Clinical/Scientific Notes

We report a case of varicella-zoster virus (VZV) mye-litis in a woman with relapsing-remitting multiplesclerosis(RRMS)receivingnatalizumab,ahumanizedmonoclonal antibody that induces an immunosup-pression localized to the CNS.Case report. A32-year-oldwomanwastreatedwithna-talizumab for highly active RRMS. After the fourth infu-sion, she complained of a right radicular pain in a L5/S1territory.Afewdayslater,theneurologicexaminationdis-closed a distal weakness (3/5 Medical Research Council[MRC]) in the right leg with signs of pyramidal irritationsuggestingaspinalcordrelapse.ThespinalcordMRIdis-closed focal cervical and dorsal T2 hyperintensities and aT2 hypersignal in the conus region with contrastenhancement (figure). A spinal cord relapse was consid-ered. HighdosesofIVmethylprednisolonewereinitiatedfor3days.Twoweekslater,thepatientdeteriorated,withan increase of leg weakness (2/5 MRC) and bladder dys-function. She received another series of IV methylpred-nisolone for 3 days, without improvement. Because ofthis unusualevolution, weperformedalumbar puncture,which revealed a lymphocytic pleocytosis (18 elements),normal proteins, and glycorrhachia. VZV DNA detectedby PCR amplification was positive in CSF. Cytomegalo-virus and herpes simplex virus (HSV) PCR in the CSFwere negative. HIV screeningwasnegative.VZVimmu-noglobulin G in the blood was positive before this acuteepisode (tested in January 2012). No skin rash was notedor reported by the patient. A second spinal cord MRIshowed progression of lesion size, persistent contrastenhancement in the conus region, and new contrast en-hancementsindorsallesions(figure).AcuteVZVmyelitiswas diagnosed. The patient was treated with IV acyclovir10 mg/kg/8 h for 3 weeks and then switched to valacy-clovir, which resulted in a c linical improvement (4/5MRC in right lower limb and recovery of subnormalbladder function but persistent sensory loss in the leftlower limb). CSF at 1 month was normal (4 elements,negative VZV PCR). Spinal cord MRI at 2 months wasclearly improved (figure). Natalizumab was discontinued.Discussion. If cases of HSV encephalitis and meningi-tis have been previously reported,