Prognostic Value of Generalized Polyspike Trains and Prolonged Epileptiform EEG Runs.

INTRODUCTION: A considerable proportion of patients with genetic/idiopathic generalized epilepsy (IGE) suffer from persistent seizures. In this study, it was questioned if generalized polyspike trains (GPT) or prolonged epileptiform EEG runs allow identification of difficult-to-treat patients in a first seizure clinic setting or after recurrent seizures. METHODS: The first routine outpatient EEGs from untreated patients (later diagnosed with IGE) and routine EEGs from IGE patients with persistent seizures despite medical treatment were analyzed. Seizure outcome and clinical characteristics were retrospectively assessed based on the patients' records. RESULTS: In routine EEGs recorded after first seizure in untreated patients (n = 79), the prevalence of GPT (n = 1; 1.3%) and prolonged epileptiform EEG runs (n = 13; 16.5%) was low. At follow-up, 24 patients (30.4%) were not seizure free, and 3 (3.8%) of them developed drug-resistant IGE. None of the interictal discharges studied was associated with long-term seizure outcome. Treated IGE patients with recurrent seizures (n = 69) had a similar prevalence of GPT (n = 3; 4.3%) and prolonged epileptiform EEG runs (n = 7; 10.1%). At follow-up, 42 patients (60.8%) suffered persistent seizures, and 18 (26%) were drug resistant. Generalized polyspike train and prolonged epileptiform EEG runs had a higher prevalence in patients with drug-resistant epilepsy (GPT: 11.1% vs. 2%; P = 0.1; prolonged epileptiform EEG runs: 27.8% vs. 3.9%; P = 0.004) and persistent seizures (GPT: 7.1% vs. 0%; P = 0.16; prolonged epileptiform EEG runs: 16.7% vs. 0%; P = 0.03) as compared with nonresistant patients. CONCLUSIONS: Generalized polyspike train and prolonged epileptiform EEG runs were associated with persistent seizures and drug-resistant IGE, but the overall prevalence was low. In a first seizure clinic setting, the diagnostic value of these biomarkers was limited.

Transient epileptic amnesia diagnosed using long-term electroencephalography.

Transient epileptic amnesia (TEA) is a distinct syndrome affecting middle-aged persons without concurrent brain disease or disposition to epileptic seizures. Seizures are characterized by amnesia, usually lasting less than one hour, and interictal memory deficits that are common. Effective antiseizure treatment is usually rapid in patients with TEA, which underlines the need for prompt diagnosis. Here, we report a 58-year-old male patient with recurrent episodes of antero- and retrograde amnesia. MRI was normal and diagnosis was made using long-term EEG (27 hours), revealing 10 right-sided temporal lobe seizures with subtle clinical symptoms lasting up to 86 seconds. Details of the video-EEG are presented. Treatment with levetiracetam resulted in complete recovery and seizure freedom that was confirmed on a second long-term EEG. Given the favourable outcome with antiseizure treatment, our case study illustrates the role of long-term EEG monitoring in patients with recurrent transient amnesia to establish a correct diagnosis [Published with video sequence].