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Background: Neuromyelitis optica (NMO) is a demyelinating disorder involving optic neuritis and transverse myelitis. The various associations with disorders as Sjogren?s disease, systemic lupus erythematosus, antiphospholipid syndrome, viral infections, tuberculosis or vaccination were described. Human herpesvirus 6 (HHV6) is a neurotropic virus causing severe central nervous system infection after reactivation of latent HHV6 in immunocompromised individuals. We report the case of 58-year old woman with NMO and high HHV6 DNA load detected by polymerase chain reaction (PCR) in cerebrospinal fluid (CSF) questioning the potential relationship. Case report: 58-year old woman reported progressive visual loss, concentric reduction of the visual fields since November 2009. Opthalmological examination discovered optical nerve atrophy and visual evoked potential P100 wave prolongation bilaterally. MRI brain scan showed two small T2-hyperintense lesions in frontal lobes and in CSF examination were mild mononuclear pleocytosis (5,6/1mcL mononuclear cells) and normal total protein content 0,32mg/l. Antinuclear and anti-DNA antibodies were negative. When admitted to hospital the clinical pattern involved subjective complaints as paresthesias of lower extremities, headache, vertigines and objectively gait ataxia in April 2010. Subsequent CSF examination confirmed neuroinflammation (mixed pleocytosis; 55 mononuclear cells/1mcL, 41 polynuclear cells/1mcL and total protein content 1,2mg/l), 2 IgG oligoclonal bands in serum and CSF. Viral HHV6 DNA load was detected by PCR. Treatment with intravenous acyclovir, improved CSF findings, (mild pleocytosis; 23 mononuclear cells/1mcL, normal total protein content 0,37 mg/l). In spite of this improvement patient developed severe palsy of lower extremities during 2 days. MRI scan of thoracic spinal cord showed demyelinating lesions from C7 to Th5 area. Corticosteriod therapy was unsuccessful. The positivity of anti-aquaporin 4 antibodies were confirmed by immunohistochemistry and ELISA tests. Clinical pattern, MRI scans and antibodies confirmed the diagnosis of neuromyelitis optica Devic according to current valid criteria. Conclusions: We report an association between HHV6 infection and NMO for the first time. As the late primary infection with HHV6 might be associated with multiple sclerosis we cannot exclude such a role of HHV6 virus in other demyelinating diseases including neuromyelitis optica Devic.

Read More: Neuromyelitis optica Devic and concomitant human herpesvirus-6 neuro-infection: is a role for causal relationship? A case report