SPECT in the localisation of extratemporal and temporal seizure foci.

The yield of ictal, postictal, and interictal SPECT was compared in the localisation of seizure foci in 177 patients with partial epilepsy. In 119 patients with known unilateral temporal lobe epilepsy ictal SPECT (97% correct localisation) was superior to postictal SPECT (71% correct), which was better than interictal studies (48% correct). Similarly, in cases of known or suspected extratemporal epilepsy the yield of ictal SPECT studies was high (92%). By contrast, the yield of postictal studies was much lower (46%) and usually only very early postictal studies were diagnostic. Interictal SPECT was of little value. The accuracy of ictal SPECT in localising temporal lobe seizures is now well established. Extratemporal seizures are often brief and difficult to localise. This report shows that ictal SPECT also has a high diagnostic yield in a wide range of extratemporal epilepsies. The brevity of many extratemporal seizures means that true ictal SPECT examinations can be difficult to achieve, but the high diagnostic yield justifies the special organisational effort needed to obtain such studies.     

Ictal magnetoencephalography in temporal and extratemporal lobe epilepsy

PURPOSE: We evaluated visual patterns and source localization of ictal magnetoencephalography (MEG) in patients with intractable temporal lobe epilepsy (TLE) and extratemporal epilepsy (ETE). METHODS: We performed spike and seizure recording simultaneously with EEG and MEG on two patients with TLE and five patients with ETE. Scalp EEG was recorded from 21 channels (10-20 international system), whereas MEG was recorded from two 37-channel sensors. We compared ictal EEG and MEG onset, frequency, and evolution and performed MEG dipole source localization of interictal spikes and early ictal discharges and co-registered dipoles to brain magnetic resonance imaging (MRI). We correlated dipole characteristics with intracranial EEG, surgical resection, and outcome. RESULTS: Ictal MEG lateralized seizure onset in both TLE patients and demonstrated ictal onset, frequency, and evolution in accordance with EEG. Ictal MEG source analysis revealed tangential vertical dipoles in the anterolateral angle in one patient, and anterior dipoles with anteroposterior orientation in the other. Intracranial EEG revealed regional entorhinal seizure onset in the first patient. Both patients became seizure free after temporal lobectomy. In ETE, ictal MEG demonstrated visual patterns similar to ictal EEG and had concordant localization with interictal MEG in all five patients. Two patients underwent surgery. Ictal MEG localization was concordant with intracranial EEG in both cases. One patient had successful outcome after surgery. The second patient did not improve after limited resection and multiple subpial transections. CONCLUSIONS: Ictal MEG can demonstrate ictal onset frequency and evolution and provide useful localizing information before epilepsy surgery.     

Ictal asystole mimicking seizure deterioration in temporal lobe epilepsy

We report on a patient with temporal lobe epilepsy, secondary to a left lateral temporal cavernoma, in whom the change in seizure semiology suggested recurrence of secondary generalized seizures. Anticonvulsive medication previously controlled secondary generalized seizures over a period of years but focal seizures continued at a lower rate. Continuous video‐EEG monitoring revealed ictal asystole associated with myoclonic syncope and falls during focal seizures arising from the left temporal lobe. After implantation of a cardiac pacemaker, no more falls occurred during the focal seizures. In conclusion, recurrence of seizure‐associated falls is typically attributed to recurrence of secondary generalized seizures, however, ictal asystole should be considered in selected epilepsy patients as a differential diagnosis of falls. [Published with video sequence]     

Mood disturbance before and after seizure surgery: a comparison of temporal and extratemporal resections

PURPOSE: Mood disturbance is a common comorbid condition of temporal lobe epilepsy before and after seizure surgery. Few studies have examined mood disturbance in patients undergoing resections outside the temporal lobe (extratemporal resections). This study aimed to compare the early, postoperative evolution of mood disturbance in temporal and extratemporal lobe epilepsy patients to examine the effect of site of surgical resection on mood outcome. METHODS: The study used a longitudinal design and was qualitative in nature. Sixty seizure surgery patients (43 temporal resections, 17 extratemporal resections) were assessed before surgery and at discharge, 1 month, and 3 months after surgery, by using the Austin CEP Interview. Psychosocial adjustment, psychiatric difficulties, including depression and anxiety, and seizure frequency were assessed. RESULTS: Before surgery, both temporal and extratemporal patients had significant psychiatric histories with similarly high rates of depression (33 and 53%, respectively) and anxiety (23 and 18%, respectively). After surgery, significantly more temporal patients were seizure free at each of the reviews compared with extratemporal patients. Temporal patients also reported significantly higher levels of depression (26%), anxiety (42%), and psychosocial adjustment difficulties (64%) at the 1-month review than did extratemporal patients. Mood disturbance was significantly associated with adjustment difficulties in both groups, but was not related to seizure outcome at any review period. CONCLUSIONS: A general increase in mood disturbance was evident after surgery, particularly in temporal resection patients at the 1-month review. Site of surgery and psychosocial adjustment showed significant associations with postoperative mood disturbance, supporting the role of both neurobiological and psychosocial factors in mood outcome.     

Ictal urinary urge indicates seizure onset in the nondominant temporal lobe

ARTICLE ABSTRACT: The authors describe six patients with medically refractory temporal lobe epilepsy whose seizures were characterized by an aura of ictal urinary urge. All seizures originated in the nondominant temporal lobe as evidenced from interictal spikes, ictal EEG, and MRI. Ictal SPECT, which was obtained in two patients, showed a hyperperfusion of the insular cortex, indicating a critical role of the insula for the generation of this symptom. Ictal urinary urge represents a new lateralizing sign indicating a seizure onset in the nondominant temporal lobe.     

Ictal EEG wave forms from epidural electrodes predictive of seizure control after temporal lobectomy.

Ictal wave form characteristics--frequency, spatial distribution, and duration--were analyzed for 140 complex partial seizures recorded from epidural strip electrodes implanted in 28 patients. None had abnormalities on imaging studies. All had bilateral electrode placements, unilateral seizure onsets, temporal lobectomies, and were followed for a mean of 33 months postoperatively. Sixteen patients (57%) became free of complex partial seizures: 12 had reductions in seizure frequency of at least 50% but were not seizure-free. The only predictor of the seizure-free state was the presence of low voltage fast activity (LVF), in the alpha or beta ranges, localized to one gyrus. This phenomenon occurred in 14/16 seizure-free patients, 2/12 of others (P < 0.001). As seizures progressed, LVF typically increased in amplitude, propagated, and slowed into the theta range. Wave forms were classified into 8 categories based upon their frequency and morphology. Stepwise discriminant analysis of these wave forms, with consideration of whether they were localized or regional, revealed that both frequency and localization were critical for the post-surgical prognosis. The mere presence of a localized seizure onset was unreliable unless the wave form was taken into account. Well-localized rhythmic activity over 8 Hz at seizure onset from epidural subtemporal electrodes predicts surgical success. Slower rhythms imply greater separation in space and time from seizure onset.     

Ictal pallor is associated with left temporal seizure onset zone in children

PURPOSE: To describe the frequency, localizing and lateralizing value of ictal pallor (IP) in children with focal epilepsy. METHODS: A retrospective review of medical charts and 514 archived seizures from 100 children < or =12 years old was performed. All patients had a history of therapy-resistant partial epilepsy and a seizure-free postoperative outcome. The presence and attributes of IP were analyzed. RESULTS: No IP was detected by reviewing the archived seizures. According to medical charts, IP was reported in 11/100 children (six girls) aged 14 months to 12 (mean 5.5+/-4.1) years. Ten of them had temporal lobe epilepsy (p=0.046) - including nine temporo-medial and one temporo-lateral cases - while only one child had an extratemporal (parietal lobe) seizure onset zone. All but one children had left-sided operation (p=0.01). Presence of IP had a positive predictive value of 91% for both lateralizing (left) and localizing (temporal lobe) the seizure onset zone. History of IP was neither age-, epilepsy onset-, nor gender-related. CONCLUSIONS: Ictal pallor is a frequently reported autonomic symptom during childhood focal seizures but difficult to assess purely by video-monitoring. It has a high predictive value to localize the seizure onset zone to the left temporal region already in very young patients.     

Heart rate increase in otherwise subclinical seizures is different in temporal versus extratemporal seizure onset: support for temporal lobe autonomic influence.

Ictal heart rate was investigated in otherwise subclinical epileptic seizures to test the hypothesis as to whether ictal tachycardia is physiological and not a physical or psychological stress response. In addition, we aimed to evaluate the localizing significance of pure ictal tachycardia. We included 21 epilepsy patients, who showed an ictal EEG seizure pattern during 22, otherwise subclinical seizures. All patients underwent ictal video-EEG recordings to evaluate the possibility of resective epilepsy surgery. The changes in heart rate in these patients were investigated in order to determine their relationship to localization and duration of EEG seizure patterns. Ictal tachycardia was observed in 41% of the otherwise subclinical seizures (nine out of 22), and significantly more often in seizures arising from the temporal lobe than from extratemporal regions (62% versus 11%, p < 0.0018). The seizure duration as defined by EEG was significantly positively correlated with an increase of heart rate (p = 0.043). Ictal heart rate can increase as a result of epileptic activation of autonomic cortex, reflecting a temporal lobe autonomic influence. Thus, measurement of heart rate should be included in the evaluation of otherwise subclinical epileptic seizures, because of its localizing value.     

Localization of seizure foci: pitfalls and caveats.

The pitfalls and difficulties in accurately localizing seizure foci are reviewed. Basic issues regarding modeling, volume conduction, inhomogeneities, and corticocortical propagation are discussed, and the limitations of scalp and intracranial recordings are outlined. The ambiguities in interpreting patterns and their significance are highlighted with a concluding commentary on pitfalls in defining the epileptogenic region.     

Ictal hiccup during absence seizure in a child.

Absence seizures are one of the features of idiopathic generalised epilepsy (IGE) and occur as component of many different syndromes. They are commonly associated with various clinical features such as mild clonic components, change in postural tone, automatisms and autonomic phenomena. Childhood absence epilepsy (CAE) is the prototype IGE with typical absence seizures. We report a child who had prominent ictal hiccups during an absence seizure, and discuss the possible mechanisms. [Published with video sequences].     

Ictal EEG wave forms from epidural electrodes predictive of seizure control after temporal lobectomy

Ictal wave form characteristics — frequency, spatial distribution, and duration — were analyzed for 140 complex partial seizures recorded from epidural strip electrodes implanted in 28 patients. None had abnormalities on imaging studies. All had bilateral electrode placements, unilateral seizure onsets, temporal lobectomies, and were followed for a mean of 33 months postoperatively. Sixteen patients (57%) became free of complex partial seizures: 12 had reductions in seizure frequency of a least 50% but were not seizure-free.The only predictor of the seizure-free state was the presence of low voltage fast activity (LVF), in the alpha or beta ranges, localized to one gyrus. This phenomenon occurred in 14/16 seizure-free patients, 2/12 of others (P < 0.001). As seizures progressed, LVF typically increased in amplitude, propagated, and slowed into the theta range.Wave forms were classified into 8 categories based upon their frequency and morphology. Stepwise discriminant analysis of these wave forms, with consideration of whether they were localized or regional, revealed that both frequency and localization were critical for the post-surgical prognosis. The mere presence of a localized seizure onset was unreliable unless the wave form was taken into account.Well-localized rhythmic activity over 8 Hz at seizure onset from epidural subtemporal electrodes predicts surgical success. Slower rhythms imply greater separation in space and time from seizure onset.     

Ictal semiology in patients with medial temporal lobe epilepsy: value in lateralizing the seizure focus]

We have evaluated useful lateralizing signs in 28 patients with medial temporal lobe epilepsy who were seizure-free after anterior temporal lobectomy by reviewing videotapes during video-EEG monitoring. The most frequent types of aura were epigastric sensation and psychic symptom in 8, respectively, both of which did not predict lateralization of the focus. Of the motor signs, early head deviation and unilateral upper extremity automatism predicted an ipsilateral focus in 72 and 80%, respectively. On the other hand, late head deviation(< 15 seconds before secondarily generalized seizure) and unilateral upper extremity dystonic posturing predicted a contralateral focus in 80 and 100%, respectively. Twelve of the patients displayed oroalimentary automatism which did not predict focus lateralization. Three patients with ictal speech demonstrated a seizure focus contralateral to their language-dominant hemisphere. In medial temporal lobe epilepsy, several clinical seizure manifestations such as: early and late head deviation, unilateral upper extremity automatism and dystonic posturing were not a little noted and provided additional information as to the side of seizure origin.     

Medial temporal lobe neuronal damage in temporal and extratemporal lesional epilepsy

OBJECTIVE: To assess the extent of medial temporal lobe (TL) abnormalities of the neuronal marker N-acetylaspartate (NAA) in TL and extra-TL lesional partial epilepsy, and to determine whether decreases in NAA are related to lesion location, to lesion pathology, or to the seizures themselves. METHODS: The authors studied 19 patients with intractable partial epilepsy and an isolated structural cerebral lesion (10 TL, 9 extra-TL; 10 cortical dysplasia [CD], 9 non-CD lesions). Proton MRS imaging was used to determine the average relative resonance intensity of NAA for the TL regions of the left and right hemispheres. Values less than two SDs below the mean of normal control subjects were considered abnormal. RESULTS: Fourteen patients (74%) had abnormally low NAA relative to creatine (NAA/Cr) in at least one TL. Three-way analysis of variance (ANOVA; lesion pathology, lesion location, side of NAA/Cr decrease) showed that ipsilateral NAA/Cr was lower than contralateral (p = 0. 04). Three-way ANOVA (lesion location, generalized tonic-clonic seizures, side of NAA/Cr decrease) showed that generalized tonic-clonic seizures were associated with lower TL NAA/Cr (p = 0. 02). Lesion location and pathology showed no main effect on the NAA-to-Cr ratio in either analysis (p > 0.05). Linear regression analyses between seizure duration and NAA/Cr decrease was not significant. CONCLUSION: The authors demonstrated abnormally low TL NAA/Cr in the majority of patients with structural cerebral lesions. This abnormality did not differ with lesion location or pathology. They propose that the altered function of neuronal networks by an isolated structural cerebral lesion results in remote "functional dual pathology."     

Chronic epileptic foci in monkeys: correlation between seizure frequency and proportion of pacemaker epileptic neurons.

A total of 1,802 neurons from 15 alert, undrugged Macaca mulatta monkeys were studied. Thirteen monkeys had chronic epilepsy induced by subpial alumina injections in precentral cortex. Precentral neurons were judged epileptic by the magnitude and variability of the percentage of interspike intervals less than 5 msec during periods when the monkeys were awake. This method of quantifying epileptic single neuron activity appears highly reliable in distinguishing epileptic neurons from precentral neurons in either normal cortex, cortex contralateral to, or within the focus. For the 13 epileptic monkeys, the relative proportion of strongly epileptic neurons found within foci was logarithmically correlated with the mean number of daily seizures. Because of the similarity between the physiology of the alumina focus in monkeys and epileptic foci in humans, these data imply that the severity of focal human epilepsy is a function of epileptic neuronal mass.     

Localization of extratemporal epileptic foci during ictal single photon emission computed tomography.

We obtained single photon emission computed tomography (SPECT) scans with technetium-99M-hexamethyl-propylene-amine-oxime in 11 patients during 12 extratemporal partial seizures (9 simple partial, 3 complex partial). Ten ictal SPECT studies in 9 patients showed a focal region of hyperperfusion, which agreed with electrical seizure onset in 5 and with clinical seizure localization in 4 in whom ictal electroencephalography was not localized. Contralateral cerebellar and ipsilateral basal ganglia hyperperfusion was seen in 3 patients with a frontal lobe seizure focus. Ictal hyperperfusion was well circumscribed, unlike the diffuse hyperperfusion changes reported during temporal lobe seizures. This observation may indicate a different degree of seizure spread in temporal as opposed to extratemporal epilepsy. Because electroencephalographic localization is often elusive in extratemporal seizures, ictal SPECT may be very helpful for the localization of extratemporal foci.     

颞叶癫痫致痫灶的定位方法评价

探讨目的：用不同的方法对癫痫灶定位的评估。病程１２１．２个月,进行回顾。方法：利用症状学,神经心理学,头皮／蝶骨嵴脑电皮层脑电图,深部脑电图,ＣＴ,ＭＲＩ七种方法在４０例难治性颞叶癫痫中的应用,其中１３例患者定位的准确性通过手术后一年以上疗效的随访得到证实。结果：２１／４０例由症状学表现得到诊断,９／２７例由神经心理学测试定侧。头皮脑电图、皮层脑电图及深部脑电图的定位率分别为３０／４０、３０／３７和２９／３５。ＣＴ与ＭＲＩ的定位率分别为１２／２５和３２／４０。各种定位方法的准确性有显著差异,其中神经心理学的定位能力明显低于常规脑电图、ＭＲＩ、皮层脑电图和深部脑电图。结论：总结了各种定位方法的优劣势,指出准确的定位需要功能性定位与结构性定位方法的综合应用。最具价值的仍是侵袭性电极的检查,神经心理学的定位价值较小     

颞叶癫痫致痫灶定位方法准确性临床研究

目的探讨颞叶癫痫致痫灶综合定位方法的准确性,总结出简便准确的综合定位程序。方法回顾性分析60例手术治疗的难治性颞叶癫痫患者资料,分析归纳所采用的不同致痫灶综合定位方法,并以此将病例分为5组：A组为磁共振（MRI）阳性＋视频脑电图（VEEG）＋皮层及深部电极（ECoG及DEEG）组,B组为MRI阳性＋VEEG＋单光子发射计算机断层成像（SPECT）＋ECoG及DEEG组,C组为MRI阳性＋VEEG＋正电子发射计算机断层显像-计算机体层扫描（PET-CT）＋ECoG及DEEG组,D组为MRI阴性＋VEEG＋SPECT＋ECoG及DEEG组,E组为MRI阴性＋VEEG＋PET-CT＋ECoG及DEEG组。所有病例均获随访,按Engel分级进行术后疗效评估,以Ⅰ～Ⅲ级作为效果良好的评价标准,并作为致痫灶定位准确的标准,通过统计学分析,计算出各种方法的定位准确率,对不同综合定位程序的定位能力做出评价。结果致痫灶准确定位病例A组16例（16/18）,B组10例（10/11）,C组16例（16/17）,D组3例（3/4）,E组8例（8/10）;A、B、C三组间定位能力无显著差异,D、E组明显低于A、B、C三组,D组定位能力最差。结论 MRI结果阳性且与VEEG一致者可定位致痫灶;MRI阴性而VEEG与PET-CT结果一致者可定位致痫灶;术中皮层及深部电极监测是致痫灶再定位及指导手术的标准。