CNS Infection in HIV / AIDS - Differential Diagnosis Framework Principles of HIV-Associated CNS Opportunistic Infections: • Most CNS opportunistic infections result from reactivation of latent pathogens, including PML, toxoplasmic encephalitis, and primary CNS lymphoma. • IRIS might unmask previously unsuspected CNS opportunistic infections when cART is started. • CNS opportunistic infections typically occur when the CD4-cell count is less than 200 cells per μL • Diagnosis should be based on clinical presentation, temporal evolution, CSF, and radiographic features • Multiple infections are present in 15% of cases and some infections might be revealed only after combination antiretroviral therapy is started • Combination antiretroviral therapy should be started, modified, or continued with appropriate antimicrobial therapy • Antimicrobial treatment is generally required until immune recovery (CD4-cell count more than 200 cells per μL) is achieved with antiretroviral therapy Herpes Simplex Virus (HSV): • CD4 Variable • Symptoms: Fever, headache, neck stiffness, vomiting, disorientation, memory loss, dysphasia, depression, confusion, personality change, seizures, visual hallucinations and photophobia • Imaging: Enhancement- Inferomedial temporal lobes, brainstem, cerebellum, diencephalon, and Periventricular regions; associated intracranial hemorrhage • CSF PCR sensitivity 100%, specificity 99-6% Toxoplasmic Encephalitis: • CD4 < 200 • Suspect in movement disorders • Symptoms: Fever, headache, altered mental status, and focal neurologic complaints or seizures • Imaging: - MRI - ring enhancing, Frontal, basal ganglia, parietal - Size lesions < 4cm + mass effect/Edema • Toxoplasma gondii PCR nearly 100% specific and 50-80% sensitive Tuberculous Meningitis: • Variable, but usually CD4 < 200 • Imaging: - Hemorrhage, tuberculomas, or abscesses - <50% show basilar enhancement on CT - Hydrocephalus possible PML: • CD4 < 100 • Demyelinating disease caused by the JC virus • Symptoms: AMS, motor deficits (hemiparesis or monoparesis), limb ataxia, gait ataxia, and visual symptoms such as hemianopia and diplopia • Imaging: periventricular areas and the subcortical white matter. • JC-virus PCR sensitivity variable at 50–90%, but specificity 90–100% Primary CNS Lymphoma: • CD4 < 100 • Symptoms: Confusion, lethargy, memory loss, hemiparesis, aphasia, and/or seizures • Imaging: - Enhancement: multifocal lesions - Periventricular, frontal, cerebellum, temporal - Generally >3 cm diameter - +mass effect/Edema • EBV analysis has a sensitivity of 80–90%, and a specificity approaching 100% for primary CNS lymphoma Cytomegalovirus Encephalitis: • CD4 < 50 • Symptoms: Delirium, confusion, and focal neurologic abnormalities, rapidly progressive encephalopathy. • Imaging: Periventricular Enhancement • PCR >90% sensitive and specific and <25% culture positive Cryptococcal Meningitis: • CD4 <50 • Symptoms: Headache, vomiting, visual changes, hearing loss, palsy of the abducens nerve, and impaired consciousness • Imaging: - Leptomeningeal enhancement, especially in patients with IRIS - Frequently "punched-out" cystic lesions • CSF cryptococcal antigen sensitivity 92% and specificity 83% - sensitivity of serum CrAg testing is comparable to CSF testing Others CNS Infections in HIV: • CNS Syphilis • Aspergillosis • Coccidioidomycosis • Histoplasmosis • VZV • HIV encephalopathy #HIV #CNS #Infections #differential #diagnosis #AIDS #opportunistic #InfectiousDiseases #Neurology
