Most common causes and mimics of encephalitis in immunocompetent adults in the UK
| Causes: |
| Viral: Herpes simplex virus types 1 and 2, varicella zoster virus, enteroviruses, adenovirus, parechovirus, measles virus, HIV |
| Autoimmune (main tumour associations in brackets): Antibodies against neuronal surface antigens: NMDAR antibody encephalitis (ovarian teratoma), LGI-1 antibody encephalitis (thymoma), antibodies against intracellular antigens: anti-Hu (small cell lung tumour), anti-Ma (testicular tumours), anti-GAD, acute disseminated encephalomyelitis, Bickerstaff's encephalitis |
| Mimics: |
| Infective: Systemic sepsis with encephalopathy, bacterial meningitis, TB, opportunistic infections in immunocompromised patients (eg crytococcus, toxoplasma, cytomegalovirus) |
| Inflammatory: Vasculitis, systemic lupus erythematosus with CNS involvement, Behçet's disease, neurosarcoidosis |
| Metabolic: Hypoglycaemia, hyponatraemia, hepatic encephalopathy, toxins (drugs, alcohol) |
| Neoplastic: Primary brain tumour (particularly low grade glioma mimicking CNS inflammation), metastases |
| Others: Status epilepticus from other causes, haemorrhagic or ischaemic stroke, psychiatric disease |
CNS = central nervous system; GAD = glutamic acid decarboxylase; LGI-1 = leucin-rich glioma inactivated 1; NMDAR = N-methyl D-aspartate receptor; TB = tuberculosis