The Diagnostic Significance of Sleep Electroencephalograms in Temporal Lobe Epilepsy

Niedermeyer, E.; Rocca, Uldarico

doi:10.1159/000114418

Cited by 77 publications

(26 citation statements)

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“…First, spiking rates in FoEs outnumbered those in scalp electrodes by a factor of 2 to 10. This aspect of surface-deep discrepancy is well known (20). The second discrepancy pertained to a difference between scalp and FoE spiking-rate distribution across different vigilance states.…”

Section: Figmentioning

confidence: 86%

Interictal Epileptic Spiking during Sleep and Wakefulness in Mesial Temporal Lobe Epilepsy: A Comparative Study of Scalp and Foramen Ovale Electrodes

et al. 2003

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Summary:Purpose: To assess distribution of temporal lobe spikes across different states of sleep and wakefulness in simultaneous scalp and foramen ovale (Fo) recordings.Methods: The study included 12 patients with mesial temporal lobe epilepsy (MTLE). As part of their presurgical evaluation, patients underwent long-term video-EEG monitoring with combined scalp and foramen ovale electrodes (FoEs). In addition to traditional sleep scoring, waking was subdivided into eyes-opened and eyes-closed states, and rapid-eyemovement (REM) sleep was divided into phasic and tonic states. Spike counts were carried out visually for scalp and FoEs, and spiking rates were determined for each state. A ratio between FoE and scalp spiking rates also was calculated for each state.Results: Scalp spiking showed a significant increase during NREM3,4, whereas FoE spiking increased during NREM2. The scalp/FoE ratio significantly increased during NREM3,4. A significant difference in spiking rate also was found between phasic and tonic REM states as well as between waking with eyes opened and closed in FoE recordings.Conclusions: Our data provide evidence of a discrepancy in spike distribution across different states of sleep and waking monitored by scalp and FoE recordings. We suggest that these discrepancies may reflect differences in archicortical and neocortical spike synchronization. Key Words: Mesial temporal lobe epilepsy-Sleep-Interictal spike-Foramen ovaleHippocampus.Sleep-related modulation of epileptic activity is a well-known common feature of different epilepsy syndromes. Non-rapid-eye-movement (NREM) sleep has been shown by most authors to activate interictal epileptic activity in both partial (1) and primary generalized epilepsy syndromes (2), whereas REM and waking has a contrary effect. Considerable controversy surrounds the issue of whether light NREM or deep NREM sleep exerts a stronger facilitatory effect on spiking. There is accumulating evidence that this may depend on the type of epilepsy syndrome being studied. According to recent spectral analysis results, a range of idiopathic childhood epileptic syndromes (3-8) can be characterized by increased spiking in the sigma range related to spindle synchronization present mainly during NREM2. Adult partial epilepsies, conversely, are accompanied by increased spiking related to the delta frequency range (9,10). The same tendency in spike activation was reported earlier by several visually scored studies (11-13) finding highest levels of spike activation during deep NREM stages in most temporal lobe epilepsy (TLE) patients. Nevertheless, both visually scored and spectralanalysis studies revealed small groups of patients deviating from this trend, exhibiting maximal spiking rates during light NREM, REM, or waking.A second point of controversy concerns the spiking properties of mesiotemporal structures. There are reports describing maximal spike activation mainly during deep NREM stages (11,12), whereas other authors described increased spiking mainly during light NREM stages ...

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Section: Figmentioning

confidence: 86%

Interictal Epileptic Spiking during Sleep and Wakefulness in Mesial Temporal Lobe Epilepsy: A Comparative Study of Scalp and Foramen Ovale Electrodes

et al. 2003

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“…Wyler (22) demonstrated that certain type of neurons were directly activated during sleep. Moreover, when interictal electrical activity from the deep temporal structures propagates to the scalp EEG, activation of neocortex has an important role (6,23). Increased neuronal synchronization within thalamocortical projection neurons during non-REM sleep contributes to the activating process in epileptic cortex (24).…”

Section: Discussionmentioning

confidence: 99%

Predictive Value of Interictal Epileptiform Discharges During Non‐REM Sleep on Scalp EEG Recordings for the Lateralization of Epileptogenesis

et al. 1998

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Summary:Purpose: EEG recording during sleep is widely used in the assessment of epilepsy, particularly in candidates for surgery, yet the diagnostic value of this procedure is not well established. We evaluated the predictive reliability of interictal epileptiform discharges (IEDs) for localization in presurgical patients with temporal lobe epilepsy (TLE) during non-REM sleep.Methods: Preoperative scalp EEG recordings with waking and sleep states were assessed in 83 patients with TLE in whom localization of the epileptogenic zone was subsequently confirmed by successful surgical treatment (patient seizure-free >1Results: The accuracy of EEG recordings for prediction of lateralization significantly changed from 5 1.8% during waking to 78.3% during sleep. After exclusion of patients who showed year). no discharges, the predictive value changed from 74.1 to 86.7%. However, in patients in whom the waking scalp EEG lateralized incorrectly, no improvement in reliability was achieved by sleep recording.Conclusions: Our results suggest that IEDs occurring in non-REM sleep provide more accurate information for lateralization of epileptogenesis than do those occurring during waking. This gain of diagnostic information was obtained in patients who showed either bilateral or no discharges in waking records, because unilateral discharges arising de novo in sleep were always correctly lateralizing. On the other hand, in patients who showed unilateral discharges in the awake state, whether ipsilateral or contralateral to the epileptogenic zone, the findings were generally unchanged during sleep. Key Words: Epilepsy-Electroencephalogram-Interictal discharge-Sleep.Sleep induction, achieved either by medication qr sleep deprivation, is a widely used method of EEG activation in clinical practice, because the frequency and extent of interictal epileptiform discharges (IEDs) .in the EEGs of people with epilepsy are generally increased in sleep (1-3). With a single waking EEG study, epileptiform discharges are detected in -50% of all patients with epilepsy (43). During sleep, epileptiform discharges appear in -80% (5).The region of IEDs does not always indicate the site of seizure onset (6). Patients with intractable epilepsy often show epileptiform discharges in regions more extensive than, and not necessarily contiguous to, the epileptogenic zone. Long duration of the illness and Iiigh seizure frequency may cause more complex pathophysiological phenomena, such as mirror foci or secondary epileptogenesis (7). Interictal or even ictal discharges in scalp recordings are variously estimated to have 6 6 9 5 % predictive reliability for the lateralization of epileptogenesis (8-12). Therefore, an increase in interictal discharges in sleep would not necessarily provide more reliable information for the localization and lateralization of epileptogenesis. However, few studies have addressed the localizing significance of epileptiform discharges in sleep.Some researchers believe that the localization of the epileptogenic zone by discharges in...

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“…Considerable additional information can be obtained by recording during drowsiness and sleep, especially about epileptiform discharges (Niedermeyer & Rocca 1972;Sato et al 1973). Some laboratories use sleep recording routinely.…”

Section: Recordingsmentioning

confidence: 99%

American Clinical Neurophysiology Society Guideline 1: Minimum Technical Requirements for Performing Clinical Electroencephalography

Sinha

Sullivan²,

Sabau

et al. 2016

The Neurodiagnostic Journal

149

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The Diagnostic Significance of Sleep Electroencephalograms in Temporal Lobe Epilepsy

Cited by 77 publications

References 0 publications

Interictal Epileptic Spiking during Sleep and Wakefulness in Mesial Temporal Lobe Epilepsy: A Comparative Study of Scalp and Foramen Ovale Electrodes

Interictal Epileptic Spiking during Sleep and Wakefulness in Mesial Temporal Lobe Epilepsy: A Comparative Study of Scalp and Foramen Ovale Electrodes

Predictive Value of Interictal Epileptiform Discharges During Non‐REM Sleep on Scalp EEG Recordings for the Lateralization of Epileptogenesis

American Clinical Neurophysiology Society Guideline 1: Minimum Technical Requirements for Performing Clinical Electroencephalography

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