Preictal SPECT in temporal lobe epilepsy: regional cerebral blood flow is increased prior to electroencephalography-seizure onset

Peri-ictal SPECT provides unique information on the dynamic changes in regional cerebral blood flow (rCBF) that occur during seizure evolution and, thus, could be useful in clarifying the poorly understood interplay of the interictal and ictal states in human focal epilepsy. The regional hyperperfusion observed on ictal SPECT is generally believed to be a consequence of electrical seizure activity. However, recent studies using invasive long-term cortical CBF monitoring have demonstrated that rCBF changes occur up to 20 min prior to ictal electroencephalography (EEG) onset. Because of apparent technical difficulties, no preictal SPECT studies have been reported so far. Therefore, we present our results on two patients with temporal lobe epilepsy in whom preictal SPECT scans were performed fortuitously under continuous video-EEG monitoring control. METHODS: Technetium-99m-hexamethyl propyleneamine oxime was injected 11 min (Patient 1) and 12 min (Patient 2) before clinical and EEG seizure onset, as documented from simultaneous video-EEG monitoring in two patients with temporal lobe epilepsy. We obtained accurate anatomical reference of CBF changes visible on SPECT by a special coregistration technique of MRI and SPECT. RESULTS: Whereas interictal SPECT showed a hypoperfusion of the temporal lobe ipsilateral to the seizure focus, on preictal SPECT, a significant increase in rCBF in the epileptic temporal lobe could be observed. These rCBF changes were not accompanied by any significant changes of the ongoing EEG. CONCLUSION: Our study provides evidence that rCBF is increased in the epileptic temporal lobe several minutes before EEG seizure onset. Thus, rCBF changes observed on peri-ictal SPECT scan cannot be considered a mere consequence of EEG seizure activity but may rather reflect a change in neuronal activity precipitating the transition from the interictal to the ictal state.     

Ictal and interictal technetium-99m-bicisate brain SPECT in children with refractory epilepsy

Identification of epileptogenic foci in patients with refractory epilepsy remains a significant diagnostic challenge. Magnetic resonance imaging studies frequently fail to reveal an anatomic origin for the seizures, and scalp electroencephalography is often limited to identification of the involved hemisphere. Functional imaging modalities such as PET and SPECT are more promising tools for this application because they reflect the functional pathology associated with the seizure. These changes are more pronounced ictally, but until recently, no radiopharmaceutical was available that could be used routinely for ictal SPECT. The present study was therefore undertaken to determine whether 99mTc-bicisate could be used in ictal SPECT in pediatric patients with refractory epilepsy, to compare the patterns of ictal and interictal blood flow in these patients and to compare the localization information provided by ictal SPECT with that available from other techniques. METHODS: Technetium-99m-bicisate/SPECT was compared prospectively with scalp EEG for its ability to identify a possible seizure focus in pediatric patients with refractory epilepsy. Ictal and interictal SPECT studies were performed in 10 patients (3-19 yr old, mean age 10.9 +/- 4.3 yr; 7 female, 3 male) in whom MRI scans revealed no lesions that might be responsible for the seizures. RESULTS: Ictal SPECT was performed in all patients, and all ictal studies revealed focal perfusion abnormalities. By comparison, four of the interictal SPECT studies showed regional hypoperfusion that corresponded to the regions of hyperperfusion in the ictal studies, and three showed regional hyperperfusion corresponding to the hyperperfused regions in the ictal studies. Three interictal studies revealed no abnormal perfusion. Scalp EEG provided localization information in five patients. CONCLUSION: These initial results suggest that ictal SPECT with 99mTc-bicisate is a more promising tool for the identification of epileptogenic foci than interictal SPECT or scalp EEG in patients without focal abnormalities on MRI.     

Magnetic source imaging of abnormal low-frequency magnetic activity in presurgical evaluations of epilepsy

PURPOSE: Regional cortical dysfunction associated with epileptogenic activity was predicted from interictal localized abnormal low frequency neuromagnetic activity (ALFMA) using Magnetic Source Imaging (MSI). ALFMA can be detected in patients who show no interictal spikes. METHODS: A large array biomagnetometer was used in a blinded, rapid screening protocol. The MSI procedure required no alteration in epileptic medications. MSI results were compared with the presumed epileptogenic region as determined by a consensus of standard techniques, which included MR and electroclinical monitoring. RESULTS: One or more sites of localized abnormality were detected by MSI ALFMA in 29 of the 33 epileptic patients. ALFMA mapped with MSI showed a 48.5% specificity with respect to the presumed epileptogenic region. MSI ALFMA was in agreement with the final consensus as often as was ictal noninvasive video EEG monitoring, and was exceeded in specificity overall only by invasive ictal video EEG monitoring, which was required for conventional localization in 21 of the 33 patients tested with MSI. CONCLUSIONS: ALFMA measurements with MSI may augment the array of noninvasive methods used for reaching a consensus for epilepsy surgery.     

Neuron loss localizes human temporal lobe epilepsy by in vivo proton magnetic resonance spectroscopic imaging

Temporal lobe epileptogenic foci were blindly localized in 8 patients with medically refractory unilateral complex partial seizures using noninvasive in vivo proton magnetic resonance spectroscopic imaging (1H-MRSI) with 4-ml effective voxel size. The brain proton metabolite signals in 8 matched normal controls were bilaterally symmetrical within +/- 10%. The hippocampal seizure foci had 21 +/- 5% less N-acetyl aspartate signal than the contralateral hippocampal formations (p < 0.01). The focal N-acetyl aspartate reductions were consistent with pathology findings of mesial temporal sclerosis with selective neuron loss and gliosis in the surgically resected epileptogenic foci. Proton MRSI correctly localized the seizure focus in all 8 cases. By comparison, MR imaging correctly localized 7 of 8 cases and single photon emission computed tomography correctly localized 2 of 5 cases. No lactate was detected in these interictal studies. No significant changes in choline or creatine were observed. In conclusion, 1H-MRSI is a useful tool for the noninvasive clinical assessment of intractable focal epilepsy. These preliminary results suggest that 1H-MRSI can accurately localize temporal lobe epileptogenic foci.     

Clonidine and methohexital-induced epileptic magnetoencephalographic discharges in patients with focal epilepsies

PURPOSE: During presurgical evaluation, 14 patients with medically intractable focal epilepsies underwent magnetoencephalographic (MEG) recordings for focus localization. To increase the number of epileptic discharges required for MEG analysis, we administered methohexital (MHT), a short-acting barbiturate known to provoke epileptic activity. We also investigated the spike-provoking properties of clonidine in comparison with MHT. METHODS: Patients were briefly anesthetized with intravenously administered MHT after being premedicated orally with clonidine. Numbers and locations of epileptic MEG discharges were assessed after clonidine premedication as well as during MHT anesthesia. Results were compared with baseline MEG recordings. RESULTS: MHT increased the frequency of focal epileptic discharges in 8 of 13 patients ( of the 14 patients did not receive MHT after premedication with clonidine). Premedication with clonidine also increased focal epileptic discharges in 9 of 14 patients. The numbers of epileptic signals and numbers of spikes contributing to MEG source localizations were significantly increased in MEG recordings under both treatment conditions (clonidine premedication and MHT anesthesia) as compared with baseline MEG recordings. CONCLUSIONS: Our results confirmed the selective proconvulsive effects of MHT on the epileptic focus, as previously suggested by EEG and electrocorticographic (ECoG) investigations. However, our present data establish for the first time that clonidine increases epileptic activity in patients with seizure disorders and indicate that clonidine is suitable as an activating agent for localization of epileptogenic foci by MEG. This effect of clonidine on specific epileptic activity also indicates that specific care must be taken when clonidine is used as an antihypertensive drug in patients with seizure disorders.     

Association of circulating endothelium and noradrenaline with increased calcium-channel binding sites in the placental bed in pre-eclampsia

PURPOSE: During presurgical evaluation, 14 patients with medically intractable focal epilepsies underwent magnetoencephalographic (MEG) recordings to localize the epileptogenic focus. To increase the number of epileptiform discharges required for MEG analysis, methohexital a short-acting barbiturate that is known to activate epileptiform activity, was used. Additionally, we investigated the spike-provoking properties of clonidine in comparison to methohexital. METHODS: After oral premedication with clonidine, short-lasting anesthesia was provided by intravenously administered methohexital. The number and location of epileptiform MEG discharges were assessed after clonidine premedication and during methohexital anesthesia. Results were compared with baseline MEG recordings. RESULTS: Methohexital increased the frequency of focal epileptiform discharges in eight of 13 patients (one of the 14 patients did not receive methohexital after premedication with clonidine). Additionally, premedication with clonidine was found to increase focal epileptiform discharges in nine of 14 patients. When compared with baseline MEG recordings, recordings after treatment with both clonidine premedication and methohexital anesthesia showed a significant increase in the total number of epileptiform signals and the number of spikes contributing to MEG source localizations. CONCLUSIONS: This study confirms the selective proconvulsant effects of methohexital on the epileptogenic focus as suggested previously by EEG and electrocorticogram (ECoG) investigations. Additionally, our data establish for the first time that clonidine increases epileptiform activity in patients with seizure disorders. These results indicate that clonidine is suited as an activating agent for the localization of epileptogenic foci by means of MEG. This effect of clonidine on specific epileptic activity also indicates that clonidine should be used with caution as an antihypertensive drug in patients with seizure disorders.     

Correlations between abnormalities on brain SPECT scan and interictal EEG-foci in children with 'intractable' partial epilepsy

SPECT scanning with Tc99mHM-PAO was performed on 40 children with 'intractable' partial epilepsy; 27 patients had abnormalities on SPECT images consisting of areas of decreased cerebral blood flow. In 18 of these 27 subjects there was a good correlation between site of the abnormalities on SPECT scan and interictal EEG foci. 12 patients with regionally decreased CBF had also neuroimaging (C.T. and/or R.M.I.) abnormalities. The brain SPECT provides more precise detection of epileptogenic foci, when used to complement EEG, also in childhood-onset epilepsy.     

A genetic propensity to high factor VII is not associated with the risk of myocardial infarction in men

Interictal brain SPECT is useful for the localization of a seizure focus. Concomitant hypoperfusion of the ipsilateral thalamus on interictal SPECT has been noted for temporal lobe epilepsy. In this study, we aimed to evaluate the prevalence of thalamic hypoperfusion ipsilateral to temporal hypoperfusion (ipsilateral thalamic hypoperfusion) and to assess the usefulness of this finding for the lateralization of epileptic foci on interictal SPECT for temporal lobe epilepsy patients. METHODS: Forty-six patients with refractory temporal lobe epilepsy underwent interictal brain SPECT after intravenous injection of 555-740 MBq of 99mTc-ECD. Perfusion impairments in the brain, especially the temporal lobe and thalamus, were evaluated. The localization of seizure foci was determined in conjunction with scalp, ictal and cortical electroencephalography, MRI and clinical outcomes. Ictal SPECT was performed for 5 of the 12 patients. RESULTS: Concomitant decreased perfusion in both the temporal lobe and the ipsilateral thalamus was observed for 12 (26%) of 46 temporal lobe epilepsy patients on interictal brain SPECT. Seven patients showed hypoperfusion in the left temporal lobe and ipsilateral thalamus. Five patients showed hypoperfusion in the right temporal lobe and ipsilateral thalamus. In addition, hypoperfusion in the ipsilateral basal ganglia (ten patients) or contralateral cerebellum (four patients) was observed. CONCLUSION: Ipsilateral thalamic hypoperfusion is not uncommon in temporal lobe epilepsy. The exact mechanism causing ipsilateral thalamic hypoperfusion is uncertain; however, corticothalamic diaschisis may be an important factor. This finding may aid in the lateralization of seizure foci on interictal brain SPECT.     

Hypothalamic-pituitary-adrenocortical axis function in premenopausal women with rheumatoid arthritis not treated with glucocorticoids

OBJECT: The goal of this study was to determine whether regional cerebral blood flow (rCBF) changes that were found contralaterally to a verified unilateral epileptic focus were associated with the spatiotemporal organization of epileptic abnormalities. METHODS: The CBF in both hippocampi was assessed using stable Xe-enhanced computerized tomography in a series of 19 patients with unilateral mesiotemporal epilepsy. Results were compared according to the distribution of interictal spiking and the spatiotemporal organization of the ictal discharges as determined by stereoelectroencephalography. Two groups were defined: in Group 1 (nine patients), the discharge remained unilateral; in Group 2 (10 patients), the discharge spread to contralateral mesiotemporal structures. For Group 1, the rates of ipsi- and contralateral hippocampal blood flow (HBF) were 32.88+/-15.53 and 45.88+/-17.19 ml/100 g/minute, respectively, whereas in Group 2 they were 36.7+/-11.54 and 36.4+/-11.27 ml/100 g/minute (mean+/-standard deviation). A two-way analysis of variance combining type of seizure (Group 1 compared with Group 2) and HBF (ipsi- compared with contralateral absolute values) demonstrated a main effect for HBF (F[1,17] = 5.051; p = 0.0382), a significant interaction between the two factors (F[1,17] = 6.188; p = 0.0235), and no main effect for type of seizure (F[1,17] = 0.258; p = 0.6178). CONCLUSIONS: In unilateral mesiotemporal epilepsy, asymmetrical interictal hippocampal perfusion was correlated with restricted unilateral ictal discharges, whereas bilateral hippocampal hypoperfusion was correlated with ictal discharges spreading to the contralateral mesiotemporal structures. The lack of correlation between the degree of hypoperfusion and the percentage of neuron cell loss indicated that the decrease in rCBF has both functional and lesional origins.     

Preoperative EEG in medically intractable epilepsy

The aim of the preoperative neurophysiological investigations is to identify the primary epileptogenic focus and its relation to functional cortical areas. The investigations include interictal and ictal extracranial (scalp) electroencephalography (EEG) and invasive methods (depth, subdural, foramen ovale electrodes and peroperative electrocorticography). If an epileptic focus is located in the anterior part of the temporal lobe by the use of scalp EEG, this is normally regarded as sufficient for an anterior lobectomy. However, because of poor spatial resolution by scalp EEG, it is difficult to separate mesial from lateral foci, identify the exact extent of posterior temporal or extra-temporal foci, identify the primary focus in patients with bilateral abnormalities and identify cases with minor scalp EEG-changes. As invasive EEG shows higher spatial resolution and gives an opportunity to evaluate functional areas, invasive EEG has significant advantages in these patients. Use of invasive EEG bears a slightly increased risk and discomfort to the patient, but is necessary in the presurgical evaluation of some patients suffering from medically intractable epilepsy.     

Single-chain Fv with manifold N-glycans as bifunctional scaffolds for immunomolecules

PURPOSE: To investigate the significance of cortical pathology of tonic spasms in patients with tuberous sclerosis. METHODS: The subjects were 38 patients with epilepsy associated with tuberous sclerosis. We analyzed ictal EEGs of tonic spasms and partial seizures by means of video-EEG monitoring for a total of 763 tonic spasms in 20 patients and 107 partial seizures in 15 patients. We also investigated the relation between partial seizures and magnetic resonance imaging (MRI) findings of these patients. RESULTS: Ictal EEG patterns of tonic spasms were divided into generalized and focal patterns. Thirteen patients had only generalized patterns, whereas seven had both patterns. In five patients who had focal ictal patterns of tonic spasms and partial seizures, the location of focal patterns corresponded with the location of onset of partial seizures. Focal discharges were seen immediately before, after, and in the middle of tonic spasms in series in 13 patients. The location of focal discharges also corresponded with the location of the onset of partial seizures in 10 of the 13 patients. Regarding partial seizures, four patients had multiple active epileptogenic foci during the same period, and two others had shifting epileptogenic foci with increasing age. CONCLUSIONS: These findings indicate that cortical pathology plays an important role in the occurrence not only of partial seizures but also of tonic spasms in patients with tuberous sclerosis.     

Bilateral hippocampal interictal spiking and kindling expression in rabbits

The temporal/spatial dissemination of interictal spikes among different brain structures was studied during the course of kindling to determine if the long-term dissemination pattern reflects the rate and expression of kindling. The experiments were conducted on adult rabbits with chronically implanted electrodes (dorsal hippocampus, amygdala, caudate, all bilateral, sensory motor and occipital cortices). Rabbits (n = 13) were subjected to once daily electrical stimulation in the left hippocampus. Kindling resulted in the development of two different epileptic phenomena: 7 animals quickly (in 2-3 weeks) achieved a fully kindled state, characterized by generalized seizures, whereas the remaining 6 rabbits did not reliably progress beyond partial seizures even after more prolonged stimulation. Animals were accordingly divided into two groups referred to as generalized seizure and partial seizure. The temporal/spatial dissemination pattern, particularly in the two hippocampi, was very different between the groups. In both groups interictal spiking originated in one of the hippocampi independent of site stimulated and represented formation of the primary hippocampal epileptic focus. The generalized seizure group demonstrated stability of the primary hippocampal epileptic focus with permanent predominance of spiking in it over the course of kindling, and a high level of bilateral synchronous hippocampal interictal spiking. In the partial seizure group the primary hippocampal epileptic focus was established during the first 2-3 weeks of stimulation. This was later suppressed upon the development of an independent secondary focus in the opposite hippocampus. These animals also displayed very low levels of synchronous bilateral hippocampal interictal spiking. We suggest that an antagonistic relationship can develop between mirror hippocampal epileptic foci. This can be associated with a low level of bilateral hippocampal synchronous spiking, kindling retardation, and manifestation of partial seizures.     

Imaging epileptogenic tubers in children with tuberous sclerosis complex using alpha-[11C]methyl-L-tryptophan positron emission tomography

Several reports have indicated that cortical resection is effective in alleviating intractable epilepsy in children with tuberous sclerosis complex (TSC). Because of the multitude of cortical lesions, however, identifying the epileptogenic tuber(s) is difficult and often requires invasive intracranial electroencephalographic (EEG) monitoring. As increased concentrations of serotonin and serotonin-immunoreactive processes have been reported in resected human epileptic cortex, we used alpha-[11C]methyl-L-tryptophan ([11C]AMT) positron emission tomography (PET) to test the hypothesis that serotonin synthesis is increased interictally in epileptogenic tubers in patients with TSC. Nine children with TSC and epilepsy, aged 1 to 9 years (mean, 4 years 1 month), were studied. All children underwent scalp video-EEG monitoring, PET scans of glucose metabolism and serotonin synthesis, and EEG monitoring during both PET studies. [11C]AMT scans were coregistered with magnetic resonance imaging and with glucose metabolism scans. Whereas glucose metabolism PET showed multifocal cortical hypometabolism corresponding to the locations of tubers in all 9 children, [11C]AMT uptake was increased in one tuber (n=3), two tubers (n=3), three tubers (n=1), and four tubers (n=1) in 8 of the 9 children. All other tubers showed decreased [11C]AMT uptake. Ictal EEG data available in 8 children showed seizure onset corresponding to foci of increased [11C]AMT uptake in 4 children (including 2 with intracranial EEG recordings). In 2 children, ictal EEG was nonlocalizing, and in 1 child there was discordance between the region of increased [11C]AMT uptake and the region of ictal onset on EEG. The only child whose [11C]AMT scan showed no regions of increased uptake had a left frontal seizure focus on EEG; however, at the time of his [11C]AMT PET scan, his seizures had come under control. [11C]AMT PET may be a powerful tool in differentiating between epileptogenic and nonepileptogenic tubers in patients with TSC.     

Rhodamine 123 efflux modulation in the presence of low or high serum from CD56+ hematopoietic cells or CD34+ leukemic blasts by B9309-068, a newly designed pyridine derivative

BACKGROUND: Although magnetoencephalography (MEG) provides accurate information on the spatial distribution and temporal patterns of the "interictal" epileptic activities, it is interictal in nature and therefore also prone to all the problems associated with interictal data. METHODS: We investigated the subclinical "ictal" epileptic activity with a 37-channel, large-array biomagnetometer and mapped the data onto a three-dimensional image in a patient with intractable frontal lobe epilepsy. Dipole source localization was calculated based on magnetic fields for both the interictal and subclinical ictal activities. RESULTS: The current dipoles of the interictal MEG spikes (MEG irritative zone) were revealed to be scattered in the left anterior frontal lobe, whereas that of the subclinical ictal onset (MEG subclinical ictal onset zone) was surrounded by the interictal dipole cluster. The dipole source localization of the propagating activities was not calculated with a single dipole model. The MEG subclinical ictal onset zone correlated well with the ictal onset zone subsequently recorded by invasive subdural electrophysiological monitoring. After multiple subpial transection of the deduced epileptogenic area, a dramatic reduction of the seizures occurred. CONCLUSION: These results illustrate the potential of MEG for localizing the epileptogenic foci with high spatial and temporal resolution.     

Case report: fibrolamellar hepatocellular carcinoma in a Japanese woman: a case report and review of Japanese cases

There have been few reports on cerebral arteriovenous malformation (AVM) of newborns. We present here an interesting case of occult AVM diagnosed 17 years after an episode of acute subdural hematoma in the neonatal period. The cause of subdural hematoma had remained unclear and the patient had suffered from an intractable epilepsy of 17 years duration. Seizures were mainly characterized by drop attacks and included other seizure types such as complex partial seizure and generalized tonic clonic seizure. The symptoms had gradually become worse and the intervals between the occurrences of symptoms had become shorter. An interictal scalp EEG showed a focal spike in the left temporoparietal lobe. CT and MRI of that region demonstrated a porencephalic cyst which was supposed to have resulted from an old hematoma. There were no vascular abnormalities in angiography. Temporoparietal craniotomy and a corticogram were performed. The cortex with a focus was resected and the disappearance of a focal spike in the corticogram was confirmed during operation. Microscopically the cortex included AVM with gliosis. The initial postoperative course was good and seizures disappeared immediately after the operation. However, the symptoms of drop attacks observed before operation began to occur again 3 months later. The fact of postoperative recurrence suggests that the long history of the patient's seizures originating from AVM may have produced secondary epileptic foci.     

Malignant lesions presenting as symptoms of craniomandibular dysfunction

We compared the findings of scalp electroencephalogram with subdural electrode array (SEA) recordings in 19 patients with refractory frontal lobe epilepsy. Prolonged scalp interictal recordings localized the epileptogenic zone in 12 patients; seven had no interictal sharp waves. The SEAs showed multifocal interictal sharp waves in all patients. Seven patients with localized seizure onset on scalp recording showed extensive ictal onset on the SEA recording. Five patients with lateralized seizure onset to one hemisphere on scalp recording were found to have ictal onset on SEA restricted to a smaller area. Because of the large epileptogenic zone found on SEA recordings, a complete resection was possible in only five (33%) of the 15 patients who had resections. Eight (53%) of the 15 patients benefited from surgery (mean follow-up, 4.6 years). The SEAs also allowed functional localization in most patients. From these data, we suggest that a localizing scalp electroencephalogram in patients with frontal lobe epilepsy may be misleading because SEA recordings show larger epileptogenic zones than anticipated. Furthermore, we postulate that the larger extensive epileptogenic zone may account for the poorer surgical outcome in patients with frontal lobe epilepsy compared with patients with temporal lobe epilepsy.     

Cerebral blood flow in hypertensive patients: an initial report of reduced and compensatory blood flow responses during performance of two cognitive tasks

We asked whether the altered cerebral vasculature associated with essential hypertension might dampen or redirect the regional cerebral blood flow (rCBF) response to cognitive work. Relative rCBF was assessed with [(15)O]water positron emission tomography during a working memory task, a memory span task, and two perceptual control tasks. Unmedicated hypertensive patients and control subjects differed in rCBF response during both memory tasks. Hypertensives showed relatively diminished rCBF responses in right hemisphere areas combined with compensatory activation of homologous areas in the left cerebral cortex. Essential hypertension appears to selectively influence the circulatory reserve of portions of cerebral cortex and secondarily induce recruitment of other cortical areas to process certain tasks.     

Nonlinear dynamics of epileptic seizures on basis of intracranial EEG recordings

PURPOSE: An understanding of the principles governing the behavior of complex neuronal networks, in particular their capability of generating epileptic seizures implies the characterization of the conditions under which a transition from the interictal to the ictal state takes place. Signal analysis methods derived from the theory of nonlinear dynamics provide new tools to characterize the behavior of such networks, and are particularly relevant for the analysis of epileptiform activity. METHODS: We calculated the correlation dimension, tested for irreversibility, and made recurrence plots of EEG signals recorded intracranially both during interictal and ictal states in temporal lobe epilepsy patients who were surgical candidates. RESULTS: Epileptic seizure activity often, but not always, emerges as a low-dimensional oscillation. In general, the seizure behaves as a nonstationary phenomenon during which both phases of low and high complexity may occur. Nevertheless a low dimension may be found mainly in the zone of ictal onset and nearby structures. Both the zone of ictal onset and the pattern of propagation of seizure activity in the brain could be identified using this type of analysis. Furthermore, the results obtained were in close agreement with visual inspection of the EEG records. CONCLUSIONS: Application of these mathematical tools provides novel insights into the spatio-temporal dynamics of "epileptic brain states". In this way it may be of practical use in the localization of an epileptogenic region in the brain, and thus be of assistance in the presurgical evaluation of patients with localization-related epilepsy.     

Clinical examination on localization-related epilepsies with elementary visual seizures--clinical, electroencephalographic and imaging diagnostic studies

The clinical, electroencephalographic and Imaging diagnostic features of the 45 patients of Localization-related Epilepsy who had elementary visual symptoms at seizure onset were investigated. There were 24 males and 21 females aged 19 to 78. Their ages at seizure onset ranged from 1 to 55 with a mean of 15.4. The patients were divided into 3 groups based on the pattern of elementary visual symptoms: Group 1; 23 patients (51%) with only elementary positive visual symptoms, Group 2; 9 patients (20%) with only elementary negative visual symptoms, Group 3; 13 patients (29%) with others. It came to our notice that 8 (18%) patients in Group 3 had positive + negative (P*N) visual seizures such as scintillation scotoma. It was quite difficult to draw a distinction between the P*N seizures and scintillation scotoma in migrainous patients in quality. Therefore, a question arises whether similarities between them are ascribed to the same underlying mechanism. It is possible that the mechanism of the P*N seizures is different from that of the scintillation scotoma, but the both produce the same condition. However, we are not competent to discuss this hypothesis. Further work along this line is necessary. In addition to the elementary visual symptoms, autonomic (69%), focal motor (29%), illusion (29%), vertiginous (22%) manifestations, etc. were also observed. These manifestations suggest that epileptic ictal discharges spread into many different brain areas. Regarding Group 1-3, occurrence of illusional seizures was more common in Group 2. In this group, in only one patient, occipital interictal discharges were observed. The subjects were subclassified into two groups depending on whether the seizures were well controlled (good outcome) or poorly controlled (poor outcome group). On these groups, comparative studies were performed. The poportion of the patients with a family history of convulsive disorder was higher in the latter than that in the former. To the contrary, the poportion of the patients with a etiologic episode was higher in the former than that in the latter. With respect to the imaging study, regardless of localizations, abnormal findings were detected in 25% on CT scan, in 29% on MRI, and in 71% on SPECT. Whether or not these abnormal findings completely or partially agreed with presumed epileptogenic brain region (occipital lobes) was investigated. CT scan was positive (correspondent) in 8%, MRI was positive in 13%, and SPECT was positive in 54%. The incidence of SPECT abnormalities was higher in the poor outcome group (70 %) than that in the good outcome one (43%). We may, therefore, conclude that SPECT seems to be useful for the detection of epileptogenic region, especially in intractable cases. But the incidence of these imaging studies' abnormalities located in occipital lobe was not so high, therefore, there seems to be no doubt that clinical symptoms and EEG findings are most important for diagnosis.     

Comparison of technetium-99m-ECD to Xenon-133 SPECT in normal controls and in patients with mild to moderate regional cerebral blood flow abnormalities

Technetium-99m-1,1-ethyl cysteinate dimer (ECD) has been proposed as a "chemical microsphere" for SPECT measurement of regional cerebral blood flow (rCBF). However, its distribution has not yet been compared in humans to an established rCBF measure. Therefore, we compared the uptake and distribution of ECD with rCBF measured by 133Xe SPECT in subjects with mild to moderate flow abnormalities and in normal volunteers. Blood and urine chemistries and vital signs were unchanged from pre-ECD values up to seven days postinjection. Profile plots demonstrated pattern agreement between rCBF ratios (133Xe) and ECD count density ratios. A significant correlation of rCBF ratios to ECD count density ratios was observed (r = 0.77), with a slope of 0.64 and intercept of 0.36. To explore whether or not the relationship between rCBF and ECD was dependent on absolute flow, ECD region of interest data were expressed in units of ml/min/100 g by equating global CBF (133Xe) and ECD global count density. A closer correlation (r = 0.88) was found for these data than for the count ratio data. The slope was closer to one (m = 0.83) and the intercept was closer to zero (b = 8.2). Also, a significant correlation was observed between ECD-derived rCBF and 133Xe rCBF in the lesion area (r = 0.92) for patients with well-demarcated rCBF lesions. The slope (0.80) suggested a slight underestimation of lesion flow by ECD. Finally, ECD clearance from cortical gray matter ROIs derived from high-resolution scans from 1 to 4 hr postinjection was slow (2.4%/hr). In summary, ECD is a safe and effective marker of regional cerebral perfusion. The distribution of ECD is linearly related to rCBF measured by 133Xe SPECT, although our data suggest a mild underestimation of flow at the high end of the normal range.