Sign Up for a Free Account
  • Updated 07.06.2022
  • Released 07.07.2004
  • Expires For CME 07.06.2025

Epilepsy with auditory features

Introduction

Overview

In this article, the author reports on current extended knowledge on pathogenesis of RELN gene mutations, as well as understanding of thresholds of transsynaptic LGI1-ADAM22 protein complexes for disease symptomatology derived from recent animal studies. In addition, an update on drug-resistance presentation among families with lateral temporal lobe epilepsy, and response to surgical interventions is provided.

Key points

• Familial lateral temporal lobe epilepsy is typically characterized by auditory auras, but other types of clinical manifestations can be present in affected individuals.

• Approximately 50% of families have a genetic diagnosis clarified, of which mutations in the LGI1 gene or RELN gene are the most frequent. Other genes implicated with this syndrome include DEPDC5 and SCNA1 genes.

• Drug-resistant seizures and neuroimaging abnormalities might be present in some affected individuals, described in association with RELN mutations.

• Few cases in the literature report on surgical treatment of drug-resistant seizures, with good outcomes to date.

Historical note and terminology

Genetic factors in the causation of epilepsy have been recognized since the time of Hippocrates. However, until the second half of the 20th century, generalized epilepsies were thought to be genetic in origin, whereas focal epilepsies were largely attributed to environmental factors, such as birth injuries, infections, postnatal head trauma, and brain lesions such as tumors and vascular insults.

In a series of publications (05; 01; 02; 03) based on patients operated for focal epilepsy at the Montreal Neurological Hospital, Eva Andermann was able to demonstrate that genetic factors were important in patients with focal epilepsy, particularly temporal lobe epilepsy, and that both generalized and focal epilepsies fit a model of multifactorial inheritance (now termed complex inheritance), with interaction of 1 or more genes and environmental factors.

It was only in the 1990s that several autosomal dominant forms of focal epilepsy were described by the group of Berkovic and colleagues (12). These included: autosomal dominant nocturnal frontal lobe epilepsy, familial temporal lobe epilepsy, familial focal epilepsy with variable foci, and autosomal dominant rolandic epilepsy with speech dyspraxia.

Familial temporal lobe epilepsy was included in the proposals for classification of epileptic syndromes by the International League Against Epilepsy, supporting it as a well-defined syndrome (37; 36; 09).

The first description of familial lateral temporal lobe epilepsy was in 1995 by Ottman and colleagues, who reported an autosomal dominant focal epilepsy syndrome with auditory features (77). Thus, autosomal dominant partial epilepsy syndrome with auditory features was regarded as a familial form of temporal lobe epilepsy with seizures semiology pointing to a neocortical or lateral temporal generator.

After detailed descriptions of many families with temporal lobe epilepsy, it has been possible to define 2 groups of familial temporal lobe epilepsy based on clinical and molecular characteristics (96; 04): familial mesial temporal lobe epilepsy, with clinical features of mesial temporal onset and no clear-cut molecular definition to date (59; 56); and familial lateral temporal lobe epilepsy, first described in association with LGI1 gene mutations in chromosome 10q (77; 53; 75).

It is important to recognize that it is impossible to distinguish familial and nonfamilial temporal lobe epilepsy patients based solely on the clinical presentation, for both mesial and lateral forms. As the family history is not always accurately documented and because some family members are asymptomatic or only mildly affected, many so-called “sporadic” or “isolated” patients may actually have a familial epilepsy syndrome.

This is an article preview.
Start a Free Account
to access the full version.

  • Nearly 3,000 illustrations, including video clips of neurologic disorders.

  • Every article is reviewed by our esteemed Editorial Board for accuracy and currency.

  • Full spectrum of neurology in 1,200 comprehensive articles.

Questions or Comment?

MedLink®, LLC

3525 Del Mar Heights Rd, Ste 304
San Diego, CA 92130-2122

Toll Free (U.S. + Canada): 800-452-2400

US Number: +1-619-640-4660

Support: service@medlink.com

Editor: editor@medlink.com

ISSN: 2831-9125