Overview of CNS Infections General Considerations Classification : Infectious diseases can be classified into congenital/neonatal and acquired infections. They can be further subdivided by etiology, i.e., bacterial, viral, fungal, parasitic, and rickettsial diseases. Infectious diseases can have different manifestations depending…
KEY FACTS Terminology Cerebrospinal fluid (CSF)-filled parenchymal cavity Deep, unilateral/bilateral cavity/excavation Usually communicates with ventricle &/or subarachnoid space Lined by reactive gliosis/astrocytic proliferation Congenital (perinatal brain destruction) or acquired (trauma, infection, etc) Imaging Best diagnostic clue: CSF-filled cavities with enlarged…
KEY FACTS Terminology Choroid plexus cysts (CPCs) Nonneoplastic, noninflammatory cysts Contained within choroid plexus; lined by compressed connective tissue Imaging General Typically in atria of lateral ventricle Usually small (2-8 mm) Rare: Large cysts (> 2 cm) Usually multiple, often…
KEY FACTS Terminology Nonneoplastic intrapineal glial-lined cyst Imaging CT Sharply demarcated, smooth cyst behind 3rd ventricle 80% < 10 mm (can be large; reported up to 4.5 cm) Fluid iso-/slightly hyperdense to cerebrospinal fluid (CSF) 25% Ca++ in cyst wall…
KEY FACTS Terminology Perivascular spaces (PVSs) Also known as Virchow-Robin spaces Pial-lined interstitial fluid-filled structures Accompany penetrating arteries Do not communicate with subarachnoid space Imaging Clusters of variably sized, well-delineated nonenhancing cysts PVSs occur in all locations, at all ages;…
KEY FACTS Terminology Synonyms: Hippocampal remnant cyst, hippocampal sulcal cavities Cyst or string of cysts along residual cavity of primitive hippocampal sulcus Imaging String of cysts along lateral margin of hippocampus Cysts follow cerebrospinal fluid signal on all MR sequences…
KEY FACTS Terminology Intracranial epidermoids: Congenital inclusion cysts Imaging Cerebrospinal fluid-like mass that insinuates cisterns and encases neurovascular structures Morphology: Lobulated, irregular, cauliflower-like mass with “fronds” FLAIR: Usually does not suppress completely DWI: Diffusion hyperintensity definitively distinguishes from arachnoid cyst…
KEY FACTS Terminology Benign, ectopic, squamous epithelial cyst containing dermal elements, including hair follicles and sebaceous and sweat glands Imaging Midline unilocular cystic lesion with fat Subarachnoid fatty droplets if ruptured Suprasellar or posterior fossa most common intracranial sites Extracranial…
KEY FACTS Terminology Unilocular mucin-containing 3rd ventricular cyst Imaging > 99% are wedged into foramen of Monro Pillars of fornix straddle, drape around cyst Majority are hyperdense on NECT Density correlates inversely with hydration state MR signal more variable Generally…
KEY FACTS Terminology Intraarachnoid cerebrospinal fluid (CSF)-filled sac that does not communicate with ventricular system Imaging General findings Sharply demarcated round/ovoid extraaxial cyst Isodense/isointense with CSF Location Middle cranial fossa (50-60%) Cerebellopontine angle (10%) Suprasellar (10%) Miscellaneous (10%) (convexity, quadrigeminal)…