Detection of epileptiform activity by different noninvasive EEG methods in complex partial epilepsy

Ambulatory EEG to Classify the Epilepsy Syndrome

SUMMARY

Recording of interictal epileptiform discharges to classify the epilepsy syndrome is one of the most common indications for ambulatory EEG. Ambulatory EEG has superior sampling compared with standard EEG recordings and advantages in terms of cost-effectiveness and convenience compared with a prolonged inpatient EEG study. Ambulatory EEG allows for EEG recording in all sleep stages and transitional states, which can be very helpful in capturing interictal epileptiform discharges. In the absence of interictal epileptiform discharges or in patients with atypical events, the characterization of an epilepsy syndrome may require recording of the habitual events. Diagnostic ambulatory EEG can be a useful alternative to inpatient video-EEG monitoring in a selected number of patients with frequent events who do not require medication taper or seizure testing for surgical localization.

Nasopharyngeal electrodes in temporal lobe epilepsy: A reappraisal of their diagnostic utility

OBJECTIVE

To compare electroencephalography (EEG) recordings with nasopharyngeal electrodes (NPEs) plus anterior temporal electrodes (ATEs) (NPE recordings) and those with only ATEs (non-NPE recordings) for the detection of interictal epileptiform discharges (IEDs) in patients with suspected temporal lobe epilepsy (TLE).

METHODS

We retrospectively analyzed the initial EEGs of 229 patients that were recorded simultaneously with ATEs and NPEs in addition to the electrodes of the 10-20 system of electrode placement. Two data sets of NPE and non-NPE recordings were reviewed independently by three interpreters with differing degrees of experience. Discordant findings in the interpretation among the three interpreters were resolved by a consensus to yield final results.

RESULTS

IEDs were detected in 76.4% of patients with NPE recordings compared to 55.5% with non-NPE recordings (p < 0.01). Bilateral independent IEDs were found in 26.2% and 11.4% of EEGs with NPE and non-NPE recordings (p < 0.01). The degree of agreement for the detection of IEDs among the three interpreters was higher with the NPE than with non-NPE recordings (κappa score, 0.70 vs. 0.54). The increased diagnostic yield of NPE recordings for the detection of IEDs was particularly prominent in patients with mesial and non-lesional TLEs.

CONCLUSIONS

EEG recordings using NPEs are useful to improve the sensitivity and level of agreement among interpreters for the detection of IEDs in patients with TLE.

SIGNIFICANCE

NPE recordings may be recommended in routine EEGs for the evaluation of patients with suspected TLE.

Electroencephalography source localization analysis in epileptic children during a visual working-memory task

We localize the sources of brain activity of children with epilepsy based on electroencephalograph (EEG) recordings acquired during a visual discrimination working memory task. For the numerical solution of the inverse problem, with the aid of age-specific MRI scans processed from a publicly available database, we use and compare three regularization numerical methods, namely the standardized low resolution brain electromagnetic tomography (sLORETA), the weighted minimum norm estimation (wMNE) and the dynamic statistical parametric mapping (dSPM). We show that all three methods provide the same spatio-temporal patterns of differences between the groups of epileptic and control children. In particular, our analysis reveals statistically significant differences between the two groups in regions of the parietal cortex indicating that these may serve as "biomarkers" for diagnostic purposes and ultimately localized treatment.

No Further Yield of Ambulatory EEG for Epileptiform Discharges Beyond 13 Hours

INTRODUCTION

This study aimed at evaluating the value added by 24-hour ambulatory EEG (AEEG) by comparing the presence of epileptiform discharges (EDs) between the first 30 minutes of recording versus the following 23.5 hours.

MATERIALS AND METHODS

A retrospective review of AEEGs of subjects divided into two groups, epilepsy and undiagnosed episodes of loss of consciousness, was conducted. AEEGs were divided into early EEG (E-EEG) (first 30 minutes) and extended EEG (remaining 23.5 hours). Extended EEGs were further divided into segments (S): 31st minute to 8th hour (SI), 9th to 16th hours (SII) and 17th to 24th hours (SIII). Each consecutive segment was reviewed to identify new EDs not seen previously.

RESULTS

Fifty-seven AEEGs were included, the median age being 36.3 years, the range being 18.7 to 78.6 years. There were 38 (66.6%) females. The collective yield of AEEG for detecting EDs was 19/57 (33.4%). The yield of E-EEG of new EDs was 5/57 (9%). During extended EEG, the distribution of EDs was as follows: SI, 12/55 (21.8%); SII, 2/43 (4.6%); and SIII 0/41 (0%). The yield, however, did not increase beyond the 13th hour. In undiagnosed episodes of loss of consciousness group (11), yield was 0/11 in all segments.

CONCLUSIONS

(1) There was no value added for yield of EDs by extending the EEG recording beyond 13 hours in epilepsy group. (2) The probability of capturing EDs is negligible if the clinical history does not clearly support the diagnosis of seizure or epilepsy.

Children with well controlled epilepsy possess different spatio-temporal patterns of causal network connectivity during a visual working memory task

Using spectral Granger causality (GC) we identified distinct spatio-temporal causal connectivity (CC) patterns in groups of control and epileptic children during the execution of a one-back matching visual discrimination working memory task. Differences between control and epileptic groups were determined for both GO and NOGO conditions. The analysis was performed on a set of 19-channel EEG cortical activity signals. We show that for the GO task, the highest brain activity in terms of the density of the CC networks is observed in α band for the control group while for the epileptic group the CC network seems disrupted as reflected by the small number of connections. For the NOGO task, the denser CC network was observed in θ band for the control group while widespread differences between the control and the epileptic group were located bilaterally at the left temporal-midline and parietal areas. In order to test the discriminative power of our analysis, we performed a pattern analysis approach based on fuzzy classification techniques. The performance of the classification scheme was evaluated using permutation tests. The analysis demonstrated that, on average, 87.6 % of the subjects were correctly classified in control and epileptic. Thus, our findings may provide a helpful insight on the mechanisms pertaining to the cognitive response of children with well controlled epilepsy and could potentially serve as "functional" biomarkers for early diagnosis.

Phenotypic characterisation of canine epileptoid cramping syndrome in the Border terrier

OBJECTIVES

To characterise the phenotype of Border terriers suspected to be affected by canine epileptoid cramping syndrome and to identify possible contributing factors.

METHODS

Owners of Border terriers with suspected canine epileptoid cramping syndrome were invited to complete an online questionnaire. The results of these responses were collated and analysed.

RESULTS

Twenty-nine Border terriers were included. Most affected dogs had their first episode before 3 years of age (range: 0·2 to 7·0 years). The majority of episodes lasted between 2 and 30 minutes (range: 0·5 to 150 minutes). The most frequent observations during the episodes were difficulty in walking (27 of 29), mild tremor (21 of 29) and dystonia (22 of 29). Episodes most frequently affected all four limbs (25 of 29) and the head and neck (21 of 29). Borborygmi were reported during episodes in 11 of 29 dogs. Episodes of vomiting and diarrhoea occurred in 14 of 29, with 50% of these being immediately before or after episodes of canine epileptoid cramping syndrome (7 of 14). Most owners (26 of 29) had changed their dog's diet, with approximately 50% (14 of 26) reporting a subsequent reduction in the frequency of episodes.

CLINICAL SIGNIFICANCE

This study demonstrates similarities in the phenotype of canine epileptoid cramping syndrome to paroxysmal dystonic choreoathetosis, a paroxysmal dyskinesia reported in humans. This disorder appears to be associated with gastrointestinal signs in some dogs and appears at least partially responsive to dietary adjustments.

Improved diagnosis in children with partial epilepsy using a multivariable prediction model based on EEG network characteristics

Background

Electroencephalogram (EEG) acquisition is routinely performed to support an epileptic origin of paroxysmal events in patients referred with a possible diagnosis of epilepsy. However, in children with partial epilepsies the interictal EEGs are often normal. We aimed to develop a multivariable diagnostic prediction model based on electroencephalogram functional network characteristics.

Methodology/Principal Findings

Routinely performed interictal EEG recordings at first presentation of 35 children diagnosed with partial epilepsies, and of 35 children in whom the diagnosis epilepsy was excluded (control group), were used to develop the prediction model. Children with partial epilepsy were individually matched on age and gender with children from the control group. Periods of resting-state EEG, free of abnormal slowing or epileptiform activity, were selected to construct functional networks of correlated activity. We calculated multiple network characteristics previously used in functional network epilepsy studies and used these measures to build a robust, decision tree based, prediction model. Based on epileptiform EEG activity only, EEG results supported the diagnosis of with a sensitivity and specificity of 0.77 and 0.91 respectively. In contrast, the prediction model had a sensitivity of 0.96 [95% confidence interval: 0.78–1.00] and specificity of 0.95 [95% confidence interval: 0.76–1.00] in correctly differentiating patients from controls. The overall discriminative power, quantified as the area under the receiver operating characteristic curve, was 0.89, defined as an excellent model performance. The need of a multivariable network analysis to improve diagnostic accuracy was emphasized by the lack of discriminatory power using single network characteristics or EEG's power spectral density.

Conclusions/Significance

Diagnostic accuracy in children with partial epilepsy is substantially improved with a model combining functional network characteristics derived from multi-channel electroencephalogram recordings. Early and accurate diagnosis is important to start necessary treatment as soon as possible and inform patients and parents on possible risks and psychosocial aspects in relation to the diagnosis.

Interictal EEG changes in patients with seizure disorder: experience in Bangladesh

The objective of this study was to determine the changes and sensitivity of electro encephalogram during interictal period and to evaluate the finding in the clinically suspected seizure events in a tertiary care hospital of Bangladesh. This cross sectional study was carried out in the Electrophysiology Laboratory of Dhaka Medical College Hospital from July 2010 to July 2011, which included 767 patients. EEG was obtained through scalp electrodes following international 10/20 system. Patient and their attendants were interviewed using a semi structured questionnaire. The EEG findings and clinical seizure events were then compared. Among the 767 epilepsy patients most were children (39.9% less than 10 years old) and young adult (33.2% in 11–20 years age group). Female patients predominantly had seizure than male (57% and 43% respectively). The overall sensitivity of EEG in yielding abnormal interictal epileptiform discharges was 62.7%. About 48.5% of them were diagnosed as localization related epilepsy and 11.7% were generalized epilepsy. Morphology showed spike and wave in 74% and sharp and wave in 11% tracings. Only 2% had slow waves. The presence of an interictal spike/sharp wave helps to confirm a clinical diagnosis of epilepsy, aids in defining the epilepsy syndrome, provides information that assists in planning drug management.

Electroencephalography in mesial temporal lobe epilepsy: a review

Electroencephalography (EEG) has an important role in the diagnosis and classification of epilepsy. It can provide information for predicting the response to antiseizure drugs and to identify the surgically remediable epilepsies. In temporal lobe epilepsy (TLE) seizures could originate in the medial or lateral neocortical temporal region, and many of these patients are refractory to medical treatment. However, majority of patients have had excellent results after surgery and this often relies on the EEG and magnetic resonance imaging (MRI) data in presurgical evaluation. If the scalp EEG data is insufficient or discordant, invasive EEG recording with placement of intracranial electrodes could identify the seizure focus prior to surgery. This paper highlights the general information regarding the use of EEG in epilepsy, EEG patterns resembling epileptiform discharges, and the interictal, ictal and postictal findings in mesial temporal lobe epilepsy using scalp and intracranial recordings prior to surgery. The utility of the automated seizure detection and computerized mathematical models for increasing yield of non-invasive localization is discussed. This paper also describes the sensitivity, specificity, and predictive value of EEG for seizure recurrence after withdrawal of medications following seizure freedom with medical and surgical therapy.

The role of the interictal EEG in selecting candidates for resective epilepsy surgery

The interictal EEG is a noninvasive and useful test for selecting candidates for resective epilepsy surgery, although it has many pitfalls. It is an essential test for the most common drug-resistant epilepsy, mesial temporal sclerosis, and predicts good outcome when interictal epileptiform discharges are concordant with unilateral hippocampal atrophy or sclerosis, and predicts poor outcome when interictal epileptic discharges are discordant with the lesion. Its role in other types of epilepsy surgery, including nonlesional cases and corpus callosotomy, is less clear. Future research gathering large multicenter prospective data is needed to maximize the role of this classic neurophysiological test in the evaluation of candidates for epilepsy surgery.

The yield of preoperative sequential routine scalp EEGs in patients who underwent anterior temporal lobectomy for mesial temporal sclerosis

Mesial temporal lobe epilepsy syndrome (MTLES) is the most common surgically remediable epileptic syndrome in adults. Its diagnosis is easy when clinical history is supported by positive laboratory findings. However, routine EEG may not be informative in some patients, thus delaying accurate diagnosis. Therefore, we sought to determine how often routine EEGs displayed epileptiform discharges pre-operatively in a group of patients who underwent surgery for MTLES. Retrospectively, we reviewed the outpatient EEG records of MTLES patients who underwent surgery at our epilepsy center between 1997-2008 and had at least one routine pre-operative EEG recording in our outpatient laboratory. For each patient, serial EEGs were coded as normal, displaying nonspecific abnormalities or lateralized and localized interictal epileptiform discharges. Seventy patients were included in the study. We reviewed 230 EEGs. In almost half of the patients (47.1%) all EEGs were normal or revealed nonspecific findings. In patients who had >1 EEG, almost 3 EEGs had to be recorded to detect the epileptiform discharges for the first time and 6.23 years were needed to accomplish this. Sleep deprivation considerably increased the yield. In summary, patients who have a clinical history suggesting MTLES may need at least 3 routine scalp EEG recordings (with at least one of them after sleep deprivation) to detect epileptiform abnormalities and it may take much time. Therefore, a single prolonged outpatient video-EEG monitoring or an overnight inpatient monitoring might be reasonable alternatives to serial EEGs.

Serum creatine phosphokinase is helpful in distinguishing generalized tonic-clonic seizures from psychogenic nonepileptic seizures and vasovagal syncope

OBJECTIVE

Distinguishing epileptic generalized tonic-clonic seizures (GTCS) from either psychogenic nonepileptic seizures (PNES) or vasovagal syncope (VVS) is important. In this study, we investigated the use of postictal serum creatine phosphokinase (CPK) concentrations in distinguishing between these events.

METHODS

Patients admitted to the Neurology Ward at Namazi Hospital in Shiraz, Iran, with an attack of transient loss of consciousness and abnormal movements witnessed by a neurologist were studied. We categorized the patients into three groups: 20 patients with GTCS, 22 with VVS, and 20 with PNES. A group of 20 normal healthy individuals were included in the study as the control group. Serum CPK concentration was measured 12-15 h after the attack in all patients and at one time in the control group. A P value less than 5% was considered significant.

RESULTS

There were no significant differences between the four groups with respect to age and sex. Mean CPK concentrations statistically significantly differed between the four groups, with higher levels in patients with GTCS (P=0.0001). Serum CPK concentration had a sensitivity of 75% and specificity of 86% for the diagnosis of GTCS. CPK concentration was above 160 mg/dl in 75% of patients with GTCS, 15% of patients with PNES, 13.6% of patients with VVS, and 15% of the control group (P=0.0001). The PNES, VVS, and control groups did not statistically significantly differ with respect to CPK concentrations.

CONCLUSION

In patients with a recent loss of consciousness and abnormal movements, serum CPK concentration is a useful, practical, and relatively accurate parameter to assist in the differentiation of epileptic seizures from either VVS or PNES.

Interictal EEG and the diagnosis of epilepsy

The interictal EEG provides information that aids in diagnosis and management of epilepsy. One must remember that the EEG is merely a tool, and its usefulness depends largely upon the skill of the individual who wields it. Like all diagnostic tests, it has significant limitations and cannot substitute for a careful history and exercise of good judgment. Nonetheless, in skilled hands, it provides unique and vital information in many patients, and enhances our understanding of their condition.

Management of dental patients with seizure disorders

Dental practitioners from time to time must treat patients with epilepsy or similar seizure disorders. This article describes the various classification for epilepsy, explains how such disorders are evaluated and diagnosed, discusses management methods, and addresses related issues for special populations, such as pregnant women and elderly. In addition, the article offers information about what special steps dentists should take in treating such epileptic patients and others vulnerable to seizures and in preparing offices and staff for the possibility that a patient will have a seizure in the office. In general, a patient with severe, poorly controlled epilepsy should be treated in a hospital. Otherwise, a well-controlled patient should easily be treated in the office.

Frontal lobe seizures

Despite the fact that clinical characteristics of frontal lobe seizures have been recently described better, differentiating seizures of frontal lobe origin from NES on clinical grounds alone is difficult. The difficulty has been compounded by the fact that both inter-ictal and ictal EEG can be normal or nonspecific, and the same is true of imaging studies. A detailed clinical history as well as video monitoring can be helpful diagnostic tools. A multidisciplinary approach is warranted and is at times essential to improve the diagnosis and care of these difficult patients.

Clinical neurophysiology of epilepsy

Electroencephalography (EEG) continues to be the most important diagnostic tool in the management of patients with epilepsy. In particular, the high specificity of interictal epileptiform discharges makes scalp EEG a valuable tool in the evaluation of patients with a history of seizures or seizure-like episodes. Advances in technology, most notably the development of digital video-EEG, have significantly expanded the utility of EEG. In addition to the routine EEG, long-term monitoring studies including video-EEG, ambulatory EEG, and continuous EEG monitoring play important roles in various aspects of the diagnosis and treatment of epilepsy. Recent developments in computerized seizure detection and prediction algorithms, particularly those utilizing intracranial EEG electrodes, hold promise for future development of novel treatment strategies.

Role and limitations of routine and ambulatory scalp electroencephalography in diagnosing and managing seizures

The scalp electroencephalogram (EEG) is the cornerstone in the diagnosis and treatment of seizure disorders. The EEG, with its excellent temporal resolution, provides a direct measurement of cortical electrophysiology, revealing, for example, the presence of interictal epileptiform discharges that identify regions of an epileptogenic brain. We define the EEG characteristics of focal and generalized epileptiform discharges and provide evidence for their varying diagnostic importance in different patient populations. Identification of nonepileptiform EEG transients, such as wicket waves, small sharp spikes,rhythmic temporal theta activity, and 14- and 6-Hz positive bursts, that can be confused for epileptiform transients is emphasized. A final point is that the clinician must interpret EEG findings within the overall clinical context.

Sensitivity of recordings at sphenoidal electrode site for detecting seizure onset: evidence from scalp, superficial and deep foramen ovale recordings

OBJECTIVES

Some authors have recently stressed that the position of the tip of sphenoidal electrodes plays a crucial role in their efficacy in detecting ictal onset. An opportunity to test this hypothesis is provided by recordings from the most superficial contacts of foramen ovale (FO) electrode bundles because these contacts are located at the FO, in a position equivalent to that of optimally located sphenoidal electrodes. To simplify wording, recordings obtained by superficial FO electrodes will hereafter be called sphenoidal recordings, although they have not been obtained with standard sphenoidal electrodes. The sensitivities of simultaneous scalp and sphenoidal recordings for detecting ictal onset have been compared with each other, and with a 'gold standard' provided by simultaneous deep intracranial FO recordings from the mesial aspect of the temporal lobe.

METHODS

Three hundred and fourteen seizures obtained from 110 patients under telemetric presurgical assessment for temporal lobe epilepsy have been studied. Scalp electrodes included anterior temporal placements. All scalp electrodes were considered when identifying seizure onset but the anterior temporal electrodes were most frequently involved.

RESULTS

Ictal onset time at sphenoidal and scalp recordings: initial ictal changes appeared simultaneously in scalp and sphenoidal recordings in 123 seizures (39.2%). Initial changes occurred earlier in sphenoidal recordings in 63 seizures (20.1%), whereas they were seen earlier on the scalp in 76 seizures (24.2%). Artefacts prevented the comparison between sphenoidal and scalp recordings in 16 seizures (5.1%) and no ictal changes were seen on the scalp and/or sphenoidal recordings in 36 seizures (11.5%). In most of the 63 seizures where ictal changes appeared earlier in sphenoidal recordings, a delayed ipsilateral scalp onset was seen as the signal amplitude increased or scalp changes could be identified retrospectively on the scalp with an onset which appeared simultaneous and ipsilateral to the initial sphenoidal changes. Sphenoidal recordings supplied additional information when compared to scalp recordings in only 22 seizures (7%): in 5 seizures with artefacts on the scalp, in 6 seizures with no changes on the scalp and in 11 seizures with discrepant laterality at onset. Congruence in laterality with respect to deep intracraneal FO recordings: of the 61 seizures with unilateral onset on the scalp, onsets at sphenoidal recordings and deep FO electrodes were ipsilateral in most cases. In only 3 of these 61 seizures (4.9%), sphenoidal recordings lateralized ipsilateral to the deep FO electrodes in the presence of a contralateral onset on the scalp. In 14 among the 122 seizures (11.5%) with bilateral asymmetrical onset on the scalp, sphenoidal recordings lateralized seizure onset ipsilateral to the deep FO electrodes in the presence of a contralateral scalp onset. Thus, when compared with scalp EEG, sphenoidal recordings increased laterality congruence with respect to deep FO electrodes in 17 seizures (5.4%).

CONCLUSIONS

Extracranial electrodes located next to the FO at the sphenoidal electrode site yield an improvement over suitable surface electrodes in the identification of ictal onset in only 5.4-7% of seizures. Such improvement derives from the fact that the low amplitude signals often seen at seizure onset may show higher amplitude on sphenoidal than on scalp recordings.

Comparison of sphenoidal, foramen ovale and anterior temporal placements for detecting interictal epileptiform discharges in presurgical assessment for temporal lobe epilepsy

OBJECTIVES

Some authors have recently stressed that the position of the tip of the sphenoidal electrode plays a crucial role in its efficacy to detect mesio-basal spikes. We have tested this hypothesis by comparing the sensitivity of a contact of a foramen ovale bundle located at the foramen ovale (CFO) with scalp electrodes in detecting interictal epileptiform discharges. We have also compared deep and superficial foramen ovale contacts in the same bundle in order to establish whether deeper contacts can detect epileptiform discharges not seen at the foramen ovale or on the scalp.

METHODS

The sensitivity for detecting epileptiform discharges of simultaneous intracranial and scalp EEG recordings from 20 patients under telemetric presurgical assessment for temporal lobe epilepsy were compared.

RESULTS

Out of 2280 epileptiform discharges evaluated, about 70% were seen only at the deep foramen ovale contacts. Out of the 722 discharges recorded by CFO and/or scalp electrodes, 698 were seen at the CFO and 690 at the scalp anterior temporal electrode. Only on 29 occasions (4.15%) were discharges recorded at the CFO and not at the anterior temporal electrode. On 21 occasions (3.04%) CFO failed to detect discharges seen at the anterior temporal electrode.

CONCLUSIONS

Our findings confirm previous results suggesting that sphenoidal electrodes, however accurately positioned, offer no significant increase in detection sensitivity compared with anterior temporal scalp electrodes. In addition, these results confirm that a large proportion of discharges seen at the deepest foramen ovale contacts are not seen either on the scalp nor at the superficial foramen ovale contacts.

Usefulness of latero-orbital electrodes in detecting interictal epileptiform activity--a study of 60 patients with complex partial seizures

OBJECTIVES

The use of latero-orbital (Lo) electrodes is a routine practice in any EEG laboratory to evaluate eye motion, but there are no data about their usefulness in revealing interictal epileptiform abnormalities.

METHODS

In 60 consecutive patients (27 men, 33 women, mean age 36.8 years, range 17-72) with complex partial seizures, we prospectively evaluated the utility of Lo electrodes in comparison with anterior temporal (AT) electrodes, for the detection of interictal epileptiform discharges (SW).

RESULTS

No epileptiform abnormality was seen in 4/60 patients. Both AT and Lo electrodes were significantly superior to 10-20 electrodes for detection of both patients and foci. Indeed, the standard 10-20 system alone allowed the detection of only 39 independent epileptiform foci in 35/56 (63%) patients, while AT and Lo electrodes were necessary for detection of 23 epileptiform foci in the remaining 21/56 (37%) patients. Importantly, there was no statistically significant difference in detection between AT and Lo electrodes.

CONCLUSIONS

Recordings from Lo electrodes are comparable to those from AT electrodes and are useful for localizing interictal temporal spiking activity. Lo electrodes may be substituted for basal electrodes in the day-to-day evaluation of patients with complex partial seizures.

Incidence of spikes and paroxysmal rhythmic events in overnight ambulatory computer-assisted EEGs of normal subjects: a multicenter study

The incidences of spikes and paroxysmal rhythmic events (PREs) in 10-h overnight EEGs of normal adult volunteers (n=135) were studied at 11 sites with a computer-assisted ambulatory EEG monitoring system with automatic spike and PRE detection. Spikes were evident in the overnight EEG of 1 subject (0.7%), and PREs were apparent in the overnight EEG of the same subject (0.7%). The incidences of spikes of 24 other subjects with a history of migraine and/or a family history of epilepsy were 12.5 and 13.3%, respectively. The overnight EEGs of these subjects were significantly more likely to show spikes than the overnight EEGs of subjects without migraine or a family history of epilepsy.

Tachykinins, neurotrophism and neurodegenerative diseases: a critical review on the possible role of tachykinins in the aetiology of CNS diseases

The tachykinins are a family of undecapeptides that are widely distributed throughout the body, including the central nervous system (CNS). They have several well defined roles in non-CNS sites as well as in the dorsal horn, where they are involved in the transmission of nociceptive information. However their function(s) in other CNS sites is unclear, but there is some evidence that they function as neuromodulators rather than neurotransmitters. This neuromodulation includes a possible role in maintaining the integrity of neuronal populations, analogous to the functions of neurotrophic factors. This review critically evaluates the role of tachykinins as neurotrophic factors, with particular reference to the common neurodegenerative diseases of the CNS.

Comparison of coronal sphenoidal versus standard anteroposterior temporal montage in the EEG recording of temporal lobe seizures

Chronic sphenoidal electrodes were developed to facilitate the recording and localization of temporal lobe seizures during long term monitoring. Many reports demonstrate their utility in displaying temporal interictal epileptiform activity, but there have been few direct comparisons of sphenoidal electrodes and surface temporal recordings actually. We compared simultaneous portions of 74 EEG recordings of temporal lobe seizures (from 42 patients), with one portion including sphenoidal electrodes in a coronal montage and one with a standard anterior posterior temporal montage. Separated tracings were reviewed by readers blinded to the other portion of the tracing. The coronal sphenoidal montage allowed recognition of temporal lobe seizures inapparent with standard surface temporal electrodes in 19% of seizures and led to an earlier identification (usually by > or = 5 s) of the onset in 70% of seizures. Indwelling, flexible sphenoidal electrodes assist in ambulatory recording of temporal lobe seizures, both in demonstrating the presence of seizures and in determining the localization and time of seizure onset.

Extracranial EEG work-up in epilepsy surgery: usefulness and limitations

Extracranial interictal and ictal EEG provide essential information to diagnosis, seizure/syndrome classification and focus localization. Combined with structural and dynamic neuro-imaging and neuropsychological data, extracranial EEG will often provide sufficient information in preoperative work-up for temporal lobectomy. Ictal EEG recordings are essential to confirm the diagnosis and classification and, above all, to exclude patients with significant non-epileptic seizures from further surgical evaluation. The advantage of sphenoidal electrodes lies first and foremost in a more favorable signal/noise ratio, while their superiority to closely placed special scalp electrodes are more debatable.

Effect of barbiturate on epileptiform activity: comparison between intravenous and oral administration. Sphenoidal, zygomatic and temporal recordings

The present study was performed in order to compare: 1) the differences between oral and intravenous barbiturate on interictal epileptiform activity (sharp-waves and spikes) in the EEG, and 2) interictal epileptiform activity in the sphenoidal electrode compared to the temporal and zygomatic electrodes (an electrode placed at the cutaneous entry of the sphenoidal electrode) during intravenous barbiturate administration in patients with epilepsy. Two procedures were performed: 1) an oral pentobarbital sleep induction with 10-20 electrode placement including a zygomatic electrode, and 2) an intravenous thiopental sleep induction with the same electrode placement including a sphenoidal electrode. Thirty eight patients with complex partial seizures were included. During the oral pentobarbital procedure 34 of 38 (90%) patients showed interictal epileptiform activity compared with 22 of 38 (55%) patients during the intravenous thiopental procedure (p < 0.005). A interictal epileptiform focus was observed in 33 (87%) patients in the oral procedure and in 19 (50%) patients in the intravenous procedure (p < 0.01). Interictal epileptiform activity recorded in the sphenoidal electrode was also recorded in the zygomatic electrode. Except from two patients a good correlation was observed between the zygomatic electrodes and the F7/F8 electrodes. We conclude that administration of intravenous thiopental offers no advantage compared to the administration of oral pentobarbital as an activating procedure, and for standard interictal EEG recordings with sleep activation procedures, suitable places scalp electrodes including a zygomatic electrode with the use of oral pentobarbital may be sufficient.

Surface sphenoidal electrode for recording anterior temporal spikes

Spike analysis was performed to determine if surface sphenoidal electrodes were suitable substitutes for depth sphenoidal or anterior temporal electrodes in outpatient EEG recordings for the diagnosis of complex partial seizures of anterior temporal origin. Spike measurements consisted of spike detection rate, spike amplitude, and location of maximal amplitude spikes. Depth sphenoidal electrodes had the highest yield in these three measurements. Surface sphenoidal electrodes did not differ from anterior temporal electrodes in spike detection rate and spike amplitude, but the former recorded almost no maximal amplitude spikes, while the latter had approximately 30% of the maximal spikes. It is concluded that surface sphenoidal electrodes are slightly inferior to anterior temporal electrodes, but the differences between them are minimal for practical purposes in outpatient EEG recordings.