The Center for Functional Restoration

The Hyman-Newman Institute for Neurology and Neurosurgery
Beth Israel Medical Center, Singer Division
New York, NY

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Epilepsy

Introduction
Types of Epilepsy
Surgical Candidates
Surgical Evaluation
Surgery
Conclusion
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Types of Epilepsy
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Vagal Nerve Stimulator
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Landau-Kleffner Snydrome
Acquired Epileptiform Aphasia

Acquired epiletiform aphasia (AEA) or the Landau-Kleffner Syndrome is the lost of language associated with an abnormal Electroencephalogram (EEG). Typically, the onset of this type of language difficulty occurs between the third and seventh years of life in a child who had been developing normally. The EEG abnormalities (paroxysms) include bilateral spikes in the temporal or temporal and parietal lobes of the brain (at some point in the illness, all will exhibit this, especially during slow sleep); bilateral slow waves which are maximal over the temporal lobes; unifocal, multifocal or generalized spikes or spikes and slow waves; and continuous slow waves during slow sleep.

There are usually associated behavioral abnormalities which range from mild to severe. They include aggressiveness, hyperactivity, attention disorder, depression and rarely pyschosis.

The aphasia (loss of speech) first manefests itself as a word deafness with the child's parent experincing an increasing difficulty in having their child respond to them, even when they raise their voice. This progresses until there is a complete inability of the child to understand the speech of others. The child's speech then can deteriorate with speech becoming telegraphic. There is a decrease in vocabulary and an increasing use of jargon unrecognizable by others. These difficulties can fluctuate in severity and the severity will vary from child to child. Over time, speech improves to a varying degree. While this is the classically described course of language involvement, more recent papers have expanded the picture to include children who experience onset of the syndrome at a younger age and, hence, have poorly developed speech. Others have described children with this syndrome whose language skills do not improve but rather undergoes progressive deterioation.

As stated above, there are many forms of EEG abnormalities seen with this disorder. Associated clinical seizures are rare. They often occur at night and involve focal motor movements (such as shaking of an arm or leg, twitching of the corner of the mouth). They commonly resemble the pattern of seizures seen with benign partial epilepsy of childhood (a minor seizure disorder involving the region of the brain controlling movement of the arms and legs). As with benign partial epilepsy of childhood (BCECS), the seizures of AEA disappear after a few years. The earlier the onset of seizures and deterioration in language, the more severe the lingering deficit in language with the worst cases resembling an acquired deafness.

One of the greatest questions about this disorder is why there is such an apparent lack of correlation between language dysfunction and the degree of EEG abnormality. Worstening or improving language function typically cannot be documented by observed changes in the amount of abnormal EEG activity. There are documented cases of a failure in clinical improvement in children whose EEGs were normalized using medications. Consequently, some have questioned whether the recorded EEG abnormalities were responsible for the language deterioration or if they simply represented additional changes fostered by an underlying process which simply wasn't understood.

What is understood is brain tissue adjacent to a site where a seizure occurred will go through a period of impaired activity after expereincing a seizure. An example of this is the weakness or frank paralysis seen after a seizure which starts in or near the part of the brain involved in intiating movement. This weakness increases in degree and duration when the seizure lasts for a longer period or when there are a series of seizures. This is especially the case when the time between the seizures decreases. The function of the motor part of the brain is much less complex and there is more redundancy in brain tissue to perform this task than is the case with the regions of the brain involved in language. Consequently, it would not be surprising to see that the language centers of the brain in a young child would be particularily sensitive to seizure activity, especially if it were to occur during periods critical to language development.

A day time, random EEG may not be adequate to appreciate if abnormal activity is present and occasion abnormal activity may be sufficient to cause dysfunction in such a region involved in higher cognitive function. Dr. T.W. Deonna makes a compelling arguement that one can see progressive loss of higher cognitive function due to subclinincal epilepsy. With these type of seizures the main manefestation is an EEG abnormality which is seen most commonly at night.

Benign partial epilepsy of childhood, AEA and continuous spike-waves during slow sleep (CSWS) are three enities with identical EEG paroxysms recorded from different regions of the brain. The seizures seen with these disorders are self-limited, resolving with a few years of their onset. In BCECS there have been reported cases of focal motor seizures involving the muscles of the mouth, tongue and throat which translated into difficulties in speech, swallowing and drooling. As with AEA, these children can go through periods of increased seizure activity which are not responsive to medications. CSWS is associated with deterioartion or halting in the development of higher cognitive functions resulting in learning difficulties, behavioral disorders and intellectual development arrest. Deonna views these three entities as part of a continum and feels that it is the abnormal electrical activity occurring within developing regions of the brain critical for higher cognitive function which are responsible for the children's deterioration. In support, documented cases of improvemnt in cognitive function when the EEG abnormalities where successful treated for extended periods with antiepileptic drugs, corticosteriods or surgery are cited.

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