NEURO 3 Flashcards
Order of myelination
- inferior to superior
- posterior to anterior
- central to peripheral
- sensory then motor
last structures to myelinate
subcortical white matter (occipital at 12 months, frontal at 18 months)
structures that are myelinated at birth
- posterior limb of internal capsule
- brainstem
order of sinus formation
maxillary –> ethmoid –> sphenoid –> Frontal
what structures are in the superior orbital fissure
CN 3, CN4 ,CN V1, CN6
what structures are in the inferior orbital fissure
V2
Segments of the ICA
C1: cervical
C2: petrous:
C3: Lacerum
C4: cavernous
C5: clinoid - aneurysm can compress CN2
C6: Supraclinoid (Ophthalmic) - common site for aneurysm; originats at dural ring
C7: communicating/terminal - aneurysm can compress CN3
What structure can get compressed with a subfalcine herniation
The cingulate gyrus is herniated under the falx, and if progression occurs, other areas of the frontal lobe are involved
Complications
hydrocephalus due to obstruction of the foramen of Monro
anterior cerebral artery (ACA) territory infarct due to compression of ACA branches, specifically the pericallosal artery
focal necrosis of the cingulate gyrus due to direct compression against the falx cerebri
ACA infarction occurs as the cingulate sulcus extends under the falx dragging the ipsilateral anterior cerebral artery with it. If this becomes compressed against the falx, distal anterior cerebral artery infarction can occur, the most common clinical manifestation being contralateral leg weakness.
In subfalcine herniation, the degree of midline shift correlates with the prognosis; less than 5 mm deviation has a good prognosis, whereas a shift of more than 15 mm is related to a poor outcome 4.
What are signs of an uncal herniation
aka descending transtentorial
- ipsilateral hemiparesis (Kernohan’s notch phenomenon)
- ipsilateral pupillary dilation and ptosis from CN3 compression
Marchiafava Bignami
- alcoholics
- edema and T2 bright in corpus callosum (beginning in body, then genu, then splenium); affects central fibers and spares the dorsal and ventral fibers (sandwich sign)
disseminated necrotizing leukoencephalopathy
- seen in leukemia patients getting radiation and chemo
- severe white matter changes, with ring enhancement
- can be fatal
Subcortical Arteriosclerotic Encephalopathy
- aka Binswanger disease
- multi-infarct dementia that only involves white matter
- favors white matter of centrum semiovale
- spares subcortical U fibers
- strong association with HTN
- older patients 55+
CADASIL
Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy
- 40 year old with migraines
- severe white matter disease involving multiple vascular territories in frontal and temporal lobes
- occipital lobes are usually spared
Primary brain tumors that can be multifocal
- lymphoma
- GBM - can be multicentric or can be multiple from seeding
- gliomatosis cerebri
- Medulloblastoma (from seeding)
- ependymoma (From seeding)
- Oligodendroglioma (From seeding
Cortically based tumors
PDOG
- pleomorphic Xanthoastrocytoma
- Dysembryoplastic Neuroepithelial tumor (DNET)
- Oligodendrogliomas
- Gangliogliomas
Pleomorphic Xanthroastrocytoma (PXA)
- ALWAYS supratentorial
- usually involves temporal lobe
- often a cyst with a nodule
- tumor frequently invades leptomeninges
- looks similar to DIG but does not occur in an infant
- occurs at age 10-20
- enhances
https://radiopaedia.org/articles/pleomorphic-xanthoastrocytoma
DNET (Dysembroplastic Neuroepitheilal Tumor)
- kid (<20 yrs) with drug-resistant seizures
- temporal lobe
- focal cortical dysplasia seen in 80%
- little surrrounding edema
- Bubbly lesion; high T2 signal
- does NOT enhance
Oligodendroglioma
- most common in frontal lobe
- calcifies 90%
- expands the cortex
- 1p/19 q deletion - better outcome
- seen in adults (40-50s)
Ganglioglioma
- low grade; can enhance
- can occur at any age
- usually temporal lobe
- cystic and solid mass with focal calcification
Intraventricular tumors - arising from ventricular wall and septum
- ependymoma (kids)
- Medulloblastoma (in kids)
- Subependymal giant cell astrocytoma
- subependymoma (in adults)
- central neurocytoma
intraventricular tumors - arising from choroid plexus
- choroid plexus papilloma
- choroid plexus carcinoma
- xanthogranuloma
What syndromes are associated with medulloblastomas?
- Basal cell nevus
- Turcot’s syndrome
- Gorlin syndrome
Gorlin syndrome
- medulloblastoma
- dural calcification
- basal skin cancer after radiation
- odontogenic cysts
most common intraventricular mass in an adult 20-40 years old
central neurocystoma
Cerebellopontine angle masses
schwannoma (75%)
menignioma
epidermoid
Infratentorial tumors
- AT/RT
- medulloblastoma
- ependymoma
- JPA
- Hemangioblastoma
- ganglioglioma
- Diffuse Pontine glioma
Supratentorial tumors
- Mets
- Astrocytoma
- Gliomatosis cerebri
- oligodendroglioma
- primary CNS lymphoma
hemangiopericytoma
soft tissue sarcoma that can mimic an aggressive meningioma because both enhance homogeneously
- will not calcify or cause hyperostosis
- will invade the skull
signal of blood on MRI
- hyperacute (<24 hours): T1 iso, T2 bright
- acute (1-3 days): T1 iso, T2 dark
- early subacute (3-7 days): T1 bright, T2 dark)
- late subacute (7-14 days): T1 bright, T2 bright)
- chronic (> 14 days): T1 dark, T2 dark)
most sensitive sequence for subarachnoid hemorrhage
FLAIR