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G400(P) Two cases of mild encephalopathy with a reversible splenial lesion (MERS)
  1. A Awad1,
  2. S Avula2,
  3. C DeGoede3,
  4. P Nair3,
  5. K Rakshi4,
  6. A Iyer2,
  7. R Kneen2,5
  1. Medical Sciences Division, University of Oxford, Oxford, UK
  2. Littlewoods Neurosciences Unit, Alder Hey Children’s NHS Foundation Trust, Liverpool, UK
  3. Royal Preston Hospital, Lancashire Teaching Hospitals NHS Foundation Trust, Preston, UK
  4. Royal Blackburn Hospital, East Lancashire Hospitals NHS Trust, Blackburn, UK
  5. Institute of Infection and Global Health, University of Liverpool, Liverpool, UK

Abstract

Introduction Mild Encephalopathy with Reversible Splenial lesion (MERS) is a newly-proposed clinical-radiological para/post infectious syndrome characterised by an acute, transient encephalopathy and radiological evidence of a reversible lesion in the splenium of the corpus callosum (SCC) with a good prognosis. We describe two cases of MERS in two UK teaching hospitals.

Methods Case note review.

Results Case 1, a 13 year old African-Caribbean boy and Case 2, an 11 year old Caucasian girl with a diagnosis of ulcerative colitis treated with mercaptopurine [0.75 ml once daily (OD)] and mesalazine (1500 mg OD) presented with encephalopathy, headache, ataxia, and pseudobulbar features. Case 1 was febrile. Case 2 had an afebrile prodrome with sore throat, vomiting and diarrhoea (5 days). Both were treated with aciclovir and cefotaxime. Case 1 received clarithromycin. Both had an LP: the only abnormality being 10 white cells in the cerebrospinal fluid of case 1. Viral PCRs were negative. The MRI for case 1 revealed abnormal signal on T2/FLAIR and diffusion weighted imaging in the SCC with no gadolinium enhancement. Case 2 had similar findings and abnormal signal on T2/FLAIR in the cerebellar hemispheres. Both received a course of intravenous methylprednisolone, 1g OD, for 3 and 5 days respectively. Case 1 had evidence of a recent Mycoplasma pneumoniae infection (serum IgM antibody titre 1/640). He made a full recovery and MRI imaging findings resolved (2 week admission). Case 2 still had left upper limb dyspraxia and mild cognitive problems 5 weeks after onset of symptoms.

Conclusion Approximately 200 MERS cases have been reported since 2004 in association with bacterial, fungal, and viral illnesses – particularly influenza.The pathogenesis remains unclear, but inflammatory cytokine-mediated intramyelinic oedema has been suggested as a putative mechanism. The majority of cases make a full recovery within one week and all within one month. These two cases add to the number of cases of MERS reported outside of East Asia,and highlight MERS as a differential for para or post-infectious encephalopathy. Our case with an incomplete recovery also adds to the phenotype and if additional imaging changes are present, the prognosis may need to be more guarded.

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