While the distinction may not always be straightforward,
there are a number of clues which may indicate that the
patient has an infective viral encephalitis rather than a nonviral
encephalopathy. Table 3 summarises the most important
of these and indicates the need for a careful examination
and usually cranial imaging to exclude a structural lesion
followed by CSF examination. These various clues should not
be taken in isolation but considered as a whole to guide the