Detection of varicella-zoster virus DNA during medullary and brainstem relapses in multiple sclerosis.

We describe three cases of patients with concomitant acute medullary or brainstem multiple sclerosis (MS) lesions and detectable spinal fluid varicella-zoster virus DNA. Herpes simplex virus PCR was also positive in two of the patients. One patient was re-punctured 2 weeks following the relapse, with negative results. The PCR findings greatly delayed correct diagnosis and treatment in all three patients. Based on our cases, we propose that inflammatory medullary and brainstem lesions could result in viral leakage, and possibly viral reactivation, from destroyed sensory neurons, yielding false-positive cerebrospinal fluid PCR results. As this can have diagnostic and therapeutic consequences, further studies are warranted to evaluate the clinical relevance of these findings. 2016 BMJ Publishing Group Ltd.