Monthly Case

In an otherwise healthy and appropriately developed 14-year-old boy, EEG recording revealed repetitive generalised 3 Hz spike-wave discharges of 3 to 4 s duration. It was unclear if this pattern was just interictal without clinical correlate or if it was an ictal seizure pattern indicating absences. Based on specifications given by the patients himself and his parents it remained elusive if the patient suffered from short episodes with loss of contact. However, this question is of high clinical relevance, as absence seizures require antiepileptic drug treatment while interictal activity does not.

During 24-h longterm-video-EEG recording the above mentioned EEG patterns occurred once to twice per hour. They were not associated with obvious alternations in behaviour. The patient was asked during the EEG discharges to press a pushbutton in response to a tone. He performed this task without any restrictions. We then asked the patient to read loudly from a book while constantly recording the EEG. With occurrence of 3 Hz spike-wave, the patient stumbled while reading, he was unable to continue. Even after the end of generalised discharges, he did not find the correct line on the page where he stopped reading a couple of seconds before.

Thus the reading test proved that the generalised EEG discharges have a clinical correlate characterised by a slight impairment of consciousness. This finding allowed to make the diagnosis of absence epilepsy, and antiepileptic treatment was started with ethosuximide. In a couple of weeks, we will repeat the reading test with EEG recording in order to assess the success of the initiated therapy.

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