Progressive brainstem deficits in an immunosuppressed patient

Abstract

Polymerase chain reaction (PCR) testing from the cerebrospinal fluid (CSF) for JC virus, herpes simplex virus 1 (HSV1) and 2, cytomegalovirus and Epstein–Barr virus were negative, however PCR for varicella zoster virus (VZV) was positive. A diagnosis of varicella zoster encephalitis was made. The patient was commenced on high-dose acyclovir and clinical improvement occurred over the subsequent 4 weeks of rehabilitation. The alternative diagnoses for the brainstem encephalitis are unlikely given that the patient showed clinical improvement without therapy targeted at these potential diagnoses. The initial neuroradiological diagnosis was of PML. Negative CSF PCR for the JC virus (or HSV1) does not exclude these diagnoses and a brain biopsy may rarely be required to demonstrate intraparenchymal reproduction of the JC or HSV. However, the patient’s clinical improvement was inconsistent with these diagnoses. Richter syndrome describes the transformation of CLL to diffuse large cell lymphoma. There are rare reports of Richter’s syndrome occurring within the brain in the absence of systemic disease. Brain biopsy is often required for pre-mortem diagnosis; however, the prognosis is poor. Listeria monocytogenes is a food contaminant that is a rare cause of brainstem encephalitis, particularly in the immunosuppressed, as resistance to this intracellular pathogen is cell mediated.