HIV encephalopathy
Summary
- HIV-associated neurocognitive disorder with diffuse HIV-related white matter injury
- Imaging clue = symmetric WM change + disproportionate global atrophy.
Clinical
- Subacute cognitive/behavioural slowing ± gait disturbance in advanced HIV
- Typically improves/stabilises with effective ART (but imaging may lag).
Imaging features
MRI
- Symmetric T2/FLAIR hyperintensity in deep/periventricular white matter (centrum semiovale, periventricular regions).
- Relative sparing of subcortical U-fibres (not absolute).
- Diffuse cerebral atrophy often disproportionate for age:
- Sulcal widening + ventriculomegaly (non-obstructive).
- Corpus callosum thinning (supportive, nonspecific).
- No / minimal mass effect.
- No / minimal enhancement.
- DWI: usually no marked restriction.
CT
- Low attenuation in periventricular/deep WM + generalised atrophy; nonspecific but supportive in context.
Key differentials
- PML: tends to be asymmetric, multifocal, U-fibre involvement, ± peripheral DWI “leading edge” restriction; enhancement mainly with IRIS.
- Small vessel disease/toxic–metabolic leukoencephalopathy: consider age/risk factors; usually less “HIV-style” atrophy pattern in young.
Warning
Don’t overcall PML if the pattern is very symmetric with prominent atrophy and little else.
