Objective: Our goal was to study the autoimmune mechanisms of neuroinflammation in progressive myoclonic ataxia.

Background: There are 2 different Ramsay Hunt syndromes named after this American neurologist: Ramsay Hunt syndrome type 1, also called cerebellar Ramsay Hunt syndrome, is a rare form of cerebellar degeneration that includes myoclonic ataxia with epilepsy, tremors and dementia. Ramsay Hunt syndrome type 2 is the reactivation of the herpes virus type 3 in the geniculate ganglion with the development of inflammation of the facial ganglion. Symptoms may include: damage to the lower motor neurons, facial and auditory nerves, dizziness, headaches, hearing loss. The disease is characterized by a triad: ear pain and vesicular rash around and inside the ear canal, ipsilateral facial palsy.

Method: Under our supervision there were 12 patients with type 1 Ramsay Hunt syndrome and 7 patients with type 2. Patients with type 2 syndrome were characterized by periodically occurring myoclonus during an epileptic seizure. Libraries of synthetic peptides designed to bind to HLA-DR3, which predisposes to both diseases, were examined using clonal CD4+ T cells reactive with glutamic acid decarboxylase 65-kilodalton isoform GAD65 isolated from patients with both types of Ramsay Hunt syndrome, and antibodies were determined ( GAD65) and antibodies to the herpes simplex virus by enzyme immunoassay.

Results: It was found that patients with type 1 Ramsay Hunt syndrome had expression of the NUS1 gene. Anti GAD65) antibody was detected in all 12 patients with type 1 syndrome and in 6 patients with type 2 syndrome. CD4+ T cells reactive with GAD65 were activated in all patients of both types. Antiviral anti-herpes antibodies were detected in 6 patients and 5 patients with type 2 syndrome. All type 2 syndrome patients demonstrated clear signs of myoclonic ataxia.

Conclusion: The presence of herpes viruses and antibodies to them has been proven in Ramsay Hunt Syndromes and types 1 and 2. It turned out that there is cross-reactivity between the herpes virus and GAD65. In other words, antibodies to this compound had the same effect and direction. Cross-reactivity of GAD65 and herpes virus antigens determines the diversity and partial similarity of symptoms in Ramsay Hunt syndrome types 1 and 2.

References: 1. Malco Rossi Sterre van der Veen 3 , Marcelo Merello , Marina A J Tijssen , Bart van de Warrenburg. Myoclonus-Ataxia Syndromes: A Diagnostic Approach.
Mov Disord Clin Pract/ 2020 Nov 3;8(1):9-24. doi: 10.1002/mdc3.13106.
2, Hoebert S. Hiemstra, Nanette C. Schloot, Peter A. van Veelen et al. Cytomegalovirus in autoimmunity: T cell crossreactivity to viral antigen and autoantigen glutamic acid decarboxylase. Proc Natl Acad Sci U S A. 2001 Mar 27; 98(7): 3988–3991.doi: 10.1073/pnas.071050898

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MDS Abstracts - https://www.mdsabstracts.org/abstract/progressive-myoclonic-ataxia-neuroinflammation-and-autoantibodies-against-inhibitory-synapses-and-herpes-viruses/