What I've Learned About Infectious Diseases
Stroke may be a complication of a CNS infection or a complication of systemic infections or sepsis. Infection is known to cause a hypercoagulable state by increasing concentrations of plasma fibrinogen, beta-thromboglobulin, and anticardiolipin antibodies and to cause increased platelet aggregation. Patients who die of sepsis have elevated levels of plasminogen activator inhibitor type 1, an inhibitor of normal fibrinolysis, as well as decreased levels of the natural circulating anticoagulants, antithrombin III, and protein C. Cerebral ischemia has been reported in patients with hepatitis C virus infection and mixed cryoglobulinemia. Chlamydia pneumoniae infect human vascular endothelial cells and induce procoagulant protein and proinflammatory cytokine expression, the result of which is stroke or myocardial infarction. Cerebral infarction has been associated with Mycoplasma pneumoniae. A number of CNS infections may be complicated by stroke, including bacterial meningitis, VZV infections, tuberculous meningoencephalitis, neurosyphilis, aspergillus, and pediatric HIV infection. Septic emboli from infective endocarditis are a well-known cause of stroke. Cysticercosis is an infection of the CNS caused by the roundworm Taenia solium. The most common manifestation of CNS cysticercosis is epilepsy due to parenchymal brain cysts, but cerebral infarctions may occur due to cysticercotic angiitis.

Consideration should be given to sending any of the following diagnostic studies for infectious diseases in the patient with stroke: blood cultures, complete blood count, enzyme-linked immunosorbent assay for antibody to hepatitis C virus, cryoglobulins, VDRL, HIV serology, acute and convalescent Chlamydia pneumoniae antibody titers, and complement fixation titers for Mycoplasma pneumoniae. Cerebrospinal fluid should be sent for Gram's stain and bacterial culture, acid fast smear, M. tuberculosis culture, M. tuberculosis nucleic acid amplification test, and PCR for HIV RNA, VZV DNA, and varicella-zoster antibodies. In addition to neuroimaging, a chest radiograph (for aspergillus and bacterial pneumonia, including tuberculosis) and transesophageal echocardiography are recommended.