The timely implementation of
immunotherapy is key to successful treatment of autoimmune
encephalopathies or
dementias (from here on will be referred to as autoimmune
encephalopathies). There are different levels of diagnostic certainty which should guide the immunological treatment of autoimmune
encephalopathies. There is a high level of diagnostic certainty for patients who have classic
limbic encephalitis and have a neural antibody detected in serum or CSF (such as
potassium channel complex antibody). For these patients, initiating high-dose
corticosteroids or
IVIg is indicated, with
plasma exchange,
rituximab or
cyclophosphamide used as second-line
therapy if first-line
therapy proves only partially beneficial. There is a lower level of diagnostic certainty in patients with non-limbic atypical phenotypes (though rapidly progressive) when no neural antibody is detected in serum and CSF. A trial of
corticosteroids or
IVIg (or both sequentially) may be undertaken in these patients, but if no objective improvements occur, further
immunotherapy is unlikely to be beneficial.
Antiepileptic treatment also plays a critical role in those who have
seizures as well as
cognitive symptoms. Evaluation for and treatment of any underlying
cancer is another component for those patients with a paraneoplastic cause of
encephalitis. An individualized maintenance regimen needs to be designed for patients who do improve with
immunotherapy. Individual factors that need to be considered when formulating a program of maintenance treatment include disease severity, antibody specificity and proclivity for disease relapse.
Azathioprine and
mycophenolate mofetil are frequently used for the purpose of remission maintenance, and should permit gradual withdrawal of
steroids,
IVIg or more toxic
immunosuppressants. The duration of maintenance
therapy is uncertain, but this author typically recommends 3-5 years of relapse-free maintenance treatment before discontinuing
immunotherapy altogether.