Antibodies that Cause Epilepsy

In the March 6 early view online version of Epilepsia, Doctors Brenner and colleagues from the United Kingdom present an analysis of linking epilepsy to specific antibody syndromes. The purpose of the study was to address how frequently certain individuals with epilepsy present with specific antibody-related syndromes. This is particularly troublesome because in many cases these individuals do not respond to medication. The investigators screened two large epilepsy groups to investigate the prevalence of antibodies in adult patients with either established or newly diagnosed untreated epilepsy.

The investigators found that 11% of the patients had antibodies to one or more antigens:

• Voltage-gated potassium channel
• Complex protein
• Glycine receptors
• Glutamic acid decarboxylase (GAD)
• NMDA receptors

There was no difference in the prevalence of antibodies individually or collectively between patients with established and newly diagnosed epilepsy or with generalized or focal epilepsy. There was, however, a higher prevalence of positive antibody titers in patients with focal epilepsy of unknown cause than in those with structural metabolic focal epilepsy. Newly diagnosed antibody positive patients were less likely to achieve adequate seizure control with the needed initial treatment than antibody negative patients but this was a trend and not a statistical finding. The investigators concluded that the presence of autoantibodies is equally common in newly diagnosed and in established epilepsy and therefore not likely to be a side effect of having longstanding epilepsy but rather perhaps the cause of the seizures themselves.

Why is this important?

This study is a further reminder that at least in 10% of patients who present with epilepsy has from an immune-based condition. More work is needed in order to understand how to better screen and identify these individuals, because the treatment of epilepsy may be different than how other seizure patients are managed with seizure drugs. Immune-based medications may need to be considered.