To highlight the diagnostic pearls to properly recognize CNS infections. To showcase the differential diagnosis of the main CNS infections. To provide a pictorial review with the most typical findings of common and uncommon infections, ranging from bacteria, to viruses, fungi and parasites.

CNS infections are a rather serious condition, with high morbimortality. Early diagnosis is key to a good prognosis.There are many radiological appearances.Through clinical cases, we will cover the most important radiological manifestations of CNS infections.

1) MENINGITIS Most do not show any remarkable findings. In any case, MRI is more sensitive. When present, the most common is leptomeningeal enhancement(Fig. 1), which ought to be distinguished from pachymeningeal enhancement (Fig. 2). There are some others (Fig. 3): presence of purulent exudate in the subarachnoid space. signs of expansivity. a slight dilatation of the ventricular system. acute sinusitis, otitis media, mastoiditis and/or petrositis. Complications of acute meningitis: Acute hydrocephalus: may be communicating, as described above, or non communicating (Fig. 4). Empyemas: can...

Most of the meningitis do not show remarkable findings. If they do, the most frequent are: leptomeningeal enhancement, presence of purulent exudate in the subarachnoid space, effacement of brain sulci and basal cisterns and incipient dilatation of the ventricular system. The main complications of acute meningitis are: acute hydrocephalus, extra-axial collections, cranial nerve involvement, venous infarcts, arterial ischemic infarcts secondary to vasculopathy, ventriculitis and extension to the cerebral parenchyma. Pyogenic brain abcesses typically show contrast uptake in the peryphery, diffusion restriction in the cavity, dual...

D. Castanedo Vázquez: Nothing to disclose E. Marco de Lucas: Nothing to disclose R. Sutil-Berjón: Nothing to disclose E. Marín Díez: Nothing to disclose M. Drake Perez: Nothing to disclose J. García Poza: Nothing to disclose S. Revuelta Gómez: Nothing to disclose Á. Sánchez Mulas: Nothing to disclose

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