Correlation Between Interictal Regional Cerebral Blood Flow and Depth-Recorded Interictal Spiking in Temporal Lobe Epilepsy

Summary: Purpose: Single photon emission computed tomography (SPECT) is used as an adjunctive method in preoperative localization of epileptic foci. In temporal lobe epilepsy (TLE), interictal hypoperfusion is observed in 60–70% of cases. Correlation with ictal EEG changes is observed in ～50–60% of cases. Relationships with interictal EEG have been studied less. We compared interictal SPECT data obtained in 20 patients with their interictal intracerebral electrical activity recorded by depth electrodes to evaluate a potential relationship. Methods: We studied 20 sequential patients whose clinical, surface, and depth EEG data indicated seizure originating in the temporal lobe and who had interictal [^99mTc]hexamethyl-propylene amine oxime (HMPAO)-SPECT stereo-EEG (SEEG). Intracerebral electrodes were placed according to the patient's profile. The interictal extent of epileptiform activity allowed delineation of the irritative zone. Interictal spike frequency was also analyzed semiquantitatively. Visual and numerical SPECT analysis was performed blind to SEEG data. Results: Interictal hypoperfusion was observed in 16 patients, involving the epileptogenic temporal lobe in 14. Except for 1 patient who manifested lateral temporal hypoperfusion corresponding to a mass lesion, two distinctive patterns of hypoperfusion were noted: (a) mesial hypoperfusion (5 patients), and (b) global temporal hypoperfusion (8 patients). In 8 patients, hypoperfusion had also extended into the adjacent cortex. Temporal mesial hypoperfusion was associated with spiking limited to the mesial structures, whereas global temporal hypoperfusion or hypoperfusion extending beyond the temporal lobe was associated with a similar topographic pattern of spikes. Conclusions: Comparison between SPECT and SEEG data collected in the interictal phase indicated that the extent of the hypoperfused area correlated topographically with that of the underlying irritative zone.     

High Signal Intensity on T2- Weighted MRI Correlates with Hypoperfusion in Temporal Lobe Epilepsy

Single-photon emission computed tomography (SPECT) and [99mTc]HMPAO were used to assess the functional significance of nonspecific magnetic resonance imaging (MRI) abnormalities observed in patients with temporal lobe epilepsy and no focal lesion on CT scan. We studied 18 patients whose MRI was normal or showed high signal intensity on T2-weighted images (T2WIs) at the site of the EEG focus in 11 and 7 cases, respectively. EEG was monitored during regional cerebral blood flow (rCBF) study. Lateralized hypoperfusion was present in 7 of 17 interictal (41%) and in one postictal cases; it was located in the temporal lobe on the side of the EEG focus in all, and was significantly more frequent in patients with high signal intensity on T2WI (86%) than in patients with a normal MRI (18%). The degree of temporal perfusion asymmetry measured in each individual was higher in patients whose MRI was abnormal.     

Interictal “patchy” regional cerebral blood flow patterns in migraine patients. A single photon emission computerized tomographic study

In 92 migraine patients and 44 healthy control subjects we recorded regional cerebral blood flow (rCBF) with single photon emission computerized tomography and ¹³³Xe inhalation or with i.v. ^99mTc-HMPAO. Migraine patients were studied interictally. A quantitated analysis of right-left asymmetry indices in a fixed set of regions of interest was compared with the normal asymmetry indices in the healthy controls. An asymmetry index deviating more than ± 2.5 S.D.s in normals was defined as pathological asymmetry. By quantitated analysis 47% of images from patients with aura attacks and 48% of images from patients without aura attacks were established to contain higher rate of asymmetries, the difference being statistically significant (p < 0.05, Wilcoxon). A blinded visual analysis and scoring by a four level scale were done by four experienced observers. rCBF images from 18% of patients having attacks with aura and from 19% of patients without aura attacks was scored as containing abnormal right-left asymmetries by the visual analysis. Images from healthy controls were all scored to be normal. In 37% of the images (all from patients) there was lack of consensus among observers (κ = 0.28). There was no correlation between visual or quantitated abnormalities and age, duration of migraine, frequency of attacks or prophylactic medication. No correlation could be established between asymmetries and the usual side of headache or aura symptoms. Two conclusions emerged: (1) visual evaluation of interictal migraine rCBF images is insufficient to pick up abnormalities; (2) almost 50% of the migraine sufferers had abnormal rCBF/asymmetries. However, these are discrete compared with those typically seen during the aura phase of a migraine attack. One explanation to the patchy rCBF patterns might be that they reflect interictal cerebrovascular dysregulation which might to be a common feature in both types of migraine.     

Usefulness of Ictal and Interictal 99mTC Ethyl Cysteinate Dimer Single Photon Emission Computed Tomography in Patients with Refractory Partial Epilepsy

Summary: Purpose: Ictal perfusion single photon emission computed tomography (SPECT), using HMPAO, has been shown to localize epileptic foci in ～90% of studies. Unfortunately, HMPAO decomposes rapidly, precluding the performance of ictal studies. Ethyl cysteinate dimer (ECD) is a SPECT perfusion agent recently approved by the Food and Drug Administration. After preparation, this compound is stable for ～6 h. facilitating the performance of ictal studies. Methods: In a prospective, open-label, uncontrolled, non randomized study, we evaluated the potential benefits of the use of ^99mTc-ECD SPECT for lateralization of the epileptic focus. Ten consecutive adult epilepsy surgery candidates were studied with ictal and interictal ^99mTc-ECD SPECT. Results: The mean delay between seizure onset and ictal SPECT injection was 23.2 s. The mean seizure duration was 84.1 s. Ictal studies agreement between the epilepsy focus and area of hyperperfusion was evident in 8 of 10 cases. In one case, SPECT was lateralized in a patient with bilateral temporal lobe epilepsy (TLE); however, hyperperfusion was observed on the same side of that particular seizure. In another case, there was location disagreement. Interictal SPECT showed focal hypoperfusion in three cases. Conclusions: ^99mTc-ECD proved to be an optimal tracer for ictal studies. Although this is a small series, the results of ictal and interictal findings using 99mTc-ECD are similar to those reported with ^99mTc-HMPA0. Because ^99mTc-ECD has a longer decomposition time, true ictal studies are easier to obtain. This new tracer will probably allow the use of ictal SPECT to become widely accepted in most epilepsy centers.     

长期应用抗癫癎药控制的颞叶癫癎患者发作间期SPECT异常灌注灶修复与长程视频脑电图变化的临床研究

目的：探讨抗癫癎药（AEDs）长期控制的颞叶癫癎患者发作期间应用单光子发射电子计算机断层扫描（SPECT）检查异常灌注灶的修复。方法：颞叶癫癎患者经AEDs、步长脑心通胶囊与尼莫地平治疗,并在两次发作间期行SPECT、长程视频脑电图（V-EEG）和CT/MRI检查。结果：44例癫癎患者平均年龄为25岁;平均病程为3.5年;44例患者中病因明确者为19例（家族史2例,围产期损伤1例,热性惊厥3例,颅脑损伤出血1例,颅脑外伤5例,脑膜脑炎3例,脑部手术2例,多病因2例）。癫癎发作控制平均为25个月。治疗前发作间期SPECT异常（颞叶和非颞叶）感兴趣区（ROI）为77.3%,长程V-EEG异常77.3%（其中癎样放电88.2%）,治疗前CT/MRI异常47.7%。治疗后发作间期SPECT正常增加4.5%（P〉0.05）,异常灶减少8.3%（P〉0.05）;长程V-EEG正常增加27.3%（P〈0.05）,癎样放电减少53.3%（P〈0.05）;结论：长期控制的颞叶癫癎患者的异常灌注灶修复明显低于其他类型癫癎,防治重点应放在颞叶癫癎症状出现之前的继发性全身强直阵挛发作。     

放射性核素局部脑血流断层显像在儿童癫癇中的应用

目的 :探讨放射性核素局部脑血流 (rCBF)断层显像在儿童癫中临床应用的价值。方法 :2 0 8例癫患儿行rCBF显像 ,并与EEG、CT及MRI对照。结果 :SPECTrCBF显像、EEG、CT及MRI对儿童癫病灶的检出率分别为 67 7%、81 6%、2 2 0 %及 2 5 4% ,rCBF显像定位比EEG精确 ,癫病灶多见于顶、颞及基底节。结论 :rCBF断层显像可为临床准确诊断癫及癫定位提供依据     

Diagnosis of Temporal Lobe Epilepsy by Positron Emission Tomography

Abstract. Temporal lobe epilepsy was studied by the ¹¹C-glucose method of positron emission tomography. The temporal lobe at the level 25 mm above the orbitomeatal line showed the amygdala, hippocampus and hippocampal gyrus medially, and the T1, T2 and T3 neocortices laterally. The focus locations in these structures were divided into mesial, lateral and combined groups on the PECT images. This classification showed a close correlation between the clinical symptoms and the anatomical focus sites.     

Ictal Single Photon Emission Computed Tomography in Occipital Lobe Seizures

Summary: Purpose: Ictal single photon emission computed tomography (SPECT) has been evaluated as an adjunctive localizing technique in temporal lobe epilepsies and, to a lesser degree, in some extratemporal epilepsies. The purpose of this study was to determine whether occipital lobe seizures are associated with distinctive ictal cerebral blood perfusion (rCP) patterns.
Methods : SPECT was used with the tracer ^99mTc HMPAO to image ictal rCP in 6 patients in whom clinical, EEG, and imaging data indicated occipital lobe seizures.
Results : Two patterns of rCP were seen. Four patients had hyperperfusion that was restricted to the occipital lobe, and two patients had hyperperfusion of the occipital lobe and the ipsilateral mesial temporal lobe, with hypoperfusion of the lateral temporal lobe. The latter 2 patients had clinical and surface EEG evidence of temporal lobe involvement in the seizure discharge.
Conclusions : Ictal rCP patterns in occipital lobe seizures are distinct from those in temporal lobe seizures and may vary according to whether or not ipsilateral temporal lobe structures are involved in the ictal discharge.     

Interictal Spikes and Hippocampal Somatostatin Levels in Temporal Lobe Epilepsy

We investigated the relationship between somatostatin-like immunoreactivity (SSLI) and interictal spikes (IIS) in human temporal lobe epileptic tissue. IIS counted manually from depth electrode recordings obtained preoperatively were expressed as spike frequency in anterior, middle, and posterior portions of hippocampus. SSLI was determined by radioimmunoassay (RIA). An inverse relationship between SSLI in the entorhinal cortex (EC) and IIS frequency in hippocampus was present (r = -0.55, p = 0.06). No correlation between IIS and SSLI in CA4, CA3, CA1, or the dentate was evident. This finding suggests a role of the EC in generation, regulation, or expression of interictal paroxysmal electrical activity in temporal lobe epilepsy (TLE), for which somatostatin may be a marker.     

Interictal Spiking Increases with Sleep Depth in Temporal Lobe Epilepsy

Summary: Purpose : To test the hypothesis that deepening sleep activates focal interictal epileptiform discharges (IEDs), we performed EEG-polysomnography in 21 subjects with medically refractory temporal lobe epilepsy.
Methods: At the time of study, subjects were seizure-free for 224 h and were taking stable doses of antiepileptic medications (AEDs). Sleep depth was measured by log delta power (LDP). Visual sleep scoring and visual detection of IEDs also were performed. Logistic-regression analyses of IED occurrence in relation to LDP were carried out for two groups of subjects, nine with frequent IEDs (group 1) and 12 with rare IEDs (group 2).
Results: The LDP differentiated visually scored non-rapid eye movement (NREM) sleep stages (p = 0.0001). The IEDs were most frequent in NREM stages 3/4 and least frequent in REM sleep. Within NREM sleep, in both groups, IEDs were more frequent at higher levels of LDP (p < 0.05). In group 1, after accounting for the level of LDP, IEDs were more frequent (a) on the ascending limb of LDP and with more rapid increases in LDP (p = 0.007), (b) in NREM than in REM sleep (p = 0.002), and (c) closer to sleep onset (p < 0.0001). Fewer than 1% of IEDs occurred within 10 s of an EEG arousal.
Conclusions: Processes underlying the deepening of NREM sleep, including progressive hyperpolarization in thalamocortical projection neurons, may contribute to IED activation in partial epilepsy. Time from sleep onset and NREM versus REM sleep also influence IED occurrence.     

Neuroimaging in Temporal Lobe Epilepsy: Test Sensitivity and Relationships to Pathology and Postoperative Outcome

We studied patients with documented temporal lobe seizures to evaluate the predictive value of computed tomography (CT), magnetic resonance imaging (MRI), and F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for surgical therapy and the relationships between these tests and the pathologic diagnoses. CT detected abnormalities in 32.5%, with an accuracy of 19% when accuracy was defined as congruence with electrophysiologic studies. MRI detected abnormalities in 81%, with an accuracy of 67%. FDG-PET detected abnormalities in 85%, with an accuracy of 82%. Pathologic change was detected in 79% of the excised temporal neocortex, 65% of amygdalae, and 93% of hippocampi. After follow-up periods of 20-71 months (mean 41 months), 67% of patients were free of seizures and 94% had at least a 90% reduction in seizure frequency. There was no relationship between the type of abnormality on MRI or the type of pathology and postoperative outcome. Better outcomes were associated with focal or regional ictal onsets as recorded by surface EEG. Worse outcomes were associated with hypometabolism that extended outside the temporal lobe. Pathologic change in the temporal neocortex was associated with extension of hypometabolism outside the temporal lobe.     

强迫症与抑郁症的脑单光子发射计算机断层扫描对照研究

目的探讨强迫症、抑郁症局部脑血流量(rCBF)特点。方法应用单光子发射计算机断层扫描(SPECT)技术,对首发且未经治疗的39例强迫症患者、36例抑郁症患者和39名正常人于静息状态下行脑血流显像。以小脑皮质的放射性计数值为参考,对局部脑血流进行半定量分析。结果强迫症组两侧前额叶、前颞叶rCBF高于正常组(P<0.01);抑郁症组两侧前额叶、枕叶、扣带回及右前颞叶、右顶叶rCBF低于正常组(P<0.05);在两侧前额叶、前颞叶、顶叶、枕叶及右后额叶、扣带回,强迫症组rCBF高于抑郁症组(P<0.05)。结论强迫症组的前额叶及前颞叶呈高灌注改变,抑郁症组脑血流普遍低灌注,SPECT技术可望作为二者鉴别诊断的客观依据之一。     

Prognostic Significance of Ictal and Interictal Epileptiform Activity in Temporal Lobe Epilepsy

Summary: Long-term electrocorticograms (ECoG), recorded by chronically implanted subdural electrodes during preoperative evaluation of 59 patients with temporal lobe epilepsy (TLE) were analyzed retrospectively to assess the prognostic relevance of distribution of interictal epileptiform potentials (IEP) and seizure origin (SO) and to investigate factors affecting their lateralization. Subsequent to preoperative evaluation, a standardized two thirds anterotemporal lobectomy including subtotal hippocampectomy had been performed in all patients. The following results were obtained: (a) Only patients with 100% lateralization of SO and IEP had excellent seizure outcome (= 89% seizure-free); (b) patients with bitemporal SO were unlikely to benefit from surgical treatment (=12.5% seizure-free); (c) 40–56% patients with unilateral temporal SO and bitemporal IEP, became seizure-free irrespective of the degree of lateralization of IEP; and (d) multidimensional analysis of variance showed that lateralization of SO, presence of a magnetic resonance imaging (MRI)-detectable lesion, presence of hippocampal sclerosis, presence of febrile seizures and seizures at age ≥6 years are the five most important variables indicating abolition of seizures. Combined analysis of ECoG-recorded SO and IEP allows prediction of postoperative seizure control within close boundaries.     

SPECT findings during postictal psychoses: predominance of relative increase of perfusion in right temporal lobe

To identify brain regions activated during episodes of postictal psychoses (PIP), we investigated single-photon emission computed tomography (SPECT) data obtained from five patients treated at our institutions and also reviewed four previous studies. Therefore, SPECT findings in a total of 19 cases were analyzed, including 16 patients with temporal lobe epilepsy (TLE). During nonpsychotic states, the laterality of epileptic foci was judged as left-sided in nine episodes, right-sided in six episodes, and nonlateralized in four episodes. In PIP states, 88% of the patients showed a relative increase of right temporal perfusion (increased right temporal or decreased left temporal perfusion). Regardless of whether right- or left-sided pathology was suspected during a nonpsychotic state, SPECT findings obtained during PIP episodes revealed a trend of right-sided temporal predominance.     

Temporal Lobe Epilepsy in Children: Electroclinical Study of 77 Cases

Summary:  Purpose: Temporal lobe epilepsy (TLE) is probably more difficult to recognize in children than in adults. In fact, ictal symptoms in children are less stereotyped and less obvious, and the neuropathological substrate is more heterogeneous than in adults. The aim of this study is to examine the relationships between etiology, age at onset and electroclinical findings in 77 children with TLE, 32 of whom were surgically treated.
Methods: Electroclinical study including video-EEG recording of seizures in 77 children with TLE. The investigation focused on the first five initial ictal symptoms.
Results: Age at onset was less than 3 years in 39 cases, between 3 and 6 years in 17 cases and older than 6 years in 21 cases. Auras also occurred in younger children but were more common after the age of 6 years. A peculiar initial ictal semiology consisted in staring with arrest, lip cyanosis, and very slight oral automatisms. In some cases, EEG recordings documented seizures starting independently on both temporal lobes. Based on electroclinical and neuroradiological features, we recognized three subgroups: symptomatic TLE due to cortical malformations or nonevolutive tumors, TLE with mesial temporal sclerosis, and cryptogenic TLE.
Conclusions: A correct electroclinical and neuroradiological approach allows in several cases early recognition of TLE even when onset is earlier than the age of 6 years. A correct definition of the localization relies primarily on video-EEG recording of the seizures, possibly repeated during follow up in cases lacking obvious neuroradiological correlation.     

Interictal Epileptiform Discharges in Temporal Lobe Epilepsy Due to Hippocampal Sclerosis Versus Medial Temporal Lobe Tumors

PURPOSE: It remains controversial whether a specific pattern of interictal epileptiform activity exists that may help to differentiate temporal lobe epilepsy (TLE) due to hippocampal sclerosis (HS) from other forms of TLE. In this study, we characterized the distribution of interictal epileptiform discharges in TLE due to HS as compared with those in patients with tumors restricted to the medial temporal lobe structures. METHODS: The study included 21 adult patients with unilateral HS who remained seizure free (>1 year) after anterior temporal lobectomy with amygdalohippocampectomy. Patients with "dual pathology" were excluded. The comparison group consisted of nine patients with tumors restricted to the amygdala and hippocampus. All patients underwent video-EEG monitoring preoperatively by using 39 scalp electrodes (including the 10-10 system over both temporal regions) and bilateral sphenoidal electrodes. RESULTS: The HS patient group showed a significantly higher percentage of ipsilateral epileptiform discharges maximal at anterior temporal electrodes (median, 97.0%; sphenoidal electrode alone, 88.1%), as compared with the tumor group (median, 72.1%; p<0.001; sphenoidal electrode alone, 24.8%; p<0.001). The HS group had significantly fewer extratemporal spikes/sharp waves (median, 0.0), as compared with the tumor group (10.0%; p<0.001). At least 90% of the interictal discharges were located in the anterior temporal region in 20 (95.2%) of 21 HS patients, but in none of the tumor patients (p<0.001). Bilateral temporal discharges were found in nine (42.9%) of 21 patients with HS and in two (22.2%) of nine tumor patients (p = 0.42). CONCLUSIONS: We conclude that ipsilateral interictal epileptiform discharges outside the anterior temporal region are rare (<10%) in adults with intractable TLE due to unilateral HS. Frequent posterior or extratemporal sharp waves may detract from the certainty of this diagnosis in complicated cases. These restricted epileptiform discharges suggest a smaller irritative zone in HS as compared with medial tumors, or a more organized activity associated with intrinsic hippocampal disease. Bilateral epileptiform discharges were not uncommon in both groups.     

Cerebellar Hypometabolism in Focal Epilepsy Is Related to Age of Onset and Drug Intoxication

Summary: Purpose: We wished to investigate the cerebellar depression of regional cerebral glucose metabolism (rCMRGlu) in patients with focal epilepsy.
Method: In 170 consecutive patients with medically refractory, focal epilepsy the rCMRGlu was measured in cerebellum and brain.
Results: rCMRGlu was markedly decreased in both cerebellar hemispheres and slightly in brain. The cerebellum to brain rCMRGlu ratio was significantly decreased in patients with seizure manifestation in infancy, but was normal due to a progressive decrease in brain rCMRGlu in later age. A subgroup of patients with focal epilepsy involving the frontal lobe had a reduced cerebellum/brain rCMRGlu ratio, whereas in patients with mesiotemporal lobe epilepsy (MTLE), the rCMRGlu was decreased to the same degree in cerebellum and brain. The difference in the cerebellum/brain rCMRGlu ratio between the two groups was accounted for by the younger age of the patients with focal epilepsy involving the frontal lobe, however. In another subgroup of patients with a documented history of critical drug intoxications, the cerebellar rCMRGlu was severely decreased, resulting in a significantly reduced cerebellum/brain rCMRGlu ratio.
Conclusion: Our retrospective study suggests that the cerebellum is particularly vulnerable in infancy to ongoing epileptic activity and high dosage of antiepileptic drugs (AEDs).     

癫痫手术前SPECT的定位价值

目的：了解单光子发射计算机断层扫描（ＳＰＥＣＴ）行局部脑血流检查在致痫灶定位中的应用价值。方法：对２４例癫痫患者行ＳＰＥＣＴ检查，结果采用目测和半定量分析两种方法进行判断。结果：１３／２４（５６％）的患者有目测的异常灌注区，其中１１／１３（８５％）与综合定位的结果相一致，半定量分析的方法可发现１２／１２的患者有异常灌注区，其中１０／１２（８３％）可得到与综合定位结果相一致的结论。统计学显示两种方法在阳性检出率和准确率上有显著差异。结论：ＳＰＥＣＴ在致痫灶的定位中有较高的应用价值，半定量分析的方法可明显提高ＳＰＥＣＴ对致痫灶的检出率，但应将检查结果与临床及其他检查资料相结合进行分析以减少假阳性率     

Does regional brain perfusion correlate with eating disorder symptoms in anorexia and bulimia nervosa patients?

OBJECTIVE: Using single photon emission computed tomography (SPECT), we sought brain perfusion correlates of eating disorder symptoms in anorexia and bulimia nervosa patients. METHOD: We investigated 67 female eating disordered (ED) patients. Eating disorder symptoms were measured by the Eating Disorders Inventory (EDI). Determination of brain areas in which regional perfusion co-varied with drive for thinness, bulimia, body dissatisfaction, ineffectiveness, perfectionism, interpersonal distrust, interoceptive awareness and maturity fears was done by open explorative correlation analysis using Statistical Parametrical Mapping (SPM). RESULTS: A significant positive correlation between scores on body dissatisfaction and ineffectiveness, and brain perfusion in the prefrontal and parietal cortex was demonstrated. There were no correlations between other eating disorder symptoms and brain perfusion. CONCLUSION: Based on the finding of an association between regional brain flow and body dissatisfaction and ineffectiveness, we argue that neurobiological findings in ED patients may not only reflect emotional and behavioural factors but cognitive-evaluative features as well.