Autoimmune Encephalitis causes
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Julinka Auta Fernandes
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Differentiating Autoimmune Encephalitis from Other Conditions |
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Autoimmune Encephalitis On the Web |
Overview
Autoimmune encephalitis results from an immune response directed against components of the central nervous system. Its etiological contexts include disease with no identified precipitating trigger, tumor-associated autoimmunity, postinfectious autoimmunity, and iatrogenic autoimmunity, particularly following immune checkpoint inhibitors.[1] A disease-relevant neuronal antibody may identify an immunological subtype without revealing its initiating trigger. Tumor associations vary between subtypes, and some patients meeting accepted diagnostic criteria have no detectable currently recognized neuronal antibody.[2]
Causes
Life-threatening causes
Autoimmune encephalitis can itself be life-threatening, irrespective of the precipitating trigger. Status epilepticus, severe autonomic instability, central hypoventilation, and a reduced level of consciousness may require emergency treatment and intensive care. These are complications of the encephalitis rather than separate etiological categories.[3]
Common causes
Autoimmune encephalitis has two major clinical contexts: nonparaneoplastic disease and tumor-associated disease. Their relative frequency depends on the antibody subtype and population; the following categories do not represent a universal frequency ranking.[2]
- Nonparaneoplastic autoimmunity without an identified trigger: This includes many leucine-rich glioma-inactivated 1 (LGI1)- and N-methyl-D-aspartate receptor (NMDAR)-associated cases. An unidentified trigger does not mean that neuronal antibody testing must be negative.[2]
- Tumor-associated autoimmunity: A neoplasm can initiate an immune response that cross-reacts with neural antigens. The neurological syndrome may precede discovery of the tumor. Paraneoplastic attribution requires assessment of the clinical phenotype, antibody, and tumor relationship; it is distinct from direct tumor invasion or metastasis.[4]
Characteristic tumor associations are summarized below. These are associations with particular immune syndromes; they do not mean that every patient with that antibody has a tumor.
| Associated tumor | Antibody-associated syndrome or relevant context |
|---|---|
| B-cell lymphoproliferative neoplasms | Rarely associated with dipeptidyl-peptidase-like protein 6 (DPPX)-antibody encephalitis; reported neoplasms include lymphoma and chronic lymphocytic leukemia.[5] |
| Breast carcinoma | Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-antibody encephalitis; amphiphysin-associated paraneoplastic syndromes may also occur.[6][3] |
| Hodgkin lymphoma | Metabotropic glutamate receptor 5 (mGluR5)-antibody encephalitis, historically associated with the term Ophelia syndrome.[7] |
| Ovarian teratoma | NMDAR-antibody encephalitis. The associated teratoma can be mature and benign; tumor-associated disease is not synonymous with malignant disease.[8] |
| Small-cell lung carcinoma | Gamma-aminobutyric acid type B receptor (GABABR) encephalitis; Hu (antineuronal nuclear antibody type 1; ANNA-1)- and collapsin response-mediator protein 5 (CRMP5)-associated paraneoplastic encephalitic or encephalomyelitic syndromes.[9][3] |
| Testicular germ-cell tumors | Ma2 (paraneoplastic antigen Ma2)-associated encephalitis and kelch-like protein 11 (KLHL11)-associated rhombencephalitis or related brainstem–cerebellar syndromes.[3] |
| Thymoma | Contactin-associated protein-like 2 (CASPR2)-associated disease, particularly with Morvan syndrome; AMPAR- and gamma-aminobutyric acid type A receptor (GABAAR) encephalitis are additional associations.[10][6][11] |
Less common causes
Autoimmune encephalitis also occurs in the following recognized contexts. Their frequency depends on the population being considered; post-herpes autoimmunity, for example, is an important complication within the subgroup recovering from herpes simplex encephalitis.
- Iatrogenic autoimmunity, particularly following immune checkpoint inhibitors: Cancer immunotherapy targeting programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), or cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) can be associated with immune-mediated encephalitis. This may represent a new immune syndrome or exacerbation of pre-existing disease. Attribution requires exclusion of competing causes, including infection, tumor involvement, and metabolic disturbances; exposure alone is insufficient.[12] Other immune-modulating agents are also recognized potential iatrogenic triggers.[1]
- Postinfectious autoimmunity after herpes simplex encephalitis: New or worsening neuropsychiatric symptoms, seizures, or movement disorders can reflect an autoimmune relapse following the initial infection. NMDAR antibodies and other neuronal antibodies may be involved. This process must be distinguished from persistent infection or viral reactivation.[13]
Active infectious encephalitis, toxic or metabolic encephalopathy, and primary psychiatric disorders are alternative diagnoses, rather than established causes of neuronal autoimmune encephalitis. A positive nonspecific antibody result alone does not establish an autoimmune etiology.[14]
Causes by organ system
Autoimmune encephalitis triggers and tumor associations can be mapped to the following systems. Categories overlap. A dash indicates that no separate established etiological entry is listed for that system; it does not exclude disorders of that system from the differential diagnosis.
| Organ system or category | Relevant trigger, association, or etiological context |
|---|---|
| Cardiovascular | — |
| Chemical/Poisoning | — |
| Dental | — |
| Dermatologic | — |
| Drug Side Effect | Immune checkpoint inhibitor-associated encephalitis.[12] |
| Ear Nose Throat | — |
| Endocrine | — |
| Environmental | — |
| Gastroenterologic | — |
| Genetic | Human leukocyte antigen (HLA) associations indicate susceptibility in some subtypes, including LGI1- and CASPR2-antibody disease; they do not establish a single-gene cause of autoimmune encephalitis.[15] |
| Hematologic | Hodgkin lymphoma; rare B-cell lymphoproliferative neoplasms.[7][5] |
| Iatrogenic | Immune checkpoint inhibitor-associated encephalitis.[12] |
| Infectious Disease | Autoimmune encephalitis following herpes simplex encephalitis, distinct from ongoing viral infection.[13] |
| Musculoskeletal/Orthopedic | — |
| Neurologic | Neural autoimmunity with no identified precipitating trigger.[1] |
| Nutritional/Metabolic | — |
| Obstetric/Gynecologic | Ovarian teratoma-associated NMDAR encephalitis.[8] |
| Oncologic | Tumor-associated autoimmunity; see the tumor association table above.[4] |
| Ophthalmologic | — |
| Overdose/Toxicity | — |
| Psychiatric | — |
| Pulmonary | Small-cell lung carcinoma-associated autoimmunity.[9][3] |
| Renal/Electrolyte | — |
| Rheumatology/Immunology/Allergy | Autoimmune inflammation of the central nervous system, with or without an identified trigger.[1] |
| Sexual | — |
| Trauma | — |
| Urologic | Testicular germ-cell tumor-associated autoimmunity.[3] |
| Miscellaneous | No identified precipitating trigger after appropriate evaluation.[1] |
Causes in alphabetical order
Autoimmune encephalitis etiological categories can be summarized alphabetically as follows:[1]
- Iatrogenic autoimmunity, including immune checkpoint inhibitor-associated disease.
- Nonparaneoplastic autoimmunity without an identified precipitating trigger.
- Postinfectious autoimmunity, particularly following herpes simplex encephalitis.
- Tumor-associated autoimmunity.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Abboud H, Probasco JC, Irani S, et al. (2021). "Autoimmune encephalitis: proposed best practice recommendations for diagnosis and acute management". J Neurol Neurosurg Psychiatry. 92 (7): 757–768. doi:10.1136/jnnp-2020-325300. PMID 33649022 Check
|pmid=value (help). - ↑ 2.0 2.1 2.2 Hahn C, Budhram A, Alikhani K, et al. (2024). "Canadian Consensus Guidelines for the Diagnosis and Treatment of Autoimmune Encephalitis in Adults". Can J Neurol Sci. 51 (6): 734–754. doi:10.1017/cjn.2024.16. PMID 38312020 Check
|pmid=value (help). - ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Michael BD, Huang Y, McKeever S, et al. (2026-10). "Management of suspected infectious and autoimmune encephalitis in adults – National Guidelines from the United Kingdom Joint Societies". J Infect: 106873. doi:10.1016/j.jinf.2026.106873. PMID 42863638 Check
|pmid=value (help). Check date values in:|date=(help) - ↑ 4.0 4.1 Graus F, Vogrig A, Muñiz-Castrillo S, et al. (2021). "Updated Diagnostic Criteria for Paraneoplastic Neurologic Syndromes". Neurol Neuroimmunol Neuroinflamm. 8 (4): e1014. doi:10.1212/NXI.0000000000001014. PMID 34006622 Check
|pmid=value (help). - ↑ 5.0 5.1 Hara M, Ariño H, Petit-Pedrol M, et al. (2017). "DPPX antibody-associated encephalitis: Main syndrome and antibody effects". Neurology. 88 (14): 1340–1348. doi:10.1212/WNL.0000000000003796. PMID 28258082.
- ↑ 6.0 6.1 Höftberger R, van Sonderen A, Leypoldt F, et al. (2015). "Encephalitis and AMPA receptor antibodies: Novel findings in a case series of 22 patients". Neurology. 84 (24): 2403–2412. doi:10.1212/WNL.0000000000001682. PMID 25979696.
- ↑ 7.0 7.1 Spatola M, Sabater L, Planagumà J, et al. (2018). "Encephalitis with mGluR5 antibodies: Symptoms and antibody effects". Neurology. 90 (22): e1964–e1972. doi:10.1212/WNL.0000000000005614. PMID 29703767.
- ↑ 8.0 8.1 Dalmau J, Tüzün E, Wu HY, et al. (2007). "Paraneoplastic anti-N-methyl-D-aspartate receptor encephalitis associated with ovarian teratoma". Ann Neurol. 61 (1): 25–36. doi:10.1002/ana.21050. PMID 17262855.
- ↑ 9.0 9.1 Lancaster E, Lai M, Peng X, et al. (2010). "Antibodies to the GABAB receptor in limbic encephalitis with seizures: case series and characterisation of the antigen". Lancet Neurol. 9 (1): 67–76. doi:10.1016/S1474-4422(09)70324-2. PMID 19962348.
- ↑ van Sonderen A, Ariño H, Petit-Pedrol M, et al. (2016). "The clinical spectrum of Caspr2 antibody-associated disease". Neurology. 87 (5): 521–528. doi:10.1212/WNL.0000000000002917. PMID 27371488.
- ↑ Spatola M, Petit-Pedrol M, Simabukuro MM, et al. (2017). "Investigations in GABAA receptor antibody-associated encephalitis". Neurology. 88 (11): 1012–1020. doi:10.1212/WNL.0000000000003713. PMID 28202703.
- ↑ 12.0 12.1 12.2 Guidon AC, Burton LB, Chwalisz BK, et al. (2021). "Consensus disease definitions for neurologic immune-related adverse events of immune checkpoint inhibitors". J Immunother Cancer. 9 (7): e002890. doi:10.1136/jitc-2021-002890. PMID 34281989 Check
|pmid=value (help). - ↑ 13.0 13.1 Armangue T, Spatola M, Vlagea A, et al. (2018). "Frequency, symptoms, risk factors, and outcomes of autoimmune encephalitis after herpes simplex encephalitis: a prospective observational study and retrospective analysis". Lancet Neurol. 17 (9): 760–772. doi:10.1016/S1474-4422(18)30244-8. PMID 30049614.
- ↑ Graus F, Titulaer MJ, Balu R, et al. (2016). "A clinical approach to diagnosis of autoimmune encephalitis". Lancet Neurol. 15 (4): 391–404. doi:10.1016/S1474-4422(15)00401-9. PMID 26906964.
- ↑ Binks S, Varley J, Lee W, et al. (2018). "Distinct HLA associations of LGI1 and CASPR2-antibody diseases". Brain. 141 (8): 2263–2271. doi:10.1093/brain/awy109. PMID 29788256.