Neuroborreliosis Presenting as Encephalitis: A Case Report.

Infection with spirochetes can cause Lyme neuroborreliosis (LNB). Neuroborreliosis presenting as encephalitis is a rare manifestation. We present a 72-year-old male patient hospitalized after three days of confusion and altered mental status. Initial computerized tomography (CT) and magnetic resonance imaging (MRI) of the brain were both unremarkable. Lumbar puncture showed an elevated number of white blood cells, elevated protein, and normal glucose levels in the cerebrospinal fluid (CSF), normal electroencephalogram (EEG), and negative tests for common microorganisms in the CSF. The patient received treatment with acyclovir and ceftriaxone. Lumbar puncture repeated on day 16 showed a decreasing number of white blood cells. A repeated MRI showed white matter edema, interpreted as encephalitis, while a repeated EEG showed signs of a non-specific cerebral lesion. The first lumbar puncture revealed intrathecal immunoglobulin M (IgM) antibodies against  and was positive for DNA using real-time PCR, and the following lumbar puncture showed both IgM and IgG intrathecal antibody production. These results thus confirmed the diagnosis of Lyme encephalitis. The patient improved clinically and was discharged after treatment with ceftriaxone for three weeks. Encephalitis due to LNB should be considered as a differential diagnosis in cases with unexplained neurological symptoms. Changes in MRI and/or EEG might occur late in the course of the disease, underlining the need for repeated tests in unresolved cases.