Table 1 Clinical features of anti-synaptic and anti-glutamic acid decarboxylase autoimmune encephalitides
Clinical features | NMDAR, (NR1 subunit) | VGKC-complex (Kv1 subunit, LGI1, CASPR2) | AMPAR (GluR1, GluR2 subunits) | GABABR (B1 subunit) | GAD (65 kDa) |
|---|---|---|---|---|---|
Age (years) | 18 to 50 | Less than 50 | Less than 50 | 60 to 70 | Less than 50 |
Sex (% female) | 75% | 66% | Greater than 50% | 50% | Less than 50% |
Etiology | Â | Â | Â | Â | Â |
  Paraneoplastic (%, and commonly occurring cancers) | 9% to 56% have ovarian teratoma, predominately females less than 18 years of age | 10% to 30%; low titers; SCLC; thymoma; CASPR2>>LGI-1 | 50% to 70%; SCLC, breast carcinoma; thymoma | 50%; SCLC thymoma | Rarely associated with cancer |
  Nonparaneoplastic | Approximately 50% | 70%; high titers | 30% to 50% | 50% | Frequent |
Anatomical subtype | Â | Â | Â | Â | Â |
  Limbic encephalitis | Less common | Typical | Typical | Typical | Typical |
  Panencephalitis | Typical | Rare (involving basal ganglia) | Unclear | Unclear | Less common |
CSF abnormal (%) | 90% | 40% | 90% | 80% | 20% |
Psychiatric Features | Common and pronounced: Anxiety, agitation, paranoid delusions, perceptual changes, erratic behavior, speech changes, severe psychosis | Agitation, anxiety, panic-attacks, depression, psychosis, hallucinations, delusions, delirium, confabulation | Atypical psychosis, which can be isolated | Paranoia, behavioral changes | Depression, atypical psychosis (case reports) |
Neurological Features | Early features: seizures, cognitive/memory impairment; Late features: catatonia, orofacial and limb dyskinesia, dystonia, autonomic dysfunction, reduced level of consciousness, aphasia, central hypoventilation | LGI1: limbic encephalitis (more common): amnesia temporal lobe seizures, tonic seizures, and hypernatremia. Extrapyramidal symptoms (choreoathetosis) and extra-temporal (faciobrachial dystonic) seizures (less common). CASPR2: limbic encephalitis, Morvan's syndrome (neuromyotonia, REM disorder, insomnia, and autonomic dysfunction). | Memory impairment, temporal lobe seizures | Prominent temporal lobe seizures, memory impairment, concomitant glutamic acid decarboxylase autoantibodies | Stiff-person syndrome, cerebellar ataxia, cognitive/memory impairment, epilepsy (often mesial temporal) |
Response to treatment | Highly responsive to immune therapy and removal of ovarian teratoma | Highly responsive to immune therapy | Moderately responsive to immune therapy | Moderately responsive to immune therapy | Often refractory to immune therapy |
Relapse risk | 20% often with psychiatric signs; may indicate tumor reoccurrence | Rarely relapses | Tendency to relapse (based on small case series) | Tendency to relapse (based on small case series) | Tendency to be chronic and relapse |