Prevalence
Small; 1 to 2 cases annually in specialized centers.

Age at onset
Mainly before the age of 6 years; peak at 3 to 6 years.

Sex
Twice as many males as females.

Neurological and mental state
Normal prior to seizure onset.

Etiology
Childhood dysfunctional disorder probably as the result of an epileptogenic ‘functional lesion’ in the speech cortex during a critical period of child development. Symptomatic cases are rare.

Clinical manifestations
Linguistic abnormalities (100%) and seizures (75%). It starts with verbal auditory agnosia (inability to respond to linguistic and later non-linguistic sounds). Progress is subacute or step-wise (stuttering and fluctuating). All types of aphasia may appear. Finally, the child may become entirely mute, failing to respond to even non-verbal sounds. Remissions and exacerbations are common.

Cognitive and behavioral problems occur in more than 3/4 of patients.

Infrequent seizures (generalized tonic-clonic seizures, focal motor, atypical absences, and atonic seizures or a single or isolated status epilepticus) occur in 3/4 of patients.

Timing
Seizures often nocturnal.

Diagnostic procedures
MRI is often normal; functional brain imaging demonstrates abnormalities in the dominant temporal lobe.

Inter-ictal EEG
Posterior temporal sharp slow-wave foci that are often multifocal and bisynchronous. Continuous spikes and waves during slow sleep (CSWS) occur at some stage of the illness in nearly all cases, but this is not a prerequisite for diagnosis.

Ictal EEG
Seizure dependent.

Prognosis
Usually bad. Seizures and EEG abnormalities remit by the age of 15 years, and language and neuropsychological disturbances gradually improve. However, only 10% to 20% achieve complete normalization. All others are left with permanent and often severe sequelae. Outcome does not depend on frequency and type of seizure.

Differential diagnosis
Acquired deafness or elective mutism; epilepsy with continuous spikes and waves during slow-wave sleep (CSWS), benign or severe childhood focal epilepsies.

Management options*
Seizures are easily controlled with AEDs. The aim is to reduce the epileptiform EEG discharges.

Valproate, ethosuximide, clobazam#, and sulthiame# are used. Lamotrigine, levetiracetam, topiramate, and zonisamide may be tried. ACTH or prednisone is often the treatment of choice, particularly in new and younger patients. There is an empirical view that the results depend on early treatment with high initial doses of ACTH or steroids for at least 3 months. Continuation of treatment after this period depends on response and side effects. Steroids are usually used with valproate or benzodiazepines and these may remain after steroid wean. Subpial intracortical transections have relatively good success.

*Expert opinion, please check FDA-approved indications and prescribing information
#Not approved by the FDA

See also: http://professionals.epilepsy.com/page/syndromes_lanau.html

This page was adapted from:

The educational kit on epilepsies
The epileptic syndromes
By C. P. Panayiotopoulos

Originally published by MEDICINAE
21 Cave Street, Oxford OX4 1BA
First published 2006 and reprinted in 2007