Neurology Practice Changers 2014

Bret S. Stetka, MD; Andrew N. Wilner, MD

Disclosures

December 08, 2014

In This Article

Epilepsy

The standard definition of epilepsy requires two unprovoked seizures at least 24 hours apart. This year, the International League Against Epilepsy (ILAE) updated the definition of epilepsy to better accommodate common clinical circumstances, such as people who have had only one seizure but who have a high likelihood of a second seizure; people with epilepsy syndromes; those with reflex epilepsy; and those who have had prolonged seizure-free periods.[28]

The new ILAE practical definition of epilepsy may be applied to any of the following conditions:

At least two unprovoked (or reflex) seizures occurring > 24 hours apart;

One unprovoked (or reflex seizure) and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years; and

Diagnosis of an epilepsy syndrome.

In addition, epilepsy is considered to be "resolved" for individuals who had an age-dependent epilepsy syndrome but are now past the applicable age or those who have remained seizure-free for the past 10 years, with no seizure medicines for the past 5 years.

The definition of epilepsy has traditionally excluded "provoked seizures," but the new definition includes persons with photosensitive seizures who had previously been semantically excluded from having the diagnosis of epilepsy. In addition, patients who have had a single seizure, but with an underlying lesion such as stroke that is likely to produce further seizures, may receive the diagnosis of epilepsy. And for patients with a single seizure and clinical history and EEG suggestive of an epilepsy syndrome, a second seizure is no longer required to make the diagnosis of epilepsy.

The new definition also allows those patients who have "outgrown" their seizures owing to an age-dependent condition, such as benign rolandic epilepsy, and those who have been seizure-free for 10 years without medications for the past 5 years to unburden themselves of an epilepsy diagnosis. Consequently, epilepsy need no longer be considered a lifelong diagnosis in every patient.

Partial complex and convulsive seizures are characterized by an alteration of consciousness. Despite years of investigation, how the brain maintains consciousness and how seizures disrupt it have not been well elucidated. During a recent depth electrode study of a 54-year-old woman with intractable epilepsy, direct stimulation of the left anterior-dorsal insula/claustrum region resulted in "immediate impairment of consciousness, in 10 out of 10 times, with arrest of reading, onset of blank staring, unresponsiveness to auditory or visual commands, and slowing of spontaneous respiratory movements."[29] There was no electrical after discharge, suggesting that the anterior insula, claustrum, or both, form part of a network that is fundamentally important to the conscious state.

This is the first depth electrode study to induce loss of consciousness by stimulation of a specific brain location. It is unclear whether this finding may be generalized to other people with epilepsy or people without epilepsy. This observation may lead to a greater understanding of the pathophysiology of alteration of consciousness during epileptic seizures, as well as the functional organization of the human brain.

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