HIV Neurologic Disease

Cryptococcus

• Infection in immunocompromised patients, 2/3 of cases in patients with HIV

  • Seen when CD4 < 100

• Clinical Presentation - Headaches is most common symptom, basically can present with any neuro issues, would suspect in HIV+ pt with new neuro symptoms

• 3 major findings - each affecting a different space

  • Cryptococcomas -

    • Basically small fungus balls - affects parenchyma

    • T1 - hypointense

    • T2 & FLAIR - hyperintense

    • T1 C+ & DWI - varies too much, can see multiple things

  • Meningitis - affects meninges

    • Affects both leptomeninges and pachymeninges

  • Dilation of Peri-vascular spaces

    • Dilation of perivascular spaces allows for them to merge and form large empty spaces that can then form gelatinous pseudocysts

      • These gelatinous spaces are what gives the classic soap bubble finding

    • Can result in infarction

    • T1 - hypointense

    • T2 & FLAIR - hyperintense

    • T1 C+ & DWI - varies too much, can see multiple things

  • Historically - non-enhancing lesions seen -ART drugs were bad - immune system was destroyed

  • Recent times -Enhancing lesions seen - ART drugs are better - immune system can make a comeback

Progressive Multifocal Leukoencephalopathy (PML)

• Multifocal FLAIR hyperintensities

• Caused by JC virus reactivation

• Also seen with natalizumab treatment

• No enhancement

• No associated mass effect

• Different from HIV encephalopathy because HIV encephalopathy will typically be more symmetric but both will not enhance

HSV Encephalitis

• Caused by HSV-1

• Imaging findings

  • Asymmetric lesions, prefers limbic system and temporal lobes

    • Spares basal ganglia (note MCA infarct may look similar but will affect basal ganglia)

  • T1 C+ - patchy enhancement, gyriform enhancement later

  • T2 - cortical/subcortical hyperintensities with white matter sparing

  • DWI - restricted diffusion (may see findings on DWI before other sequences)

• Treatment - IV acyclovir immediately

Neurocysticercosis

• Caused by Taenia solium

• Cystic lesion with dot in the center

• Other presentation is multiple grape like (racemose) lesions clustered together (top right image)

• 4 stages

  • Vesicular (top left)

    • Indicates visible larva

    • Smooth, thin-walled cyst, isodense to CSF, no edema

      • Hyperdense dot within cyst = protoscolex

  • Colloid Vesicular (Middle)

    • Hyperintense cyst with edema

    • Ring enhancing fibrous capsule

    • Indicates Dying larva

  • Granular nodular

    • Healing stage

  • Nodular calcified

    • Healed stage

    • Calcified dot

  • Can have lesions at different stages at same time

• MR spectroscopy

  • ↑ lactate, alanine, succinate, choline

  • ↓ NAA and Cr

Neurosyphilis

• Acute neurosyphilis

  • Leptomeningeal enhancement

  • Syphilic gummas - focal nodules adjacent to meninges -> low T1, high T2, enhance & restrict diffusion, may have dural tail sign

  • Meningomyelitis - long segment T2 hyperintensity, usually in thoracic cord

• Later neurosyphilis

  • Tabes Dorsalis - cord atrophy and T2 hyperintensity of the dorsal columns (difficult to differentiate from SCID)

• Vascular findings

  • Arteritis with concentric wall thickening and possible vascular beading

Basal Meninges Meningitis

• Classically caused by TB

• The other two in the ddx are Sarcoid and Wegeners

Meningitis

• Broad spectrum of shit

IgG4 Pachymeningitis

• Meningitis involving pachymeninges

• Look for concurrent

  • Pancreatitis

  • Salivary gland disease (sialdenitis, dacrocystitis)

  • Orbital pseudotumor

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