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IntroductionImmune-mediated encephalitis can occur in the absence of measurable pathogenic antibodies in CSF or serum.Methods and resultsWe present the case of a 29-year-old Sudanese woman presented with four days history of meningism. She is three months post-partum with her fifth child and does not have significant past medical history. She is a current smoker with history of methamphetamine and heroin use until 5 years ago. There were no focal neurological deficits on examination. CT brain was normal and her CSF had 420×106/L leucocytes (Polymorphs 18, Mononuclears 402). Three days later, she deteriorated clinically with GCS 11 and developed left sided hemiplegia requiring intubation and ventilation in intensive care.The CSF culture along with autoimmune encephalitis panel, anti-neuronal antibodies, HSV, VZV, Enterovirus, cryptococcal antigen, TB quantiferon, HIV, Malaria were negative. Her immunology tests were unremarkable including rheumatoid factor, complements, anti-nuclear antibodies, dsDNA, PR3, MPO, RNP, Smith, Ro, La, Scleroderma 70 and Jo-1 antibodies. The MRI Brain showed persistent changes in right hemispheric cortical and subcortical gyriform FLAIR hyperintensities which were also present in DWI images. The EEG showed right temporo-occipital region 7–8 Hz rhythmic discharges with generalised diffuse slowing. She had right parietal lobe brain biopsy which shows perivascular and intramural inflammation by mononuclear cells almost comprised of CD3 T-cells consistent with encephalitis associated with secondary lymphocytic vasculitis. She was treated with intravenous pulsed methylprednisolone and IVIg followed by plasma exchange. Then given high dose oral corticosteroids with slow tapering and intravenous Cyclophosphamide four weekly. Significant neurological improvement noted over next 8 weeks with patient being alert and participating in ongoing multidisciplinary rehabilitation for hemiplegia.ConclusionA case of cerebral biopsy confirmed, CSF and serum antibody-negative encephalitis is presented.

We report a 37-year-old woman with a 2 month history of proximal muscle weakness and extremely high creatine kinase (21,808 U/L) due to necrotizing auto-immune myositis (NAM) in association with anti-synthetase syndrome. Myositis-specific auto-immune antibody panel was positive for anti-Signal recognition particle and anti-PL-12. CT scan of the chest confirmed interstitial lung disease. Prednisolone, intravenous immunoglobulin and cyclophosphamide therapy was given with gradual improvement. This patient is notable for the unusual combination of NAM and anti-synthetase syndrome with the rare finding of two myositis-specific autoantibodies, which directed testing for associated extramuscular features and management with more aggressive immunotherapy.

The anti-synthetase syndrome is a rare, autoimmune multi-system disorder of unclear etiology characterized by a variable combination of inflammatory myositis, interstitial lung disease, Raynaud’s phenomenon and arthritis. Serum autoantibodies to aminoacyl-tRNA synthetase (Anti-PL-12) are often present. The prognosis of the disease is largely determined by the pulmonary involvement. Prednisone with or without azathioprine and methotrexate have been used for myositis, while cyclophosphamide should be considered for severe pulmonary involvement. Anti SRP associated necrotizing autoimmune myositis is part of the spectrum of autoimmune inflammatory myopathies. It is characterized by the presence of signal recognizing particle antibodies which may occur in isolation or in some cases, in conjunction with other serum auto-antibodies. We describe a rare and interesting case of a 37 year old female who presented with a progressive proximal muscle weakness involving the upper and lower limbs in association with lethargy. She also displayed Raynaud’s phenomenon and complained of exertional shortness of breath. She had extremely high creatine kinase levels (22,000) U/L and electrophysiological confirmation of an active myositis. She had positive anti SRP antibodies and muscle biopsy findings of a necrotizing autoimmune myositis. In addition, she had anti-PL-12 antibodies and evidence of interstitial lung disease on pulmonary function tests and CT lung imaging. Her constellation of symptoms, signs and investigative findings were consistent with an anti-synthetase syndrome. She was treated initially with methylprednisone, azathioprine and IVIG without significant improvement. Her myositis and ILD partially responded to IV cyclophosphamide therapy. This case demonstrates a unique patient with anti-synthetase syndrome in association with anti-SRP and anti-PL-12 myositis specific antibodies. It highlights the use of myositis-specific antibody testing in assisting the diagnosis and choice of therapy. Further studies are required to determine the occurrence of multiple myositis specific antibodies in necrotizing myopathies and if their presence correlates with prognosis and treatment response.