Before HAART about 10% of AIDS patients in developed countries presented with neurological opportunistic infections and malignancies, but these presentations are now less common. Peripheral neuropathy is still common as a complication of therapy. Patients with advanced HIV infection may present with diffuse encephalopathy directly as a result of HIV infection itself (“AIDS dementia”). Less common causes of this clinical picture include cytomegalovirus, herpes simplex virus (HSV) and rarely toxoplasmosis. Focal cerebral disease is commonly caused by toxoplasmosis, cerebral lymphoma or progressive multifocal leucoencephalopathy. Characteristic CT and MRI appearances usually allow these to be distinguished. In the case of a presumptive diagnosis of toxoplasmosis a therapeutic trial of anti-toxoplasma therapy should be given before brain biopsy is considered. Rare causes of focal cerebral lesions include tuberculosis, cryptococcosis, candidosis, HSV and varicella-zoster virus. Mild CSF lymphocytosis and moderate elevation of CSF protein are common in HIV patients at all stages of infection. Bacterial meningitis is uncommon, but cryptococcal meningitis is common, particularly in patients from Africa.
