KEY FACTS Terminology Opportunistic infection Caused by parasite Toxoplasma gondii Most common opportunistic CNS infection in AIDS Imaging CT Ill-defined, hypodense lesions and edema Basal ganglia, thalamus, cerebellum Rim, nodular, target enhancement MR T2 hypointense T1 C+ target sign highly…
KEY FACTS Terminology HIV-1 encephalitis/HIV-1 encephalopathy HIV-associated neurocognitive disorders Imaging CT Atrophy Bilateral periventricular/diffuse WM hypointensities Basal ganglia, cerebellum, brainstem hypodensity MR Diffuse “hazy” hyperintense WM on T2/FLAIR Nonenhancing (if enhancement present, consider opportunistic infections, immune reconstitution inflammatory syndrome) Pathology…
KEY FACTS Terminology Lyme disease, Lyme neuroborreliosis (LNB) Multisystem inflammatory disease Caused by spirochete Borrelia burgdorferi (USA) Transmitted by Ixodes tick bite Reservoirs = white tail deer/field mouse Imaging MS-like white matter (WM) lesions (may enhance) 2-8 mm (large “tumefactive”…
KEY FACTS Terminology Intracranial parasitic infection caused by pork tapeworm Taenia solium 4 pathologic stages: Vesicular, colloidal vesicular, granular nodular, and nodular calcified Imaging Best diagnostic clue: Cyst with “dot” inside Convexity subarachnoid spaces most common location Inflammatory response around…
KEY FACTS Terminology Typically causes tuberculous meningitis &/or localized CNS infection, tuberculoma Imaging Basilar meningitis + extracerebral TB (pulmonary) Meningitis + parenchymal lesions highly suggestive Tuberculomas Supratentorial parenchyma most common Usually T2 hypointense Enhances strongly (solid or ring enhancing) Tuberculous…
KEY FACTS Terminology Acute cerebellitis Imaging Bilateral cerebellar hemispheric gray and white matter low attenuation (NECT), T2/FLAIR hyperintensity (MR); unilateral involvement less common Confluent regions of T2 prolongation, affecting gray and white matter ± pial or subtle parenchymal enhancement DWI/ADC…
KEY FACTS Terminology Diffuse brain parenchymal inflammation caused by variety of pathogens, most commonly viruses Location dependent on etiology Imaging Abnormal T2 hyperintensity of gray matter ± white matter or deep gray nuclei Large, poorly delineated areas of involvement common,…
KEY FACTS Terminology West Nile virus (WNV), West Nile fever, West Nile neuroinvasive disease Mosquito-transmitted acute meningoencephalitis Imaging Head CT usually normal MR with DWI, T1 C+ Classic: Bilateral basal ganglia, thalamic hyperintensity Patchy, poorly demarcated hyperintense foci in cerebral…
KEY FACTS Terminology Encephalitis caused by human herpes virus 6 (HHV-6) Imaging Immunocompromised patient with abnormal signal medial temporal lobe(s) Limbic system: Hippocampus, amygdala, parahippocampal gyrus Insular region, inferior frontal lobe involvement less common than herpes simplex encephalitis Atypical pattern…
KEY FACTS Terminology Brain parenchyma infection caused by herpes simplex virus type 1 (HSV1) Typically reactivation in immunocompetent patients Imaging Best imaging clue: T2/FLAIR hyperintensity of limbic system (medial temporal and inferior frontal cortex) with DWI restriction Typically bilateral disease,…