexal SAH (#10)
- dural sinus and cortical vein thrombosis
- arteriovenous malformations
- dural arteriovenous fistulas
- arterial dissection/stenosis/occlusion
- mycotic aneurysm
- vasculitides
- amyloid angiopathy
- coagulopathies
- RCVS
- posterior reversible encephalopathy syndrome
inheritance of sturge weber
sporadic
path of CN 6 (abducens)
- front of pons (medial to 5)
- up durrelos canal (clivus)
- through cavernous sinus
- up through superior orbital fissure
- orbit
- lateral rectus
brain tumor classically Ca2+
oligodendroglioma
cerebrovascular malformations w/ arteriovenous shunt
- AVM
- dural AV fistula
- vein of galen malformation
wyburn mason syndrome
AVMs of retina and brain
optic canal contents
optic nerve CNII
ophthalmic artery
superior orbital fissure contents
CN III CN IV CN V1 CN VI sup'r and inf'r ophthalmic veins
longest cranial nerve
CN IV - trochlear
posterior decussation
Marchiafava-Bignami disease
rare, alcoholics
osmotic demyelination & necrosis of corpus callosum central fibers (sandwich sign on sagittal)
FLAIR hyperintense, nonenhancing T1 hypointense
Dandy Walker malformation
- large posterior fossa
- cyst extending posteriorly from 4th ventricle
- vermian agenesis/hypoplasia
- torcular-lambdoid inversion
Ramsay Hunt syndrome
shingles/herpes zoster of facial n
- VZV reactivation in geniculate ganglion
- triad: ear pain, facial paralysis, painful vesicular eruption involving EAC, pinna, tongue or hard palate
oxyhemoglobin: time, RBC, T1 and T2 signal
hyperacute (<1 day)
RBC intact
T1 iso
T2 bright
deoxyhemoglobin: time, RBC, T1 and T2 signal
acute (1-3 days)
RBC intact
T1 iso
T2 dark
methemoglobin (intracellular): time, RBC, T1 and T2 signal
early subacute (3-7 days)
RBC intact
T1 bright
T2 dark
methemoglobin (extracellular): time, RBC, T1 and T2 signal
late subacute (7 to 14-28 days)
RBC lysed
T1 bright
T2 bright
hemosiderin: time, RBC, T1 and T2 signal
chronic (>14-28 days)
RBC lysed
T1 dark
T2 dark
ecchordosis physaliphora
ectopic notochord remnant
anywhere from dorsum sella to sacrum
Aunt Minnie: clival defect/cystic lesion with sclerotic margins
Tornwaldt cyst
- benign midline nasopharynx mucosal cyst
- high T2 signal
- notochordal remnant
Wallenberg/lateral medullary syndrome
occlusion of intracranial VA and/or PICA -> infarct of lateral medulla
- dysphagia (nucleus ambiguus), dysarthria, dysphonia
- ipsilat loss of pain in face
- contralat loss of pain & temp in body
+/- ataxia
embryonic carotid-basilar anastomoses
- persistent trigeminal artery (btwn cavernous ICA and basilar artery; Neptune’s trident)
- persistent hypoglossal artery (btwn prox cervical ICA at ~C1-2 level and BA; courses along CN XII through hypoglossal canal)
- persistent otic artery (rare)
- proatlantal/intersegmental artery (rare)
persistent stapedial artery - embryology, course
- stapedial a transiently present in N fetal devel, connecting branches of future ECA to ICA
- arises from C2/petrous ICA
- pass thru stapes footplate, doubles size of anterior/tympanic seg of facial n
- intracranially becomes middle meningeal artery
- assoc w aberrant ICA
persistent stapedial artery - CT findings
- absence of foramen spinosum
- enlarged tympanic seg of facial n (contains soft tissue)
aberrant ICA - course, clinical
- laterally displaced ICA
- enters posterior middle ear cavity from below and hugs cochlear promontory as it crosses middle ear cavity
- then resumes N expected course as it joins post-lat margin of horizontal petrous ICA
- pulsatile tinnitus, vascular retrotympanic mass in anteroinferior mesotympanum
- mimics glomus tympanicum
- assoc w persistent stapedial a
aberrant ICA - imaging CT & angio
CT:
- tubular lesion crossing middle ear cavity from posterior to anterior
- soft tissue density lying on cochlear promontory
Angio:
- angulation resembling a 7, change in contour and caliber (pinched appearance)
CADASIL - imaging
- symmetric high T2 subcortical WM
- anterior temporal lobes + external capsules
+ lacunar infarcts
CADASIL - clinical
recurrent stroke/TIA + migraine -> premature dementia
young adult
reversible cerebral vasoconstriction syndrome
multifocal segmental arterial constrictions
- multiple vascular territories
- beaded appearance
high res wall imaging: +/- thickened wall, reduced lumen; no/minimal enhancement
convexal SAH, strokes
moyamoya - imaging
progressive stenosis of distal (supraclinoid) ICA and proximal CoW, eventual occlusion
anterior > posterior circulation
enlarged/innumerable basal perforating arteries, lenticulostriate collaterals
puff of smoke
children stroke, adults bleed
ivy sign in moyamoya
tubular branching FLAIR hyperintensities within sulci
represent cortical arterial branches that appear FLAIR hyperintense d/t slow collateral flow
+ vivid contrast enhancement
age of esthesioneuroblastoma (olfactory neuroblastoma)
> 50
most common benign orbit lesion adult
hemangioma
most common suture to close prematurely
sagittal
Prussak space boundaries
lateral: pars flaccida & scutum
superior: lateral malleal ligament
medial: neck of malleus
(subcomponent of the lateral epitympanic space)
nuc med imaging for esthesioneuroblastoma
- neuroendocrine tumor –> somatostatin receptor
- octreotide
- MIBG
- DOTATATE
Spetzler Martin scale for AVMs
predicts surgical morbidity/mortality
ranges from 1-5 pts:
- size: <3cm (1), 3-6cm (2), >6cm (3)
- location: noneloquent (0), eloquent area of brain (1)
- venous drainage: superficial (0), deep (1)
triangle of Guillain & Mollaret
dentatorubro-olivary pathway:
- contralateral dentate nucleus (lateral cerebellar nuclei)
- red nucleus (tegmentum of midbrain)
- inferior olivary nucleus (medulla)
damaged in hypertrophic olivary degeneration
hypertrophic olivary degeneration
hypertrophied & T2 hyperintense inferior olivary nucleus with a causative lesion in the brainstem:
- infarct, hemorrhage, demyelination, surgery
damage to triangle of Guillain & Mollaret
dysembyroplastic neuroepithelial tumor
“bubbly” lesion without mass effect
cortically based
wedge shaped
multilobulated
young pt with longstanding hx of seizures
mesial temporal sclerosis imaging findings
reduced hippocampal volume
increased T2 signal (gliosis, scar)
loss of normal interdigitations
late:
atrophy of ipsilateral fornix & mammillary body
Wernicke’s encephalopathy: affected areas
mammillary bodies
dorsomedial thalami
periaqueductal grey matter
tectal plate
nonketotic hyperglycemia with hemichorea-hemiballismus: imaging appearance
hyperdense (CT) and T1 hyperintense basal ganglia (esp putamen) contralateral to side of movement disorder
normal signal on T2 & DWI
spinal AVM/AVF classification
type 1: dural AVF (single coiled vessel, MC: 85%)
type 2: intramedullary nidus from ant or post spinal a (+/- aneurysm, SAH; assoc w HHT, KTS)
type 3: juvenile (very rare, complex, bad prog)
type 4: intradural perimedullary (near conus, subtypes: single vs multiple arterial supply)
pterygopalatine fossa: 6 openings
- inferior orbital fissure (anterosup/“roof”) → orbit
- sphenopalatine foramen (medial) → nasopharynx via superior meatus (*origin of JNA)
- pterygomaxillary fissure (lateral) → masticator space
- foramen rotundum (posterosup) → middle cranial fossa
- vidian canal (posteroinf) → directly below f. rotundum
- greater & lesser palatine foramina(inferior/“floor”) → oral cavity
syndrome associated with multiple DVAs
blue rubber bleb nevus syndrome
genes associated with cavernomas
CCM1 (KRIT1)
CCM2 (OSM)
CCM3 (PDCD10)
most common cerebral vascular malformations
- DVA
- capillary telangiectasia
- cavernoma
Sturge Weber dominant findings
- unilateral port wine stain (nevus flammeus), usually V1 trigeminal n
- ipsilateral cerebral atrophy with cortical/subcortical tram-track calc’n (d/t vascular steal phenomenon)
- choroidal angiomas (choroidal enhancement of globe)
- leptomeningeal angiomatosis (diffuse leptomeningeal enhancement ipsilateral to facial port wine stain)
(seizures, hemiparesis)
2 branches of C2 (ICA)
- vidian artery
- caroticotympanic artery
(can get persistent stapedial artery from here)
C3 (ICA) covered by what?
- trigeminal ganglion
- no branches
C4 (ICA) 2 important branches
- meningohypophyseal trunk (supply pituitary, tentorium, clival dura)
- inferolateral trunk (supply cranial nerves and CS dura)
C6 (ICA) 2 important branches
- ophthalmic artery
2. superior hypophyseal (supply anterior pit lobe, infundibular stalk, optic chiasm)
C7 (ICA) 2 important branches
- posterior communicating artery
2. anterior choroidal artery
distal ICA passed between which two cranial nerves?
optic & oculomotor
absent foramen spinosum and enlarged anterior facial nerve segment = ?
persistent stapedial artery
intracranial becomes middle meningeal artery
most common circle of willis variant
hypoplastic or absent posterior communicating
association with agenesis of corpus callosum (#6)
- gray matter heterotopia
- Chiari II malformation
- lissencephaly
- Dandy-Walker
- cytomegalovirus infection
- fetal alcohol syndrome
associations with schizencephaly
- septo-optic dysplasia
- corpus callosum anomalies
- grey matter heterotopia
- absent septum pellicidum
(grey matter lined cleft extending from ependyma to pita mater)
facial nerve segments
“I Love Going To Makeover Parties”
Intracranial/cisternal (medial to vestibulocochlear n)
Meatal/canalicular (anterosuperior IAC)
Labyrinthine (exits IAC anteriorly thru fallopian canal, reaches genu anteriorly)
Geniculate (gives off greater petrosal n)
Tympanic (geniculate ganglion to pyramidal eminence)
Mastoid (pyramidal eminence inferiorly to stylomastoid foramen, gives chorda tympani)
Parotid/Extracranial (stylomastoid foramen to division into major branches)
facial nerve terminal motor branches
“Tall Zulus Bear Many Children”
“To Zanzibar By Motor Car”
Temporal Zygomatic Buccal Mandibular Cervical
VHL findings
- multiple hemangioblastomas
- ocular angiomas
- pancreatic and renal cysts
- renal cell carcinoma
- pheochromocytoma
- cystadenomas
- islet cell tumors
- endolymphatic sac tumors
VHL tumor suppressor gene (auto dom’t)
dorello canal
bony canal
transmits CN VI/abducens nerve
from prepontine cistern to cavernous sinus
superior orbital fissure contains which nerves?
CN III, IV, V1 ophthalmic, VI
“Lazy French Tarts Sit Nakedly In Anticipation” (sup to inf)
L: lacrimal n (branch CN V1) F: frontal n (branch CN V1) T: trochlear n (CN IV) S: superior division of the oculomotor n (CN III) N: nasociliary n (branch of CN V1) I: inf division of oculomotor n (CN III) A: abducens n (CN VI)
foramen rotundum contains…
CN V2 maxillary
foramen ovale contains…
CN V3 mandibular
accessory meningeal artery
foramen spinosum contains…
middle meningeal artery & vein
meningeal br of V3
inferior orbital fissure contains…
“Inferior Orbit Gets Infra-Orbital Nerves and VeinZ”
IO: inferior ophthalmic vein (tributary to both pterygoid venous plexus & cavernous sinus)
G: ganglionic branches from pterygopalatine ganglion to maxillary div. of trigeminal n.
ION: infraorbital nerve (branch CN V2)
A: infraorbital artery (branch maxillary artery)
V: infraorbital vein
Z: zygomatic nerve (branch CN V2)
pars nervosa contains…
CN 9 + its tympanic branch Jacobsen’s nerve
inferior petrosal sinus
(anteromedial to pars vascularis)
pars vascularis contains…
CN 10 + its auricular branch Arnold’s nerve
CN 11
jugular bulb
posterior meningeal br of ascending pharyngeal art
(posterolateral to pars nervosa)
what branches of the trigeminal nerve are in which foramen?
Standing Room Only
S: Superior orbital fissure - V1 ophthalmic
R: foramen Rotundum - V2 maxillary
O: foramen Ovale - V3 mandibular
mesial temporal sclerosis: hippocampus findings
volume, signal, morphology
- reduced volume/atrophy
- increased T2 signal
- abN morphology: loss of internal architecture (interdigitations of hippocampus)
cerebral peduncles
1 pair (vs 3 pairs of cerebellar peduncles)
- anterior part of midbrain that connects remainder of brainstem to thalami
- separated by interpeduncular cistern
- contain large white matter tracts that run to and from the cerebrum
cerebellar peduncles
3 pairs (vs 1 pair of cerebral peduncles)
- superior cerebellar peduncles (brachium conjunctivum): cerebellum to midbrain
- middle cerebellar peduncles (brachium pontis): cerebellum to pons
- inferior cerebellar peduncles: cerebellum to medulla
blood supply to superior cerebellar peduncle
superior cerebellar artery (SCA)
blood supply to middle cerebellar peduncle
anterior inferior cerebellar artery (AICA)
superior cerebellar artery (SCA)
blood supply to inferior cerebellar peduncle
posterior inferior cerebellar artery
what is an infundibulum (artery)
- conical outpouching from an artery with a broad base narrowing to an apex
- must be a vessel that originates from apex (may not be visible on imaging)
- commonly at origin of PCOM from supraclinoid ICA
- no risk for rupture/SAH (vs aneurysm)
ICA segments (Bouthillier)
C1: cervical C2: petrous (horizontal) C3: lacerum C4: cavernous C5: clinoid C6: ophthalmic (supraclinoid) C7: communicating (terminal)
branches of petrous (horizontal) segment of ICA
- caroticotympanic artery
- Vidian artery
branches of lacerum segment of ICA
none
branches of cavernous segment of ICA
- meningohypophyseal trunk
- inferolateral trunk
- capsular arteries (of McConnell) (variable)
branches of clinoid segment of ICA
none
branches of ophthalmic (supraclinoid) segment of ICA
- ophthalmic artery
- superior hypophyseal artery
branches of communicating segment of ICA
- posterior communicating artery
- anterior choroidal artery
- anterior cerebral artery
- middle cerebral artery
idiopathic intracranial hypertension - findings
optic nerves: prominent SAS around CNII, vertical tortuosity/kinking, papilledema
enlarged arachnoid outpouchings: empty sella turcica, enlarged Meckel cave, prominent arachnoid granulations within temporal bone, sphenoid wing
bilateral venous sinus stenosis: junction of transverse & jugular sinuses (most important finding)
uncommon: slit-like ventricles, acquired tonsillar ectopia
Tolosa Hunt
granulomatous inflammatory condition involving cavernous sinus and orbital apex
- clinical dx of exclusion: painful ophthalmoplegia 2/2 to surrounding cavernous sinus inflammation
CT: asymmetrical enlargement +/- enhancement
MRI: T1 iso-hyper, T2 hyper, enhancement
facial nerve - typical enhancing vs nonenhancing segments
Mild enhancement of geniculate ganglion, and proximal tympanic segments
Bad enhancement: “proximal to genu, distal to SMF”
- cisternal, meatal & labyrinthine segments: surrounded by CSF, should NOT enhance
- extracranial segment: should NOT enhance
3 important intratemporal branches of facial nerve, top to bottom (Osborn)
greater superficial petrosal nerve
- parasymp fibers supplying lacrimal gland
stapedius nerve
- innervate stapedius muscle
chorda tympani
- taste from anterior 2/3 of tongue
internuclear ophthalmoplegia
disorder of conjugate gaze (ability of eyes to move in same direction at same time):
- impaired adduction in ipsilateral eye
- dissociated horizontal nystagmus of contralateral abducting eye
- d/t lesion in medial longitudinal fasciculus (MLF) ipsilateral to eye unable to adduct
- e.g. MS, NMO, infarct
CN III palsy: pupil-involving vs. pupil-sparing
pupil-involving (enlarged unreactive pupil):
- compression of CN III, because parasympathetic pupillary fibers are located peripherally in the nerve which are more likely affected by external compression
- causes: PCoA & SCA aneurysms, uncal herniation
pupil-sparing:
- cause: ischemia (microvascular infarction of the core of the nerve with relative sparing of its peripheral fibers)
ulegyria
shrunken cortex with flattened, mushroom-shaped gyri, d/t global hypoxic ischemic injury in term infants
centers on deepest portion of gyri, usually in parasagittal region/parietooccipital area
- it is here that perfusion is most tenuous and, therefore, most susceptible to ischemic damage
gelastic seizures
gelastic = laughing spells
think hypothalamic hamartoma
benign non-neoplastic heterotopias, arising from tuber cinereum
neuronal migrational disorders
cortical heterotopia
polymicrogyria/pachygyria
schizencephaly
lissencephaly
aditus ad antrum
(aka otomastoid foramen or entrance or aperture to mastoid antrum; Latin: “entrance to the cave”)
def’n: the short passageway coneccting epitympanum to mastoid antrum (the large central mastoid air cell posterior to middle ear up to 1 cm)
Koerner septum
- thin bridge of bone dividing petrous & squamous portion of mastoid air cells at level of mastoid antrum
- serves as barrier to extension of infection from lateral to medial mastoid air cells
- commonly eroded by middle ear cholesteatomas
- important surgical landmark within mastoid air cells
pyramidal eminence (or process)
- small hollow anterior osseous protrusion from posterior wall of mesotympanum of petrous temporal bone
- separates sinus tympani medially from facial recess laterally
- stapedius muscle arises from the hollow of the pyramidal process, passes anterior out of apex of pyramidal eminence to attach to posterior aspect of neck of stapes
cochlear promontory
bone that overlies basal turn of cochlea protruding into middle ear cavity
- glomus tympanicum paragangliomas typically arise in the region of the cochlear promonotory
tensor tympani muscle
connects to malleus bone, pull down handle medially which tenses tympanic membrane, reducing amplitude of oscillations
supplied by nerve to medial pterygoid (branch of CNV3/mandibular n)
arises from cartilaginous part of Eustachian tube, greater wing sphenoid, petrous temporal bone;
passes into protympanum of tympanic cavity,
reflects at cochleariform process, inserts into upper end of handle of malleus
muscles of the temporal bone
tensor tympani muscle: stabilizes malleus
stapedius muscle: stabilizes stapes
both function to dampen sound, prevents damage to inner ear from loud sounds
stapedius muscle
smallest skeletal muscle in human body
stabilizes stapes (smallest bone in body)
stapedius muscle belly located in pyramidal eminence
stapedius tendon attaches to head of stapes
innervated by CNVII
ossicles of middle ear
malleus (anterior): umbo + manubrium + head
incus (posterior): short process, body, long process, lenticular process
stapes (medial): head, crura, footplate
branches of external carotid artery
"Some Ancient Lovers Find Old Positions More Stimulating" "Some Angry Lady Figured Out PMS" arising from the carotid triangle: - superior thyroid artery - ascending pharyngeal artery - lingual artery - facial artery - occipital artery - posterior auricular artery
terminal branches:
- (internal) maxillary artery
- superficial temporal artery
sinus tympani
clinical blind spot during standard mastoid approach to T-bone, where cholesteatomas may hide
medial wall contains: lateral SCC, tympanic segment of facial n, and oval & round windows
Prussak space
lateral epitympanic recess
classic location for acquired (pars flaccida) cholesteatoma
5 bony parts of temporal bone
- squamous: lat wall of middle cranial fossa
- mastoid
- styloid
- tympanic: U-shaped bone, forms most of bony external ear
- petrous: contains middle & inner ear, IAC, petrous apex
- 2 important structures anteriorly: tegmen tympani (roof of tympanic cavity) & arcuate eminence (over SCC; surgical landmark along middle cranial fossa floor)
round window
- 1 of 2 openings in middle ear
- basal turn of cochlea ends at round window
- communication btwn mesotympanum of middle & inner ear
- vibrates with opposite phase to vibrations from inner ear, producing movement of perilymph in cochlea
- absence or rigidity assoc w hearing loss
oval window
kidney-shaped aperture in medial wall of mesotympanum of middle ear
communication w vestibule of inner ear
footplate of stapes is attached to its rim by annular ligament
best visualized in coronal plane
epi/meso/hypotympanum
- mesotympanum (directly medial to tympanic membrane): btwn axial plane from tip of scutum to tympanic segment of facial n & axial plane from tympanic annulus to base of cochlear promontory
- epitympanum (attic): above axial plane from tip of scutum to tympanic segment of facial n
- hypotympanum: below axial plane from tympanic annulus to base of cochlear promontory
basal lamella (of the middle turbinate)
osseous lamella that separates anterior from posterior ethmoid sinuses
singular canal (aka foramen singulare, singular foramen)
thin channel within petrous temporal bone that carries singular nerve from IAC
- normal structure that may be mistaken for a temporal bone fracture
- surgical landmark during retrosigmoid approach to IAC, in which posterior wall is removed up to point of singular canal but no further to avoid fenestration of labyrinth
inner ear structures
bony labyrinth/otic capsule (BL) + membranous labyrinth (ML):
- BL & ML are separated by perilymph (Na+), which does not communicate w endolymph (K+) contained in membranous labyrinth
- cochlea (BL) housing cochlear duct (ML) for hearing
- vestibule (BL) housing utricle & saccule (ML) for static balance
- semicircular canals (BL) housing semicircular ducts (ML) for kinetic balance
Keros classification
classifies depth of recess above cribriform plate, i.e. depth of olfactory fossa
Keros I: ≤ 3 mm
Keros II: 4-7 mm
Keros III: >7 mm
Haller cell
cell in medial antrum, under orbital floor
next to infundibulum
may obstruct sinus drainage
Agger Nasi cell
most anterior ethmoid air cell
fovea ethmoidalis
lateral roof of ethmoid sinus
extension of orbital plate of frontal bone
most common complication of functional endoscopic sinus surgery (FESS)
CSF leak
the deeper the cribriform plate with respect to fovea ethmoidalis (higher Keros), the greater chance of CSF leak
neck lymph node size criteria
long axis on axial plane 1A (submental): 0.8cm (midline) retropharyngeal: 0.8cm 1B: 1.5cm 2A (jugulodigastric/node of Ranvier): 1.5cm all others: 1cm
Onodi air cell
- sphenoethmoidal air cell above & lateral to sphenoid sinus
- coronal: locate air cell above sphenoid sinus and identify its continuity with a posterior ethmoid air cell
- places optic nerve at risk for intraoperative injury during posterior ethmoidectomy
maxillary antrum drainage
via ostiomeatal unit into MIDDLE MEATUS
(drains via maxillary ostium into infundibulum, then through hiatus semilunaris into MIDDLE MEATUS)
(best plane: coronal)
frontal sinus drainage
via ostiomeatal unit into MIDDLE MEATUS
(more variable than other paranasal sinuses;
frontal infundibulum -> frontal recess -> 2 main variations:
- drainage into ethmoidal infundibulum, through hiatus semilunaris into middle meatus
- drainage directly into middle meatus)
(best plane: coronal & sagittal)
anterior ethmoid sinus drainage
via ostiomeatal unit into MIDDLE MEATUS
(drain to hiatus semilunaris and middle meatus via ethmoid bulla, which forms parts of ostiomeatal complex)
(best plane: coronal & sagittal)
posterior ethmoid sinus drainage
via sphenoethmoidal recess into superior meatus
best plane: sagittal
sphenoid sinus drainage
via sphenoethmoidal recess into roof of nasal cavity
best plane: axial
Weber syndrome
midbrain stroke syndrome (PCA) involving cerebral peduncle & ipsilat fascicles of oculomotor n
- ipsilat CN III palsy (diplopia, ptosis, afferent pupillary defect)
- contralat hemiplegia/paresis (corticospinal/corticobulbar tracts)
- contralat parkinsonian rigidity (if substantia nigra involved)
nerves involved in taste
facial n: anterior 2/3 of tongue (via chorda tympani & greater superficial petrosal nerve
glossopharyngeal n: posterior 1/3 of tongue
vagus n: epiglottis region
hypoglossal nerve innervates what
all intrinsic and extrinsic muscles of tongue except palatoglossus muscle (vagus n)
only CN with purely motor function
through what structure are cochlear implants inserted?
round window
what is the soft tissue component of the vestibular aqueduct?
endolymphatic sac
what is the density in the centre of the cochlea?
modiolus
what does the singular canal transmit?
singular nerve
- branch of inferior vestibular nerve
- carries afferent information from posterior semicircular canal
trilateral retinoblastoma
pineoblastoma + bilateral retinoblastoma
Foix-Alajouanine syndrome
spinal dural AV fistula + progressive myelopathy
- initially: spastic paraplegia, then flaccidity, loss of sphincter control & ascending sensory level
- thought to be d/t venous hypertension
cavernous sinus drainage
- inferiorly through foramen ovale to pterygoid venous plexus
- posteriorly clival venous plexus, superior & inferior petrosal sinus
most common tumour associated with temporal lobe epilepsy
ganglioglioma
features ganglioglioma
50% calcify
cyst w/ enhancing nodule
can be solid
DNET (dysembryoplastic neuroepithelial tumor)
- bubbly
- no enhancement
- swollen gyrus
pleomorphic xanthroastrocytoma
- cortical/subcortical
- solid/cystic
- +/- enhancing cyst
- peritumoral edema
- +/- enhancing meningeal C+ adjacent
bug to cause necrotizing otitis externa
pseudomonas aeurginosa
etiology of and most common place of origin for plunging ranula
- Mucous retention cyst from obstructed sublingual gland/minor salivary gland
- sublingual space
epidermoid cyst
CSF-Iike extra-axial non-enhancing mass that is bright
on DWl
arachnoid cyst
Non-enhancing unilocular extra-axial lesion
that follows CSF on all imaging modalities, including
DWl
epidermoid vs arachnoid cyst
both C- CSF-like but
- epidermoid bright on DWI
risk factors nasopharyngeal carcinoma vs squamous cell carcinoma
- nasopharyngeal = southern china, EBV virus
2. SCC = tobacco, EtOH, HPV 16
staging nasopharyngeal carcinoma
Tx: primary not assessed
T0: no evidence of primary but EBV+ cervical node involvement
T1: NO parapharyngeal extension (NP +/- oropharynx, nasal cavity)
T2: WITH parapharyngeal extension
T3: involve bone
T4: extension: intracranial, CN, orbit, masticator space, hypopharynx
staging HPV (-) oropharynx (p16 negative)
Tx: cannot be assessed
Tis: carcinoma in situ
T1: max diameter <2 cm
T2: 2-4 cm
T3: >4 cm or to lingual surface of epiglottis
T4a (moderately advanced): involves larynx, extrinsic tongue, medial pterygoid, hard palate, mandible
T4b (very advanced): involves lateral pterygoid, pterygoid plate, lateral nasopharynx, skull base, encases carotid art
staging HPV (+) oropharynx (p16 positive)
T0: not seen
T1: max diameter <2 cm
T2: 2-4 cm
T3: >4 cm or to lingual surface of epiglottis
T4: involves larynx, extrinsic tongue, medial pterygoid, hard palate, mandible or more
paraganglioma - most common arterial supply
ascending pharyngeal artery
how far down do these go:
- retropharyngeal space
- danger space
- avg T3 (C7-T6)
- diaphragm
imaging down to carina/T6 at least if ?mediastinitis
location of mucocele
F>E>M>S
frontal > ethmoid > maxillary > sphenoid
location of conus medullaris
depends on growth of vertebral bodies
term: L2-3
3 months post-natal: L1-2
abnormal if below inferior endplate of L2
Brown Séquard Syndrome
decreased pain and temperature in one leg
motor weakness on the other side
spinal cord herniation vs dorsal arachnoid cyst on CT myelogram
spinal cord herniation - no contrast separating it from ventral dura
dorsal arachnoid cyst - thin rim of contrast should be seen anterior to the cord
types of diastematomyelia
type I: 2 distinct dural sacs (bony/cartilage spur, symptomatic)
type II: 1 dural sac (fibrous spur, asymptomatic)
most common malignancy of thyroglossal duct cyst
papillary thyroid carcinoma
CT myelogram difference arachnoid cyst & neurenteric cyst
- arachnoid POSTERIOR (dorsal)
2. neurenteric cyst ANTERIOR (ventral)
wide-neck cerebral aneurysm - definition
dome to neck ratio >2:1
absolute cut off: >4mm neck diameter
pituitary stalk interruption syndrome: triad
ectopic posterior pituitary gland
thinned or absent pituitary stalk
absent or hypoplastic anterior pituitary gland
Modic I-III changes
Type I: T1 low, T2 high, T1C+
Type 2: T1 high, T2 iso to high
Type 3: T1 low, T2 low
perivascular anatomic route for nasopharyngeal carcinoma to access intracranial structures
foremen lacerum
cartilaginous floor of anterior horizontal petrous ICA
perineural route of spread from masseter space to access intracranial structures occurs along…
CNV3 - mandibular
through foramen ovale into Meckels cave and beyond
what is the connection between buccinator and superior pharyngeal constrictor muscles and its significance?
pterygomandibular raphe
- fibrous band extending from hamulus of medial pterygoid plate above to posterior mandibular mylohyoid line below
- lies beneath mucosa of retromolar trigone
- perifascial route of spread for retromolar trigone SCCa
what structure separates the lower oral cavity into the submandibular and sublingual spaces?
mylohyoid muscle (except along free posterior margin)
what is the retromolar trigone?
small, triangular-shaped region of mucosa behind 3rd/last molar on mandibular ramus
- anatomical crossroads of oral cavity, oropharynx, soft palate, buccal space, floor of mouth, masticator space, and parapharyngeal space
parotid primary drainage site for what?
scalp
external auditory canal
deep facial structures
most common parotid tumor
benign mixed tumor
aka pleomorphic adenoma
Earliest signal change sequences for:
- CJD
- HSV
- autoimmune encephalitis
- hypoxic ischemic injury
- hyper acute infarct
- SAH
CJD: DWI HSV: DWI Autoimmune encephalitis: FLAIR HIE: DWI & spec (lactate, glutamine-glutamine) Infarct: DWI SAH: FLAIR
Most common source deep neck infection
Most common deep neck infection
Tonsilitis
Peritonsillar abscess
Most common facial bone fracture adult and peds
Most common orbit fracture
Adult/peds = nasal bone
Peds mandible > orbital adult
Most common orbit = inferior orbit wall
cranial nerve V3 (mandibular) is sensory/motor to:
Sensory: - mandible (except angle) - preauricular - meninges - mouth (taste via chorda tympani CN VII) Motor: - masticator muscles - tensor veli palatini - mylohyoid - anterior belly digastric
how to confirm PML (progressive multifocal leukencephalopathy)
confirm JC virus antibody in CSF using PCR
Toxo vs CNS Lymphoma on nuc med & MRS
Toxo:
no uptake on SPECT or PET
lipid and lactate peaks
decreased CBV
Lymphoma: uptake on SPECT or PET decreased NAA choline peak \+/- lipid and lactate peak usually increased CBV
carbon monoxide poisoning vs methanol poisoning
CO: CT hypo/T2 bright globes pallidus (CO causes globus warming)
Methanol: T2 bright putaminal (May hemorrhage, CT hyper)
T1 bright basal ganglia
Copper and manganese deposition
- nonspecific
- related to liver disease
- TPN, Wilson’s, nonketotic hyperglycemia
What sequence is most sensitive for juxtacortical and periventricular plaques in MS?
Infratentorial?
Juxtacortical - FLAIR
infratentorial - T2
MR spec in MS
Reduced NAA peaks in the plaques
First bone eroded by pars flaccida cholesteatoma
Incus (adjacent to prussaks space)
Retinoblastoma
Bilateral
Trilateral
Quadrilateral
Bilateral 30% of the time
Trilateral = eyes plus pineal
Quadrilateral = eyes, pineal, suprasellar
features parathyroid adenoma on 4D ct scan
- NECT - hypoattenuating relative to thyroid
- C+ art - can hyperenhance
- C+ delayed washout
- C+ delayed washout
% cavernomas with associated DVA
30%
white matter tracts found in agenesis of corpus callosum
bundles of probst
delayed radiation myelopathy
6-24 months post radiation
foix alajouanine syndrome
venous congestive myelopathy due to a spinal arteriovenous malformation, presenting as subacute progressive neurological deterioration. Initially, patients have a spastic paraplegia which progresses to flaccidity, loss of sphincter control, and ascending sensory level.
