Abstract

Neuroimaging plays a crucial role in the diagnosis in infectious diseases of the central nervous system. The review summarizes top 10 important things to know in the imaging diagnosis of infectious diseases of the central nervous system. 1. Herpes simplex virus encephalitis. MR image shows high signal in the temporal lobes, insulae, and cingulate gyri bilaterally on T2-weighted images, FLAIR images and diffuse weighted images. 2. Varicella-zoster virus (VZV)infection. MR images shows multiple focal high signal intensities in cerebral cortices and white matters especially peri-ventricular areas on T2-weighted images. VZV vasculopathy causes cerebral arteries occlusion resulting in cerebral infarctions and rarely hemorrhages. 3. Japanese encephalitis. Bilateral thalamic and nigral involvement is classical MR imaging. Other areas may be involved are pons, cerebellum, basal ganglia, cerebral cortex and spinal cord. 4. Influenza encephalopathy includes acute necrotizing encephalopathy, acute brain swelling encephalopathy, hemorrhagic shock and encephalopathy syndrome (HSES), Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), mild encephalitis/encephalopathy with a reversible splenial lesion (MERS). 5. progressive multifocal leukoencephalopathy (PML)shows asymmetric periventricular and subcortical white matters, brainstem and cerebellar white matters involvement. Lesions show T1 and T2 prolongation and sometimes diffusion restriction. 6. human immunodeficiency virus encephalopathy/encephalitis shows symmetric cerebral white matter T2 prolongation. 7. Cerebral abscess and subdural empyema shows diffusion restriction on diffusion weighted images and are critical for the diagnosis. Bacterial meningitis shows meningeal enhancement on post gadolinium T1-weighted images. 8. The neuroimaging characteristics of tuberculous meningitis classically include leptomeningeal and basal cisternal enhancement, ventriculomegaly due to hydrocephalus, periventricular infarcts, and the presence of tuberculomas. 9. Neurosyphilis shows cerebral and meningovascular involvement and appears T2 prolongation and meningeal contrast enhancement. Syphilitic gummas appear as small focal nodules adjacent to the meninges and shows homogeneous contrast-enhancement. 10. cerebral sparganosis mansoni typically shows tubular enhancement in a linear or curvilinear fashion-the tunnel sign-on post gadolinium T1-weighted images