HIV- CNS manifestations

Today we discussed the approach to neurological symptomatology in the setting of HIV.

As a general rule, whenever faced with a new (or worsened) problem in the setting of a pre-existing disease, a useful dichotomy is whether this new problem is related or unrelated to the underlying disease.


A useful way of subdividing this problem is whether or not there are imaging abnormalities (may require enhanced MRI to see), and if so, whether there is mass effect.

CNS lesion with mass effect:
1) Toxoplasma (in CD4 <100). Reactivation from prior infection. Toxo antibodies are supportive. Lesions are multiple, and localized to frontal or parietal lobes, thalamus, basal ganglia. Ring enhancement in 90%. Shown in the above picture. May be mimicked by lymphoma- MRI is best test.
2) Primary CNS lymphoma. May see neuro sx or wasting sx. Solitary and multiple lesions are equally frequent. Corpus callosum lesions or periependymal lesions are more likely lymphoma.
3) Brain abscess (staph, strep, salmonella, aspergillus, listeria, 'gumma' from syphillis) Rarely, tuberculoma or cysticercosis

CNS lesion without mass effect:
1) PML- demyeliniting disease from JC virus (acquired in childhood by 90% of population). Seen in severe immunosuppression. Rapidly progressive focal deficits inc. hemiparesis, field deficits, ataxia, aphasia, cognitive changes. Multifocal demyelination.
2) CMV encephalitis- need CD4<50. delirium, confusion, neurological abnormalities.
3) HSV encephalitis- increased risk in HIV; may see temporal lobe changes on MRI
4) HIV encephalopathy: memory and psychomotor slowing, depression, movement disorders- may see symmetric MRI lesions

No CNS lesion on imaging:
1) Bacterial meningitis- esp S. pneumo, listeria
2) TB meningitis
3) Cryptococcal meningitis- need to send CSF and serum crypto antigen.
4) Neurosyphillis

Brain biopsy is gold standard, and is sometimes required to differentiate above possibilities (esp. lymphoma vs. toxoplasmosis)

Some tests you might order from a lumbar pucture in this setting in addition to routine:
Fungal cultures, AFB staining
PCR for JC virus, HSV, EBV, TB ('AMTD')
Cryptococcal antigen
VDRL
Check opening pressure; may be high in cryptococcal meningitis. High OP in cryptococcal meningitis carries a poor prognosis, and may require a lumbar drain or shunt.

Link:
Click here for a good review of PML from the ID department