Brain Flashcards
Pott puffy tumour:
- DDx?
- Complications?
- Treatment?

- DDx of a hypodense expansile process exiting the sinus:
- mucocele
- infection
- lymphoma
- primary sinus neoplasm, e.g., SCC
- mucinous mets
- Complications:
- Dural sinus thrombosis
- Abscess in the frontal lobes
- meningitis
- cerebritis
- subdural empyema
- Tx: surgical drainage w/6 wks IV abx.
- Other points:
- Presents as an abruptly forming forehead mass emanating from the frontal sinus.
- 9:1, M:F
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In patients over the age of 30, what is the prevalence of pineal calcification on CT scans?

50%
- The prevalences of pineal and choroid plexus calcifications are correlated. Patients with pineal calcification are 4x as likely to have choroid plexus calcifications compared with individuals who demonstrate no pineal calcification.
What do the arrows indicate on this axial T1WI?

Superior cerebellar peduncles.
This image is obtained through the upper pons. The structures indicated by the arrow form the lateral borders of the upper part of the 4th ventricle and are the superior cerebellar peduncles.
Where is choroid plexus located & in what horns is it not?
Lateral ventricles: temporal horns, but NOT occipital.
Roof of 3rd.
Fourth.

Dx?
- Unusual manifestation of these?

Oligodendroglioma: peripherally cortical mass w/heterogeneous enhancement & calcs.
- Intraventricular location-3-8%.
- Calcs in 20-90%.
- Most commonly, heterog enhancement.
- Most commonly peripheral, frontal lobe.
- Vasogenic edema is not as common as with higher glade astros or mets.
- If it has a 1p/19q deletion then it has a better outcome.
List the stages of active neurocysticercosis infection in order (earliest to latest).

VCGC: vesicular, colloidal, granular nodular, calcified nodular
Vesicular: the larva lodges in a capillary & forms a cyst to protect the larva (like the initial, vesicle stage of cold sores, the vesicles form first and are full of the pathogen).
- This form can remain in the brain for years until there is host response and inflammation which can cause seizures.
Colloidal: this is when the scolex dies, it begins to degenerate & leak antigens, then inflammation begins, & edema surrounds the cyst. (Think “collision” with the immune system.)
Granular nodular: as the inflammatory response decreases, there is less edema, but thin rim enhancement persists, surrounding the more proteinaceous cyst.
Calcified nodular: inactive, calcified cyst, like a calcified granuloma.

In neurocysticercosis, which imaging characteristic has been postulated to be helpful for determining the death of a scolex?
Central dot of diffusion restriction, corresponding to the scolex.

What is the most common primary brain tumour in adults?
- Astrocytoma/glial neoplasm.
- These account for 15% of all intracranial primary neoplasms.

Dx? Surveillance MR for a known condition.

vHL: endolymphatic sac tumour & hemangioblastomas.
Most common primary brain tumour of the posterior fossa in adults?
Hemangioblastoma
- 70% of the time you’ll see flow voids in the periphery of the cyst.
- 90% are found in the cerebellum.
- Associated w/polycythemia.

If I say posterior fossa cyst w/a nodule in peds you say…
Juvenile pilocytic astrocytoma
- WHO grade 1, but the nodule will enhance (the exception to the low grade/no enhancement rule).

Dx, DDx?

Vestibular schwannoma: CP angle mass w/o restriction, trumpet-shaped, expanded IAC.
-
DDx:
- Meningioma: 15% of all IAC masses; strongly enhance as it’s extradural; will restrict as it’s highly cellular, w/dural tail & show hyperostosis; more common in women.
- Epidermoid: 5% of all; follows CSF appearance on CT/MR & restricts; peripheral enhancement, if any.
- Neurofibroma: rare as a primary intracranial lesion even in NF-1.
Most common CP angle mass?
Vestibular schwannoma
- 85% of all CP angle masses.
- Most commonly involve inferior division vestibular nerve (CN VIII).
- Most schwannomas occur along sensory nerve fibers, CN8 is the most common, followed by trigeminal nerve.
- <20% are associated w/NF-2.
- Pts commonly present w/hearing loss, but can also have vertigo, imbalance.

Dx?

Ependymoma: 4th vent, heterogeneous, toothpaste-like tumour squeezing through the foramen magnum.
- Originate from ependymal cells of ventricles.
- 70% from 4th vent & often extend into foramen of Luschka & Magendie.
- Bimodal: 6yo & smaller peak at 30yo.
The most common intraventricular mass in an adult?
Central neurocytoma
- 20-40yos
- Swiss cheese appearance, but calcify a lot.
- Most commonly in the lateral ventricle, attached to the septum pellucidum or ventricular wall.
- WHO grade II.

Dx?

Epidermoid cyst: follows CSF, but restricts.
DDx: arachnoid cyst.
- 40-50% occur in the CPA.
- Also seen in 4th vent, sellar region & less commonly intraparenchymal.
- Can be hyperdense on CT due to protein content (white epidermoid).
Primary CNS lymphoma is usually of what cell type?

- Large B-cell.
- Over 50% solitary.
- Solid, uniformly enhancing & restricting lesion.
- Like to abut the CSF surface.
- Periventricular & CC are the most common locations, followed by BG & thalami.
Dx:? 20yo male w/Hx of drug-resistant seizures.

DNET: temporal lobe, bubbly/cheesy, expansile cortical lesion which does not enhance.
Dx? 20yo.
- From where, exactly, is this originating?
- Next step?
- What to look for intracranially, and if seen, what is the association?

Medulloblastoma: homogeneously enhancing, restricting, projecting into 4th vent.
- Roof of 4th ventricle/vermis.
- Image the spine as these love to drop met: Zuckerguss.
- Dural calcs = Gorlin syndrome.
- Gorlin: basal cell cancer after radiation & odontogenic cysts.

Dx: pt w/TS?
- From what structure is this arising?
- What helps to differentiate these from subependymal nodules, also seen w/TS?

SEGA (subependymal giant cell astrocytoma): homogeneously enhancing, >1cm mass.
- Lateral wall of ventricle near the foramen of Munro.
- SEGAs grow.
- These can calcify.
- Occur in 15% of TS pts.
Which segment of the facial nerve most commonly exhibits physiologic enhancement?

The tympanic segment.

Dx?

Bell’s palsy: enhancing meatal & labyrinthine segment of the L facial nerve.
- Acute peripheral nerve paralysis of unknown cause.
- HSV reactivation is the most commonly proposed mechanism.
What is the most commonly involved cranial nerve in CNS Lyme disease?
CN 7, facial. Unilateral involvement is more common.
How common is isolated neurosarcoidosis w/o systemic manifestations of it?

<1%
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