{
  "abstract": "We report a 50 year-old civil engineer with progressive tremulousness, dyscognitive symptoms, temperatures, constipation, erectile dysfunction, fatigue and weight loss over two months, followed by acute painful left-eye vision loss.Examination was significant for left-eye superior altitudinal defect, red desaturation, and relative afferent pupillary defect. Fundoscopy was normal. There was a jerky irregular symmetrical distal upper-limb postural and kinetic tremor accompanying action- and stimulus-sensitive myoclonus. Head retraction reflex and exaggerated startle responses were present. There was global spreading hyperreflexia but normal tone, power and sensation. MMSE was 25/30 with losses for orientation, attention and recall.Blood tests were normal. CSF examination demonstrated monocytic lymphocytosis(70x10^6/L) and elevated protein(1.82g/L) and neopterins(604nmol/L). Broad infectious screening and flow cytometry were normal. Serial limbic encephalitis, antineuronal, GlyR, MOG, AQP4 antibodies and tissue-based assay for anti-GFAP astrocytopathy were negative. Tremor-study indicated subcortical myoclonus. MRI revealed left optic neuritis, extensive myelitis and contrast-enhancing perivenular subcortical disease radially oriented from the lateral ventricles and corpus callosum resembling anti-GFAP astrocytopathy. PET was normal.He responded clinically and radiologically to pulse methylprednisolone and plasma exchange. Two months later he suffered relapse with bladder dysfunction and gait impairment which again responded to steroids and plasma exchange. Rituximab was added.This case expands the spectrum of movement disorder-presenting steroid-responsive CNS autoinflammatory disease, emphasising seronegative case recognition. Myoclonus may be an initial manifestation of autoimmune encephalitis (CASPR2, GABABR, GlyR, DPPX, IGLON5, GFAP).1 Anti-GFAP astrocytopathy is a radiological differential, although the pathogenicity of anti-GFAP antibodies is questionable and seronegative cases are increasingly reported.2 3 References Govert F, Leypoldt F, Junker R, et al. Antibody-related movement disorders – a comprehensive review of phenotypye-autoantibody correlations and a guide to testing. Neurol Res Pract. 2020;20(2):6.Guo Y, Endmayr V, Zekeridou A, et al. New insights into neuropathology and pathogenesis of autoimmune glial fibrillary acidic protein meningoencephalomyelitis. Acta Neuropathol. 2024;147:31.Azzolini F, Farina A, Barilaro A, et al. An emerging spectrum of autoimmune astrocytopathy: beyond anti-GFAP antibodies. J Neurol Sci. 2021;429:117816.",
  "authors": [
    {
      "affiliations": [
        "Neurology Department, Westmead Hospital, Sydney, NSW, Australia",
        "Sydney Medical School, University of Sydney, Sydney, NSW, Australia"
      ],
      "name": "Matthew Georgiades"
    },
    {
      "affiliations": [
        "Neurology Department, Westmead Hospital, Sydney, NSW, Australia",
        "Sydney Medical School, University of Sydney, Sydney, NSW, Australia"
      ],
      "name": "Niroshan Jeyakumar"
    },
    {
      "affiliations": [
        "Neurology Department, Westmead Hospital, Sydney, NSW, Australia",
        "Sydney Medical School, University of Sydney, Sydney, NSW, Australia"
      ],
      "name": "Ross Penninkilampi"
    },
    {
      "affiliations": [
        "Neurology Department, Westmead Hospital, Sydney, NSW, Australia",
        "Sydney Medical School, University of Sydney, Sydney, NSW, Australia"
      ],
      "name": "Hugo Morales-Briceno"
    },
    {
      "affiliations": [
        "Neurology Department, Concord Repatriation General Hospital, Sydney, NSW, Australia",
        "Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia"
      ],
      "name": "Shadi El-Wahsh"
    },
    {
      "affiliations": [
        "Neurology Department, Westmead Hospital, Sydney, NSW, Australia"
      ],
      "name": "Ainhi Ha"
    },
    {
      "affiliations": [
        "Neurology Department, Westmead Hospital, Sydney, NSW, Australia",
        "Sydney Medical School, University of Sydney, Sydney, NSW, Australia"
      ],
      "name": "Justin Garber"
    }
  ],
  "title": "3634 A seronegative shakedown: steroid-responsive encephalomyelitis and optic neuritis presenting with myoclonus, encephalopathy and vision loss",
  "uid": "9d462008-2be0-5e4e-9d3c-20676305d0db"
}