RITE Images 2002 Flashcards
Demyelination – MS
Gray hue b/c of loss of myelin
Wet keratin – adamantinomatous craniopharyngioma
Subacute form of AIDS
Axial T2 weighted image showing diffuse high signal intensity throughout white matter
Aneurysm – sagittal T1 flow void
Diff dx – pituitary adenoma, meningioma, aneurysm
Radiation injury vs. recurrent brain tumor -> do FDG PET or Thallium SPECT to differentiate tumor from radiotherapy injury
**The lesion crosses ACA & MCA vascular boundaries & spares the cortex -> not a stroke!
Ragged red fibers – usually seen in mitochondrial myopathies
Kearns-Sayre myopathy
Werdnig-Hoffman – motor neuron
Duchenne’s – Dystrophin
Central core myopathy – genetic
Open ring sign w/ enhancement on GAD -> Demyelinating lesion
White matter affected
**Closed rings – GBM, lymphoma, abscess
Lesion lies in the MOTOR cortex -> frontal lobe
SDH
Spinal stenosis – narrowing of dural sac on AP & lateral contrast myelogram
Pachygyria – cortex is thick
Frontal lobe cortex is flat, white matter in that area doesn’t have the interdigitation
Occurs during 2nd trimester – neuronal migration
No middle cerebral artery
VP shunt for NPH
Optic nerve lesion extending into anterior chiasm -> temporal field defect in contralateral eye
Vasculitis – affected small & medium sized vessels “beads on a string”
Negri bodies - seen in rabies
Subpial corpora amylacea – polyglucosan bodies accumulate w/ age in astrocyte cytoplasmic processes
Chiasmal glioma
It does NOT arise from the sella
No cystic region or area of signal void to suggest craniopharyngioma
Multiple brain abscesses
Irregular Ring enhancing; mass effect
(Post-Gad images)
Not hamartomas b/c they would have a central high signal intensity on T1
Herring bodies in neurohypophyseal tissue;
- Axonal storage sites for oxytocin & vasopressin
Cyst is contiguous w/ 4th ventricle resulting from surgical excision of cerebellar astrocytoma
Hemangioblastomas – 2 of 3 which may contain cysts
GBM – post GAD, intense homogeneous, nodular, ring-like enhancement, encloses a central isointense necrotic core & delineates the gross tumor margin
Myxopapillary ependymoma
Focal conduction block of CMAP from demyelination in CIDP
Decreased amplitudes w/o axonal involvement
Intraparenchymal hematoma – high density mass w/ edema
Myokymic discharges – rhythmic & can be seen as singlets or multiplets; sometimes assoc w/ K+ channel antibodies
Metachromatic leukodystrophy (MLD) –
*white matter demyelination w/ spared U-fibers! Confluent periventricular demyelination
also can be adrenoleukodystrophy & Krabbe’s
Agenesis of corpus callosum
AD SCA Type 6 –pure cerebellar atrophy predominantly superior vermis
*NO pontine atrophy to suggest olivo-ponto-cerebellar atrophy & Machado Joseph disease;
*NO downward displacement of cerebellar tonsils & posterior fossa is not smaller than normal -> r/o ACM
*NO subarachnoid cyst b/c no cerebellar compression
A-comm artery aneurysm
Astrocytoma – infiltrating neoplasm – b/c the mass in the parasagittal parietal & occipital lobes extends into splenium of CC
*NOT PCA infarct b/c it wouldn’t cross midline
*NOT acute hematoma b/c it would be hypointense on both T1 & T2
Non-communicating/obstructive hydrocephalus
Thrombus in Vein of Galen & Straight sinus – abnormal hyperintensity on T1 & axial proton density images; hemorrhagic infarction in B thalami
B frontal contusions w/ slight orange tinge 2ndary to presence of residual hemosiderin-laden macrophages
Lacunar infarcts
Oligodendrogliomas
Reversible posterior leukoencephalopathy – found in pts w/ malignant HTN
Found in 85% of patients studied w/in 72 hrs after onset of sx
Spinal stenosis - Constricted spinal canal 2ndary to degenerative facet joint disease
*no disc herniation or synovial cyst present
Herniated disc
Myxopapillary ependymoma
AVM – need to follow up w/ cerebral angiogram
*this is a contrast enhanced CT showing a large lobulated densely enhancing structure medial to the Sylvian fissure w/ a large serpiginous structure leading from lesion posteriorly towards the vein of Galen -> need to follow up w/ angiogram
Communicating hydrocephalus
Discitis
-pt had documented E. faecalis osteomyelitis affecting L2/L3; ring enhancing
Wernicke’s encephalopathy / thiamine deficiency; mammillary bodies congested & discolored
Toxoplasmosis – ring enhancing, multiple & located in deep central grey nuclei or lobar G/W jxn.
- Iso to hypointense on T1 & hyperintense on T2 w/ mass effect & edema
- You need the question stem
Lambert eaton syndrome – incremental response cof CMAP of > 200% following exercise w/ or w/o decrement on repetitive stimulation
Creutzfeldt astrocyte – multiple small nuclei (micronuclei) & abundant eosinophilic cytoplasm
*seen in demyelinating disease
Germinoma – most common pineal region tumor
Sagittal sinus venous thrombosis – infarction w/ hemorrhage over an area of extensive cortex & in underlying white matter
*venous thrombosis assoc w/ hypercoaguable state & severe dehydration
Carbon Monoxide poisoning
Subdural hematoma
*pt presented w/ symptoms after recovery from anesthesia & is bright on T1 & T2; well known complication of spinal anesthesia & LP
Leptomeningeal melanocytes
DNET Dysembryoplastic neuroepithelial tumor
Suppurative ventriculitis – abnormal ependymal enhancement & CSF hyperdense, white matter w/ marked edema
MS
meningothelial (arachnoid) cell cluster in the fibrovascular stroma of choroid plexus
-> occasionally give rise to meningiomas (intraventricularly)
Pleomorphic xanthoastrocytoma – large cyst w/ mural nodule;
- usually found in temporal or parietal lobes
- Surrounded w/ minimal hemosiderin rim
Vein of galen aneurysm – congenital anomaly
Metastatic disease – large mass lesion filling right orbit, compressing & deforming posterior margin of globe; lateral wall of maxilla is destroyed & is assoc w/ soft tissue mass
Neurofibroma or meningioma -> surgical removal
Do not need to do CT myelogram
*intradural extramedullary
Subacute hemorrhage 2ndary to infarct (not AVM b/c it would have been bigger)
*high signal on T1
Locus ceruleus – source of NE projections
Pornecephalic cyst – lesion partially covered by arachnoid & extends from SAS to ventricular system; smooth walled & surrounded by abnormal radially oriented gyri
Hyper-dense MCA sign - Acute thrombosis of LMCA – acute MCA infarction (also look for subtle L cerebral sulcal effacement, hypodensity on L side)
Hyperdensity – due to either calcific or hemorrhagic components of acute plaque
Chronic HSV encephalitis
Encephalomalacia in both temporal lobes; can have cystic changes
Hyperintensity in temporal lobes
Neurofibrally tangle – intraneuronal intracytoplasmic inclusion composed of paired helical filaments
AD, PD, PSP, Down’s, PD complex of Guam, post-encephalitic Parkinsonism
SDH – no need for further testing à craniotomy now!
MS plaques – focal demyelination
Not epyndemoma à you’d see focal mass w/ cord enlargement
Hematoma – 2 weeks or more in age
*if you see bright on T1 & rim w/ bright on proton density weighted images (b/c of hemosiderin in macrophages surrounding hematoma)
–> methemoglobin
- *Centrotemporal spikes** -
- *Benign rolandic epilepsy of childhood;** clonic movements of face & hand that often progress to more generalized seizure
Proximal internal carotid artery has a rounded stump w/ no distal flow
-> occlusion b/c of atherosclerosis
String of beads -> Fibromuscular dysplasia (FMD)
Characteristically FMD extends from C1-2 to entrance of ICA into petrous carotid canal; 1/3 are assoc. w/ intracranial aneurysms
Common patients are young females (age 25-50).
Meningioma – intradural, extramedullary
*ependymoma, astrocytoma & hemangioblastomas – intramedullary lesions
Arachnoid cyst – (lesion @ tip of L temporal lobe) -> spares cortical ribbon & extraaxial -> r/o head trauma or HSV; the lesion looks like CSF
Dandy Walker Malformation – no vermis , 4th ventricle connects w/ cisterna magna, posterior fossa enlarged
Ependymoma – perivascular pseudorosettes
Onset latency in sensory nerve action potential; initial positivity is the AP passing beneath the active recording electrode
Jitter on single fiber EMG -> disease in neuromuscular transmission (MG) & denervating neuropathy (ALS) ;
Cervical portion of carotid -> C – petrosal segment of carotid artery -> cavernous portion
A – P-comm
B – distal ICA
D – ACA
E – A-comm
A – sylvian/lateral fissure / circular sulcus region – separates frontal & temporal lobes
B – trigone /atrium of lateral ventricle
C – genu of corpus callosum
D – frontal paranasal sinus
E – subcutaneous fat
