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ALL / Infectious Diseases

HIV: neurocomplications

HIV: neurocomplications

Focal neurological lesions

Toxoplasmosis
  • accounts for around 50% of cerebral lesions in patients with HIV
  • constitutional symptoms, headache, confusion, drowsiness
  • CT: usually single or multiple ring enhancing lesions, mass effect may be seen
  • management: sulfadiazine and pyrimethamine

toxoplasmosis: CT scan with contrast showing multiple ring enhancing lesions - e Image used on license from Radiopaedia">
Cerebral
Cerebral toxoplasmosis: MRI (T1 C+) demonstrates multiple small peripherally enhancing nodules located predominantly in the basal ganglia as well as the central portions of the cerebellar hemispheres. Only a small amount of surrounding oedema is present. e Image used on license from Radiopaedia
MRI with gadolinium. Multiple ring-enhancing lesions in the deep periventricular area consistent with cerebral toxoplasmosis - e Image used on license from Radiopaedia

Primary CNS lymphoma
  • accounts for around 30% of cerebral lesions
  • associated with the Epstein-Barr virus
  • CT: single or multiple homogenous enhancing lesions
  • treatment generally involves steroids (may significantly reduce tumour size), chemotherapy (e.g. methotrexate) + with or without whole brain irradiation. Surgical may be considered for lower grade tumours

Primary CNS lymphoma: Non-contrast CT demonstrates a hyper-attenuating mass adjacent to the left lateral ventricle, with no calcification or haemorrhage - e Image used on license from Radiopaedia
Primary CNS lymphoma: MRI (T1 C+) demonstrates a large multilobulated mass in the right frontal lobe. It homogeneously enhances and extends to involve the caudate and the periventricular area. There is significant mass effect - e Image used on license from Radiopaedia
MRI T1W with gadolinium. Two lesions are seen in opposite hemispheres that are homogeneous and enhancing, in keeping with primary CNS lymphoma - e Image used on license from Radiopaedia

Differentiating between toxoplasmosis and lymphoma is a common clinical scenario in HIV patients. It is clearly important given the vastly different treatment strategies. The table below gives some general differences. Please see the Radiopaedia link for more details.

ToxoplasmosisLymphoma
Multiple lesions
Ring or nodular enhancement
Thallium SPECT negative		Single lesion
Solid (homogenous) enhancement
Thallium SPECT positive

Tuberculosis
  • much less common than toxoplasmosis or primary CNS lymphoma
  • CT: single enhancing lesion

Generalised neurological disease

Encephalitis
  • may be due to CMV or HIV itself
  • HSV encephalitis but is relatively rare in the context of HIV
  • CT: oedematous brain

Cryptococcus
  • most common fungal infection of CNS
  • headache, fever, malaise, nausea/vomiting, seizures, focal neurological deficit
  • CSF
    • high opening pressure
    • elevated protein
    • reduced glucose
    • normally a lymphocyte predominance but in HIV white cell count many be normal
    • India ink test positive
  • CT: meningeal enhancement, cerebral oedema
  • meningitis is typical presentation but may occasionally cause a space-occupying lesion

Progressive multifocal leukoencephalopathy (PML)
  • widespread demyelination
  • due to infection of oligodendrocytes by JC virus (a polyoma DNA virus)
  • symptoms, subacute onset : behavioural changes, speech, motor, visual impairment
  • CT: single or multiple lesions, no mass effect, don't usually enhance. MRI is better - high-signal demyelinating white matter lesions are seen

HIV-associated dementia (HAD)
  • severe form of HIV-associated neurocognitive disorder (HAND), also called AIDS dementia complex.
  • direct HIV effect on CNS (microglial/macrophage activation, viral proteins) → subcortical dysfunction.
  • features: Cognitive slowing, poor concentration, memory loss + motor dysfunction (clumsiness, gait disturbance) + behavioural change (apathy, depression).
  • diagnosis: Clinical + neuropsych testing; MRI shows cerebral atrophy/white matter changes; exclude opportunistic infections/lymphoma.
  • management: Optimise ART (key), plus supportive care and rehabilitation.
+PassMedicine Notes

Focal neurological lesions

Toxoplasmosis
  • accounts for around 50% of cerebral lesions in patients with HIV
  • constitutional symptoms, headache, confusion, drowsiness
  • CT: usually single or multiple ring enhancing lesions, mass effect may be seen
  • management: sulfadiazine and pyrimethamine
Primary CNS lymphoma
  • accounts for around 30% of cerebral lesions
  • associated with the Epstein-Barr virus
  • CT: single or multiple homogenous enhancing lesions
  • treatment generally involves steroids (may significantly reduce tumour size), chemotherapy (e.g. methotrexate) + with or without whole brain irradiation. Surgical may be considered for lower grade tumours

Differentiating between toxoplasmosis and lymphoma is a common clinical scenario in HIV patients. It is clearly important given the vastly different treatment strategies. The table below gives some general differences. Please see the Radiopaedia link for more details.

Toxoplasmosis_ Lymphoma| Multiple lesions Ring or nodular enhancement Thallium SPECT negative_ Single lesion Solid (homogenous) enhancement Thallium SPECT positive| Tuberculosis
  • much less common than toxoplasmosis or primary CNS lymphoma
  • CT: single enhancing lesion

Generalised neurological disease

Encephalitis
  • may be due to CMV or HIV itself
  • HSV encephalitis but is relatively rare in the context of HIV
  • CT: oedematous brain
Cryptococcus
  • most common fungal infection of CNS
  • headache, fever, malaise, nausea/vomiting, seizures, focal neurological deficit
  • CSF
    • high opening pressure
    • elevated protein
    • reduced glucose
    • normally a lymphocyte predominance but in HIV white cell count many be normal
    • India ink test positive
  • CT: meningeal enhancement, cerebral oedema
  • meningitis is typical presentation but may occasionally cause a space-occupying lesion
Progressive multifocal leukoencephalopathy (PML)
  • widespread demyelination
  • due to infection of oligodendrocytes by JC virus (a polyoma DNA virus)
  • symptoms, subacute onset : behavioural changes, speech, motor, visual impairment
  • CT: single or multiple lesions, no mass effect, don't usually enhance. MRI is better - high-signal demyelinating white matter lesions are seen
HIV-associated dementia (HAD)
  • severe form of HIV-associated neurocognitive disorder (HAND), also called AIDS dementia complex.
  • direct HIV effect on CNS (microglial/macrophage activation, viral proteins) → subcortical dysfunction.
  • features: Cognitive slowing, poor concentration, memory loss + motor dysfunction (clumsiness, gait disturbance) + behavioural change (apathy, depression).
  • diagnosis: Clinical + neuropsych testing; MRI shows cerebral atrophy/white matter changes; exclude opportunistic infections/lymphoma.
  • management: Optimise ART (key), plus supportive care and rehabilitation.


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