INDIVIDUAL TEST 875

NMDA receptor antibodies

IndicationSuspicion of anti-NMDA receptor encephalitis or for differential diagnosis of autoimmune encephalitis. Epileptic seizures may be an early symptom.MethodIndirect immunofluorescence using transfected cells.ResponseThe result is reported as positive or negative. A positive result is followed by a titer (serum).InterpretationAntibodies against the NMDAR (NR1 unit) are indicative of autoimmune encephalitis. NMDAR belongs to the family of ionotropic glutamate receptors and is widely expressed in the temporal lobe (limbic system). Signaling initiated by glutamate binding to the NMDA receptor is important for synaptic plasticity and cognitive functions such as memory and learning. Subacute personality change with cognitive effects, hallucinations, epileptic seizures, bizarre behavior, impaired memory and impaired orientation are examples of symptoms that indicate suspicion of autoimmune encephalitis if infectious cause can be excluded. Autoimmune encephalitis may be associated with malignancy.

NMDAR encephalitis often affects young women but may occur at all ages and in both sexes. NMDAR antibodies can be associated with ovarian teratoma (or testis teratoma for men), reported frequency varies between 9-56%. Early diagnosis and treatment is important, before permanent tissue damage occurs. Antibody titers can be used to monitor treatment effectiveness.

Generally, treatment with immunotherapy is more effective at autoantibodies directed against extracellular antigens than autoantibodies against intracellular antigens. In case of late diagnosis, permanent damage may occur when autoantibodies are considered pathogenic. Long treatment for several months to years duration may be required as well as follow up with cancer diagnosis.

Referenser: Lancaster, Martinez-Hernandez, Dalmau. Encephalitis and antibodies to synaptic and neuronal cell surface proteins. Neurology. 2011 Jul 12;77(2):179-89.  PMID: 21747075.

Titulaera et al. Screening for tumours in paraneoplastic syndromes: report of an EFNS Task Force. European Journal of Neurology. Epublished 2010. Eur J Neurol. 2011 January; 18(1): 19–23. PMID: 20880069.

Zuliani, Graus, Giometto, Bien, Vincent. Central nervous system neuronal surface antibody associated syndromes: review and guidelines for recognition. J Neurol Neurosurg Psychiatry 2012;83:638-645. PMID: 22448032.

Dalmau, Tuzan, Wu et. al. Paraneoplastic anti- N-metyl-D-aspartat receptor encephalitis associated with ovarian teratoma. Ann Neurol 2007;61:25-36. PMID 17262855.

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Neurology

ENSKILD ANALYS 875

NMDA receptor-antikroppar

IndikationMisstanke om anti-NMDA receptor encefalit eller vid differentialdiagnostik av autoimmun encefalit. Epileptiska kramper kan vara ett tidigt symtom.MetodIndirekt immunofluorescens med transfekterade celler.SvarResultatet anges som positiv eller negativ. Positivt resultat titreras (serum).TolkningAntikroppar mot NMDAR (NR1-enheten) talar för autoimmun encefalit. NMDAR hör till familjen av jonotropa glutamatreceptorer och uttrycks rikligt i temporalloben (limbiska systemet). Signalering som initieras av att glutamat binder till NMDA-receptorn är viktiga för synaptisk plasticitet och kognitiva funktioner som minne och inlärning. Subakut personlighetsförändring med kognitiv påverkan, hallucinationer, epileptiska anfall, bisarrt beteende, nedsatt minne och försämrad orienteringsförmåga är exempel på symtom som inger misstanke om autoimmun encefalit om infektiös orsak kan uteslutas. Autoimmun encefalit kan vara kopplad till malignitet.

NMDAR-encefalit drabbar ofta unga kvinnor, men kan förekomma i alla åldrar och även hos män. NMDAR antikroppar kan vara förknippade med ovarie teratom (eller testis teratom för män), rapporterad frekvens varierar mellan 9-56%. Tidig diagnos och behandling innan permanent vävnadsskada har skett är viktigt. Antikroppstitrar kan användas för att följa behandlingseffektivitet.

Generellt sett är behandling med immunoterapi oftare effektfull vid autoantikroppar riktade mot extracellulära antigen än vid autoantikroppar mot intracellulära antigen. Vid sen diagnos kan permanenta skador har skett då autoantikropparna anses vara patogena. Lång behandling i flera månader till års varighet kan krävas samt uppföljning med cancerdiagnostik.

ReferenserLancaster, Martinez-Hernandez, Dalmau. Encephalitis and antibodies to synaptic and neuronal cell surface proteins. Neurology. 2011 Jul 12;77(2):179-89.  PMID: 21747075

Titulaera et al. Screening for tumours in paraneoplastic syndromes: report of an EFNS Task Force. European Journal of Neurology. Epublished 2010. Eur J Neurol. 2011 January; 18(1): 19–23. PMID: 20880069.

Zuliani, Graus, Giometto, Bien, Vincent. Central nervous system neuronal surface antibody associated syndromes: review and guidelines for recognition. J Neurol Neurosurg Psychiatry 2012;83:638-645. PMID: 22448032

Dalmau, Tuzan, Wu et. al. Paraneoplastic anti- N-metyl-D-aspartat receptor encephalitis associated with ovarian teratoma. Ann Neurol 2007;61:25-36. PMID 17262855.

 

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