Clues to diagnosing culture negative Listeria rhombencephalitis.

A previously healthy 35-year-old Caucasian woman developed left body (including facial) hemianaesthesia, asymmetrical lower cranial nerve palsies and cerebellar signs after a 4-day history of headache, nausea and vomiting. Serial blood and cerebrospinal fluid (CSF) cultures returned negative for a culprit organism. CSF examination revealed a lymphocytic pleocytosis and an elevated protein count. CSF cytological examination identified plasma cells. MRI of brain showed multiple ring-enhancing 'abscess-like' lesions in the brainstem and upper cervical cord together with abnormal meningeal enhancement. A decision was made to treat her empirically for Listeria rhombencephalitis to which she responded completely. CSF PCR eventually returned positive for Listeria monocytogenes. This case illustrates the utility of clinical features, MRI, CSF cytology and PCR in diagnosis and treatment of culture negative L monocytogenes rhombencephalitis in an immunocompetent individual.