Intracranial inflammatory and infectious diseases

Question 1

Meningitis localizations

Answer 1

Can be local around an external infection or puncture point.

Spreads along the cisterns, subarachnoid space, along the sulci

Question 2

Meningitis signs, lab values

Answer 2

Increased ICP
Increased protein content
Leukocytes in the CSF, neutrophils for bacterial, lymphocytes for viral or fungal/TB.

CSF glucose is DECREASED. in bacterial or fungal meningitis, normal in viral.

Question 3

Meningitis radiology

Answer 3

Radiology can be totally normal,

Ventricles may expand

Higher than usual contrast enhancement, extending down into the brain sulci on both CT sand MRI.

Question 4

Abscesses

Answer 4

hematogenously spread abscesses usually occur in multiple

parasitic abscesses, echinococcus,
hydatid cysts.

perifocal edema around the abscess.
ring enhancing.
cystic contents hypodense.

Question 5

TB

Answer 5

Tuberculous meningitis - The more common form
Thick tuberculous exudate within the subarachnoid space, particularly pronounced at the base of the brain (especially in the interpeduncular fossa, anterior to the pons and around the cerebellum) and may also extend into the Sylvian fissures
Commonly causes obstructive hydrocephalus
Can also compress/occlude arteries and cause infarcts in 1/3 of cases.

Pachymeningeal TB - Dura mater specifically thickening.
Intraparenchymal TB.

Intra-parenchymal tuberculoma: typically appear as ring-enhancing lesions with surrounding vasogenic oedema. Centrally they tend to have only intermediate or even low signal on T2 weighted images (helpful in distinguishing them from the less common tuberculous abscess)

Question 6

Demyelinating diseases, what imaging to use

Answer 6

MRI.

Demyelinating lesions have hyperintense T2, PD, and FLAIR signals.

Remember normally on T2 images the white matter is dark, so hyperintense lesion in the T2 white matter stand out.