Ilse Wambacq

The diagnostic value of EEGs in patients with syncope.

We retrospectively reviewed reports of all EEGs performed at the New Jersey Neuroscience Institute at JFK Hospital between January 1999 and December 2003. Of 9234 EEGs performed, 1094 were of patients with syncope. Among patients with syncope, 67.18% of the EEGs were normal and 28.15% showed diffuse and focal slowing. Only 1.46% of the EEGs showed epileptiform discharges (EDs). This is similar to the incidence of EDs in healthy adults. The presence of EDs did not change the management of these patients. Therefore, EEGs have very low yield and should not be routinely obtained in patients with syncope.

Non-voluntary and voluntary processing of emotional prosody: an event-related potentials study

The present study investigated whether event-related potentials (ERPs) reflect non-voluntary vs voluntary processing of emotional prosody. ERPs were obtained while participants processed emotional information non-voluntarily (i.e. while evaluating semantic characteristics of a stimulus) and voluntarily (i.e. while evaluating emotional characteristics of a stimulus). Results suggest that emotional prosody is processed around 160 ms after stimulus onset under non-voluntary processing conditions (when the attention is diverted from the emotional meaning of the tone of voice); and around 360 ms under voluntary processing conditions. The findings support the notion that emotional prosody is processed non-voluntarily in the comprehension of a spoken message.

Long-term outcome of vagus nerve stimulation therapy in patients with refractory epilepsy

We retrospectively assessed the long-term efficacy of vagus nerve stimulation (VNS) therapy in 31 patients with refractory partial and generalized seizures who were not candidates for resective epilepsy surgery. Following implantation of VNS there was significant improvement in seizure frequency at 6 months. Sixteen patients continued to have sustained response to VNS therapy 4 years later. Adverse effects of VNS therapy were transient and tolerable. The majority of the patients did not gain body weight and some of them had significant weight loss. Therefore VNS is safe and effective therapy and has a long-term sustained effect in refractory epilepsy.

Seizures in the elderly: Video/EEG monitoring analysis

OBJECTIVE Recently there has been a remarkable increase in the number of elderly people with epilepsy due to the growing size of this segment of the population. The literature provides little information on the characteristics of epileptic and nonepileptic events in the elderly. Therefore we report the results of video/EEG recordings in patients aged 60 or older admitted over 2 consecutive years to an epilepsy monitoring unit (EMU). METHODS We examined the records of all elderly patients admitted to our EMU between December 1999 and December 2001. Fifty-eight patients were older than 60, constituting 17% of the total admissions to the EMU. All patients underwent continuous video/EEG monitoring. On the basis of reasons for admission, video/EEG reports were categorized into (1) diagnosis of events, (2) characterization and localization of seizures, (3) adjustment of medication, and (4) status epilepticus (nonconvulsive). RESULTS There were 26 women between the ages of 60 and 91 and 32 men between the ages of 60 and 84. The main reasons for admission were diagnosis of events (57% of patients), followed by characterization and localization of events (36% of patients). There were 6 patients with psychogenic nonepileptic seizures (PNES); 5 were women and 4 of them were >70 years of age. All PNES patients presented with motor symptoms, except for an 87-year-old man who presented with abdominal spasm. Two of these six patients were suspected of having PNES before admission. Two patients were admitted with suspicion of status epilepticus, but neither proved to have status epilepticus. The most frequent diagnosis was physiologic nonepileptic seizures (26 patients; 45%), and 27% of these patients were on antiepileptic drugs, which were discontinued after the diagnosis of nonepileptic seizures. Complex partial seizure was the most frequent seizure type, occurring in 23 patients, 6 of whom (27%) had both complex partial seizures and secondarily generalized seizures. CONCLUSION In the elderly, video/EEG results in a definitive diagnosis in the majority of cases and can assist in the decision whether antiepileptic drugs are necessary. PNES can occur in the elderly, and video/EEG monitoring can facilitate their recognition and management.

The localizing value of auditory event-related potentials (P300) in patients with medically intractable temporal lobe epilepsy

The localizing value of postictal versus interictal event-related potentials (ERPs) was studied in patients with medically intractable TLE admitted for long-term video EEG monitoring. Ten patients with partial seizures and secondary generalization underwent preictal (upon hospital admission), postictal (</=6h after seizure), and interictal (7-48h after seizure) ERP recordings of an auditory oddball paradigm. Preictal ERPs were compared to postictal and interictal recordings. Intraclass correlations, transformed into z scores, were utilized to analyze amplitude differences between electrodes placed on the hemisphere ipsilateral versus contralateral to the epileptogenic focus. The results showed that in 9 out of 10 patients the ERP amplitude was reduced in postictal compared to preictal recordings for electrodes placed ipsilateral to the epileptogenic focus (P<0.0001). However, there was no difference in amplitude between ipsilateral and contralateral electrodes in preictal and interictal recordings. These findings suggest that postictal ERPs are of localizing value in patients with TLE while interictal ERPs are not.

The efficacy of routine hyperventilation for seizure activation during prolonged video-electroencephalography monitoring.

Hyperventilation (HV) is considered to be one of the activation procedures that provokes epileptic potentials and clinical seizures. However, the true clinical yield of HV is not well established. We retrospectively reviewed the records of all patients admitted to JFK Hospital, Edison, New Jersey, between October 2001 and December 2004 for long-term video-electroencephalography (EEG). A total of 475 patients (193 males; 282 females; age range 5-89 years) were included in the study. All patients underwent routine 3-minute HV as part of the evaluation of their clinical episodes. During the initial assessment, 165 patients did not experience a seizure event, 92 had non-epileptic events, 16 experienced psychogenic non-epileptic seizures (PNES) and six had a clinical event. During HV, of the 43 patients who had primary generalized epilepsy, nine had an abnormal EEG and two experienced seizures; however, out of the 159 patients who had partial seizures, only one patient demonstrated an abnormal EEG. Our study demonstrates that routine HV generally has a very low yield in our Epilepsy-Monitoring Unit. This finding also lends support to the idea that partial seizures are relatively resistant to HV activation.

Neural indices of spoken word processing in background multi-talker babble

Abstract Objective: To evaluate the impact of multi-talker babble on cortical event-related potentials (ERPs), specifically the N400, in a spoken semantic priming paradigm. Design: Participants listened in quiet and with background babble to word triplets, evaluating whether the third word was related to the preceding words. A temporo-spatial principal component analysis was conducted on ERPs to the first and second words (S1 and S2), processed without an overt behavioral response. One factor corresponded to the N400 and revealed greater processing negativity for unrelated as compared to related S2s in quiet and in babble. Study sample: Twelve young adults with normal hearing. Results: Background babble had no significant impact on the N400 in the posterior region but increased neural processing negativity at anterior and central regions during the same timeframe. This differential processing negativity in babble occurred in response to S2 but not S1. Furthermore, background babble impacted processing negativity for related S2s more than unrelated S2s. Conclusions: Results suggest that speech processing in a modestly degraded listening environment alters neural activity associated with auditory working memory, attention, and semantic processing in anterior and central scalp regions. Sumario Objetivo: Evaluar el impacto del balbuceo de múltiples hablantes en los potenciales corticales relacionados con eventos (ERP), específicamente el N400, en un paradigma de habla de base semántica. Diseño: Los participantes escucharon en silencio y con balbuceo de fondo, tripletas de palabras, para evaluar si la tercera palabra estaba relacionada con las palabras precedentes. Se realizó el análisis témporo-espacial del componente principal sobre los ERPs, en las palabras primera y segunda (S1 y S2), procesadas sin una respuesta conductual manifiesta. Un factor correspondió al N400 y reveló una negatividad de procesamiento para la no relacionada, en comparación con la S2 relacionada, tanto en silencio como con balbuceo. Muestra de Estudio: Doce adultos jóvenes con audición normal. Resultados: El balbuceo de fondo no tiene un impacto significativo en el N400 en la región posterior pero aumentó la negatividad de procesamiento en las regiones anterior y central durante el mismo marco temporal. Esta diferente negatividad diferencial de procesamiento con balbuceo, ocurrió en respuesta a S2 pero no a S1. Más aún, el balbuceo de fondo impactó la negatividad de procesamiento para las S2 relacionadas, más que para las S2 no relacionadas. Conclusiones: Los resultados sugieren que el procesamiento del lenguaje en un ambiente de escucha modestamente degradado, altera la actividad neural asociada con la memoria auditiva activa, la atención y el procesamiento semántico en las regiones anterior y central de la cabeza.

The presence of polyglucosan bodies in temporal lobe epilepsy: its role and significance

RATIONALE Mesial temporal sclerosis (MTS) is an important pathology in temporal lobe epilepsy (TLE) and often associated with good surgical outcome, however prognostic factors for surgical outcome are conflicting. The authors examine seizure outcome after surgery for TLE due to MTS, with focus on the presence of polyglucosan bodies (PGBs), and its relation to the epileptogenic process. METHODS Records of 44 consecutive patients with intractable TLE who underwent anterior temporal lobectomy (ATL) at JFK medical center between 1994-2001 were reviewed. Details of clinical, electrophysiological evaluation, and outcome were collected. All slides were reviewed for the presence of MTS. In twenty-one patients with MTS, detailed histology of surgical specimens was reviewed and relative concentration of PGBs was assessed. The postoperative follow-up duration ranges between 28-74 months. Surgical outcome was evaluated according to Engels classification. RESULTS Data of fourteen females (mean age 32.8 years) and 7 males (mean age 34.2) were analyzed. PBGs were identified in 10 patients (8 females and 2 males). All 10 patients had good surgical outcome, with 6 patients (60%) being seizure free (class 1) and 4 patients as class 2. While 11 patients (6 males and 5 females) with absent PGB, 72.8% had good surgical outcome. Of these, 7 (63.8%) had class 1, 1 patient had class 2, and 3 patients had class 3&4. Assessing several risk factors, the only significant difference between the two groups was epilepsy duration, which was significantly longer in patients with PGBs (P = 0.011). CONCLUSION The histological presence of PGB is associated with long duration of epilepsy and could be the consequence of epilepsy. Despite prolonged duration of epilepsy, the surgical outcome in PGBs +ve is similar to PGBs -ve patients.

The effect of background babble on working memory in young and middle-aged adults.

BACKGROUND Background noise has been found to negatively affect working memory. Numerous studies have also found that older adults perform more poorly on working memory tasks than young adults (YA). Hearing status has often been a confounding factor in older individuals. Therefore, it would be beneficial to investigate working memory functions in adverse listening conditions early in the aging process (i.e., middle-age), when hearing function is relatively unaffected. PURPOSE The focus of this study was to determine the influence of background babble on working memory in YA and middle-aged adults (MA) with normal hearing. RESEARCH DESIGN Before testing was begun, we established that all participants could correctly identify words in a degraded experimental testing environment with 100% accuracy. Then, the participants listened to lists composed of five pairs of words in quiet and in 20-talker babble. After the final word pair, the participants were cued with the first word of one of the previous five word pairs. The participants were required to write down the second word of the pair. The percent correct scores for each of the five serial positions were analyzed comparing the two listening conditions for YA and MA. Ten YA and ten MA with normal hearing between 250-8000 Hz and a score of at least 26/30 on the Mini-Mental State Examination participated in the study. As different cognitive processes are used for initial, middle, and final serial positions, averaged scores were obtained for Positions 2 and 3 and for Positions 4 and 5. Subsequently, repeated-measures analyses of variance (ANOVAs) were conducted on mean scores of correctly recalled word pairs with serial positions (initial, middle, and final) and listening condition (quiet, babble) as the within-participant variables and age group (YA, MA) as the between-participant independent variable. This OMNIBUS repeated-measures ANOVA was then followed up with separate repeated-measures ANOVAS for the initial, middle, and final positions. RESULTS Correct recall scores were lower for early positions compared with the latter positions, irrespective of listening condition. For Position 1, YA-but not MA-performed significantly better in babble than in quiet. For the middle positions (Positions 2 and 3), MA performed significantly more poorly than the YA irrespective of listening condition. For the final positions (Positions 4 and 5), no age differences or effects of listening condition were found. CONCLUSIONS The results indicate that both YA and MA have trouble recalling earlier pieces of information in quiet and in babble. However, MA exhibited significantly poorer recall scores than YA in babble for Position 1, which suggest that cognitive processes related to memory encoding and retrieval are different in background babble for MA and YA.

Auditory event-related potentials (P300) in the identification of psychogenic nonepileptic seizures

The feasibility and conceivable value of postictal event-related potential (ERP) recordings were studied in patients with nonepileptic seizures (NES) admitted for long-term video/EEG monitoring. Ten patients with NES underwent preictal (on hospital admission) and postictal (< or =6 hours after seizure) ERP recordings of an auditory oddball paradigm. Additionally, 10 temporal lobe epilepsy (TLE) patients with partial seizures and secondary generalization underwent preictal, postictal (< 6 hours after seizures), and interictal (7-48 hours after seizure) ERP recordings. We recently reported that ERPs recorded in TLE patients with partial epilepsy undergo a temporary change postictally, while returning to their preictal state during interictal recordings. In the current study intraclass correlations, transformed into z scores, are used to determine test-retest validity of repeated ERP recordings. An independent sample t test with z scores for the comparison of preictal and postictal recordings showed that ERP activation differed between NES and TLE patients (P=0.009). More specifically, ERP recordings in the preictal and postictal states were similar in NES patients, but dissimilar in TLE patients. On the other hand, this dissimilarity in ERPs disappeared when comparing z scores for the preictal and postictal recordings in NES patients with z scores for the preictal and interictal recordings in TLE patients. This further supports the notion that identical waveforms during preictal and postictal recordings in NES patients reflect nonepileptic seizure activity. The current findings suggest that postictal ERP recordings are useful in the diagnosis of NES and differentiate TLE from NES.