Autoimmune Epilepsy

What is autoimmune epilepsy?

Autoimmune epilepsy is a group of epilepsies mediated by all kinds of autoimmune reactions (Jang et. al., 2020). There are a number of autoimmune conditions that lead to the individual having seizure activity. Autoimmune epilepsy also includes febrile illness-related refractory seizures (FIRES), new-onset refractory status epilepticus (NORSE), cerebral autoinflammatory diseases, and epilepsy induced by systemic autoimmune disorders (Jang et. al., 2020).

What causes autoimmune epilepsy?

Many of the cases of autoimmune epilepsy involve autoimmune limbic encephalitis. Autoimmune limbic encephalitis is defined as an inflammatory disease involving the medial temporal lobes, resulting in short-term memory deficits, seizures, or psychiatric symptoms (Budhram et. al, 2019).

Diagnosis

Diagnosis for autoimmune limbic encephalitis was first presented in the article, A clinical approach to diagnosis of autoimmune encephalitis, published in 2016 by Francesc Graus and colleagues of his. The diagnosis criteria, known as the Graus criteria consists of the following:

·????????Subacute onset (rapid progression of less than 3 months) of working memory deficits, seizures, or psychiatric symptoms suggesting involvement of the limbic system.

·????????Bilateral brain abnormalities on T2 – weighted fluid-attenuated inversion recovery MRI highly restricted to the medial temporal lobes.

At least one of the following must also take place:

·????????Cerebrospinal Fluid pleocytosis (white blood cell count of more than 5 cells per mm3)

·????????EEG with epileptic or slow-wave activity involving the temporal lobes

·????????Reasonable exclusion of alternative causes

(Budhram et. al., 2019)

Tests that are conducted to diagnose autoimmune epilepsy include cerebrospinal fluid analysis, neuroimaging, electroencephalogram, autoantibody tests, and brain biopsy.

Signs and symptoms

There are many situations that can cause autoimmune epilepsy. Prodromal or early symptoms can be:

·????????Fever

·????????Headache

·????????Dizziness

·????????Insomnia

·????????Upper respiratory infection

(Jang et. al., 2020)

Symptoms that are caused by autoimmune limbic encephalitis include altered mental status, psychiatric symptoms, or memory deficits (Jang et. al., 2020). Depending on the type of encephalitis is diagnosed, additional symptoms can include psychosis, dyskinesia, hypoventilation, autonomic dysfunction, seizures, refractory status epilepticus, and memory decline.

Tumors can cause symptoms of autoimmune epilepsy. Examples include ovarian tumors, thymoma, small-cell lung cancer, and neuroendocrine tumors (Jang et. al., 2020). A spinal tap can help in detecting any bacteria that can mimic autoimmune epilepsy such as listeria, tuberculosis, or borrelia (Jang et. al., 2020). Magnetic resonance imaging (MRI) can detect hyperintensities in the medial temporal lobes or multifocal brain lesions (Jang et. al., 2020). Electroencephalograms (EEG) can help to detect seizure activity. Autoantibody tests can provide a diagnosis of autoimmune encephalitis and is recommended for any patient that is suspected of having it (Jang et. al., 2020). For patients who are not responding to empirical immunotherapy (treatment option), a brain biopsy may be done. The purpose of the biopsy is to exclude other conditions such as lymphoma, primary angiitis of the central nervous system, demyelinating disease, or other malignancies (Jan et. al., 2020).

Treatment options

Autoimmune epilepsy is treated by immunotherapy, removal of an immunologic trigger such as a tumor (when one is present) and anti-epileptic medications (Husari and Dubey, 2019). Immunotherapy is divided into two treatment cycles, the acute phase, then the maintenance phase. Depending on the severity of the case will decide on how aggressive of action needs to be taken with treatment.

Anticonvulsant medications help with the maintenance phase to prevent seizure activity. In the article, Autoimmune Epilepsy, the authors pointed out that sodium channel blockers such as carbamazepine, phenytoin, oxcarbazepine, and lacosamide had the best success in controlling seizure activity.

Surgery has been tried in some cases of autoimmune epilepsy, but studies show that the outcomes seem to be worse compared to other forms of drug-resistant epilepsy (Husari and Dubey, 2019).

Conclusion

Autoimmune epilepsy is a group of epilepsies mediated by all kinds of autoimmune reactions. Many cases of autoimmune epilepsy involve autoimmune limbic encephalitis. The Graus criteria is used to make a diagnosis when it comes to autoimmune encephalitis. Different signs and symptoms can take place depending on the cause. Treatment options include immunotherapy, antiepileptic medication, and surgery.

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Resources:

Budhram, A., Leung, A., Nicolle, M. W., & Burneo, J. G. (2019). Diagnosing autoimmune limbic encephalitis. CMAJ : Canadian Medical Association journal = journal de l'Association medicale canadienne, 191(19), E529–E534. https://doi.org/10.1503/cmaj.181548

Graus, F., Titulaer, M. J., Balu, R., Benseler, S., Bien, C. G., Cellucci, T., Cortese, I., Dale, R. C., Gelfand, J. M., Geschwind, M., Glaser, C. A., Honnorat, J., H?ftberger, R., Iizuka, T., Irani, S. R., Lancaster, E., Leypoldt, F., Prüss, H., Rae-Grant, A., Reindl, M., … Dalmau, J. (2016). A clinical approach to diagnosis of autoimmune encephalitis. The Lancet. Neurology, 15(4), 391–404. https://doi.org/10.1016/S1474-4422(15)00401-9

Husari, K. S., & Dubey, D. (2019). Autoimmune Epilepsy. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics, 16(3), 685–702. https://doi.org/10.1007/s13311-019-00750-3

Jang, Y., Kim, D. W., Yang, K. I., Byun, J. I., Seo, J. G., No, Y. J., Kang, K. W., Kim, D., Kim, K. T., Cho, Y. W., Lee, S. T., & Drug Committee of Korean Epilepsy Society (2020). Clinical Approach to Autoimmune Epilepsy. Journal of clinical neurology (Seoul, Korea), 16(4), 519–529. https://doi.org/10.3988/jcn.2020.16.4.519 ?????