Limbic Encephalitis
Overview
- Divides into paraneoplastic and nonparaneoplastic forms of limbic encephalitis.
- Paraneoplastic is typically secondary to anti-Hu (ANNA-1) intracellular autoantibodies from small cell lung cancer.
- Both present with limbic inflammation (medial temporal lobe T2-weighted MRI hyperintensity.
- Clinical manifestations fit with limbic lobe involvement:
- Neurobehavioral changes
- Sleep disturbances
- Delirium with/without hallucinations
- Memory loss, in particular short-term memory consolidation impairment with anterograde amnesia (think: Papez circuit).
- Seizures
Diagnostic Testing
- MRI typically manifests with T2-weighted/FLAIR hyperintensity in the medial temporal lobes.
- EEG may show focal or generalized slow and/or temporal lobe epileptic discharges/seizures.
- CSF may show a lymphocytic pleocytosis with elevated protein.
Paraneoplastic Causes
- Typically, intracellular autoantibodies but also neuronal cell-surface antibodies
Small cell lung cancer
Intraceullar antibodies:* anti-Hu (ANNA-1), anti-CV2/CRMP-5
Neuronal cell-surface antibodies:* anti-AMPA, anti-VGKC, anti-GABA-B
Thymoma
Intraceullar antibodies:* anti-CV2/CRMP-5
Neuronal cell-surface antibodies:* anti-AMPA, anti-VGKC
Testicular germ cell tumors
Intraceullar antibodies:* anti-Ma2 (Ta) antibodies
Ovarian Teratoma
Neuronal cell-surface antibodies:* anti-NMDA
Breast cancer
Neuronal cell-surface antibodies:* anti-AMPA
Treatment
- Treat the primary malignancy
- Ancillary treatments:
- Plasmapharesis
- IVIG
- Steroids