Pontomedullary encephalitis and basal meningitis due to Listeria monocytogenes: report of a case.

A case of CNS listeriosis in a 49-year-old man, previously in good health, is described. The illness showed a biphasic clinical pattern with a prodromal phase characterized by headache, fever and leukocytosis and subsequent development of pontomedullary cranial nerve paresis. The infection was rapidly progressive and fatal. Gram-positive rods, identified as Listeria monocytogenes, were detected in CSF samples only at the end stage of illness. Neuropathological abnormalities consisted of rhombencephalitis and basal meningitis. The major difficulties encountered in the early diagnosis of CNS listeriosis are discussed.